Arduino Data-Logger Shield with the FRDM-KL25Z Board

One success factor of the Arduino platform is the broad availability so-called ‘shields': hardware plugin-modules which extend the capability of platform. currently lists 288 different shields available! Clearly, Freescale wants to benefit from that ecosystem with the Freedom FRDM-KL25Z board which features Arduino compatible headers. Time to use the Freedom board with an Arduino shield :-).

Data Logger Shield on Top of Freedom Board

Data Logger Shield on Top of Freedom Board

Data Logger Shield Hardware

I ordered a the Adafruit Data Logger Shield as a kit: to solder such a kit is fun :-), and gives me the freedom what to put on the board. The schematics of the shield can be found here.

The board features an SD card with level shifter (required to work with 3.3V and 5V devices), two LED’s, a reset button, an I2C battery buffered realtime clock plus a prototype area. The minimal SD card pins (MISO, MOSI, DeviceSelect, BusCock) and I2C (SDA, SCL) bus are connected to the shield connector rows, while the two LEDs and the card write protect and card detect pins can be routed to any pins with a wire or any other kind of connection.

Data Logger Top View

Data Logger Top View

In above picture the green wire is for WP (SD card Write Protection pin), the white wire is for the CD (SD Card Detect) pin. The yellow wires are for the red and green LED.

Freedom_FatFS Application

The application is Eclipse based CodeWarrior for MCU10.3 application. It uses the SD card with the open source FatFS file system.

:!: The FAT_FileSystem and SD_Card component have been updated to work with Kinetis. So make sure you use the latest component from EmbeddedComponents for this project.

Freedom_FatFS Processor Expert Components

Freedom_FatFS Processor Expert Components

  • GenericTimeDate: needed for date and time information, as the file system needs date/time attributes for files on the file system
  • Wait: generic busy wait routines, needed by the SD card driver because initialization of the SD card driver needs to wait for a time as specified in the SD card standard.
  • Timeout: As SD card operations can take a very long time (several hundreds of milliseconds), this timeout driver allows to wait for a given time.
  • SPIMaster_LDD: implements the SPI bus driver using interrupts.
  • FAT_FileSystem: Implements the FAT file system.
  • SD_Card: Low level SD card driver implementing the memory device.
  • TimerInt_LDD and TimerUnit_LDD: implement a 10 ms timer used for the Timeout component.
  • Init_GPIO: Init components used for pull up resistors for the WP and CD signals (see this tutorial).
  • LED and GPIO_LDD: Driver for the RGB LED on the Freedom board (see this tutorial). Note that the signal for the blue RGB LED is used for the SD card SPI clock signal by the Data Logger Shield.
  • BitIO_LDD: Used for the green and red LED on the shield (see this tutorial).

The project and components can be easily changed for any other SD cards. In any case, here are tips and hints how the project is configured:

KL25Z with 48 MHz

In order to run the SPI bus with up to 12 MHz, the CPU core clock is configured to run at 48 MHz:

48 MHz Core Clock

48 MHz Core Clock

SPIMaster_LDD Configuration

The SPI component needs to be configured for the MISO, MOSI and CLK pins, *without* :!: Chip select and two :!: clock configurations, each with ‘MSB first’, ‘Low Clock polarity’ and ‘capture on leading edge':

SPI Configuration

SPI Configuration

The Attribute Set 0 needs to point to Clock rate index 0, and the so the Attribute Set 1 to Clock rate index 1. The reason is that we need to SPI clock speeds: a maximum of 400 kHz for card initialization and up to 20 MHz for normal operation. What we can achieve here is 375 kHz and 12 MHz.

The two speed modes need to be set in the clock rate settings:

Clock Rate Settings

Clock Rate Settings

In the Timing Dialog the two SPI clock speeds need to be configured with ‘list of values':

Timing Dialog

Timing Dialog

The two speed modes are referenced from the SD_Card component properties:

Slow and Fast Speed Modes

Slow and Fast Speed Modes

Timeout Component

As the SD card requires up to several hundreds of milliseconds delay, the Timeout component is used.

SD_Card Timeout Properties

SD_Card Timeout Properties

For this a 10 ms timer is configured with the TimerInt_LDD component. What easily gets missed is to call the AddTick() method in Events.c from the 10 ms timer interrupt:

** ===================================================================
**     Event       :  TI1_OnInterrupt (module Events)
**     Component   :  TI1 [TimerInt_LDD]
**     Description :
**         Called if periodic event occur. Component and OnInterrupt
**         event must be enabled. See  and
**         methods. This event is available only if a <Interrupt
**         service/event> is enabled.
**     Parameters  :
**         NAME            - DESCRIPTION
**       * UserDataPtr     - Pointer to the user or
**                           RTOS specific data. The pointer passed as
**                           the parameter of Init method.
**     Returns     : Nothing
** ===================================================================
void TI1_OnInterrupt(LDD_TUserData *UserDataPtr)

WP and CD Pins

Optionally the SD card holder can provide WP (Write Protect) and CD (Card Detect) signals. They are available in the SD_Card component settings:

CD and WP Pins

CD and WP Pins

If the signals do not have pull-ups or pull-down resistors on the board (as for my shield), they need to be configured in ‘pin-sharing’ mode and with pull-ups enabled (see this tutorial).

The WP signal is connected to the shield D8 line, and the CD signal is connected to D9.


The projects used the RGB LED on the Freedom board plus the two LED’s on the Shield. The two shield LED’s are connected to the shield D7 and D6 lines.

LED Components in Component View

LED Components in Component View

Example Code

The example code is in ProcessorExpert.c:

static FATFS fs;
static FIL fp;

static void Test(void) {
  UINT bw; /* number of bytes written */

  if (FAT1_isDiskPresent()) { /* if no hardware CardDetect pin is assigned, it will always return TRUE */
    LED_Rd_On(); /* turn red RGB LED on */
    FAT1_mount(0, &fs); /* mount file system */
    if (!FAT1_isWriteProtected()) { /* if no hardware WritePtotect pin is assigned, it will always return FALSE */
      LED_Gr_On(); /* turn green RGB LED on */
      if (FAT1_open(&fp, "./test.txt", FA_CREATE_ALWAYS|FA_WRITE)!=FR_OK) { /* open file, will always create it if not already on disk */
        for(;;){} /* error! */
      if (FAT1_write(&fp, "Hello World!", sizeof("Hello World!")-1, &bw)!=FR_OK) { /* write string to file */
        for(;;){} /* error! */
    (void)FAT1_close(&fp); /* close file */
    FAT1_mount(0, NULL); /* unmount file system */

If a card is inserted, the Red RGB LED will be on and the file system will be mounted. If the card has not the write protection tab on, it will write a file ‘test.txt’ with an example text in it.


For now I only have this shield, and it worked very well with the Freedom board. The shield has an I2C Real-Time-Clock on it for which I did not wrote a driver yet. That would give me a battery backed up clock which would make it ideal for a data logger application. Again, still some work to do :-).

I need to check/measure the SD card speed, but for now it is reasonable for my tests. For sure I will need to extend my Shell Project with the SD card capabilities.

The project and sources is available from this link. Code size with gcc and even not optimized at all is less than 18 KByte, so very reasonable.

Happy Shielding :-)

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127 thoughts on “Arduino Data-Logger Shield with the FRDM-KL25Z Board

  1. Pingback: Arduino Data-Logger Shield with the FRDM-KL25Z Board « adafruit industries blog

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  6. Hi there,
    First of all Thanks for this HOWTO. Trying to do it for myself I got stuck waiting for SD1_DataReceivedFlag. The problem is that this flag is set in your SD1.c file at the bottom

    void SM1_OnBlockReceived(LDD_TUserData *UserDataPtr)
    /* Calling inherited event */

    While SM1 is the SPI Object. This Function is in my Events.c and by including it via
    extern bool SD1_DataReceivedFlag;
    it now works. Maybe i overread it but i couldnt find it in the text. This info could be useful for others too.

    Bis dann,

    P.S. you got some nice photographic skillz ;)

    • Hi Julian,
      I did not point out all the details. For this I have posted the full project. You are right, that code in Events.c easily get missed (happend to me several times too), so thanks for pointing to this.

      • Hi Erich,

        I had the same problem. This project when compiled has an empty onBlockReceived event.

        void SM1_OnBlockReceived(LDD_TUserData *UserDataPtr)
        /* Write your code here … */

        Which causes the program to hang waiting for the data received flag.

        Thanks for all the great PE components. You do a great service to Freescale and the embedded community.


      • Hi Jeff,
        good if things are solved on your end, otherwise let me know.
        Yes, the ‘events’ model in Processor Expert is powerful, but a constant source of missing implementing the hook itself, especially if porting one project to another. I’m considering to add to my own created components a dual interface for components with events: a normal ‘Events.c’ kind of interface, plus an interface which allows the calling application to install the hook with a function pointer: uses little more RAM, but avoids mistakes.

  7. Hi Erich,
    I’ve implemented this project for a K70, and my write throughput is extremely low.
    With the SPI clock at 12.5MHz, I’m only seeing ~100KB/s.

    Having a K70, I’m sure you’re wondering why I would use SPI and not use the SDHC…
    Two reasons:
    1 – we’re considering having multiple uSD cards connected via SPI, so writing via SPI is not a wasted lesson.
    2 – I’ve used the SDHC, and still get low throughput! (depending on the card I get ~250-300 KB/s)

    I keep the SDHC clock at ~5MHz, as going faster results in my program erroring out in the FATFs writes.
    My throughput calculations are calculated by timing the writing of an 8MB file to the card. The data is simply a 512 byte buffer that is written repetitively.

    What kind of throughput do you get when using SPI mode ?
    If you have done similar with SDHC, what kind of throughput did you achieve there ?
    Any “gotchas” that I may be overlooking that I can look at ?


    • Hi Chandler,
      Yes, I have been as well disappointed by the read/write performance. My conclusion is that it heavily depends on the buffer size, plus on the SD card used. I have seen SD card differences by several factors. It seems to me that especially larger and newer SD cards are slower. I have found a few 512 MByte (yes, that small!) which have the best read/write performance. Simply because their internal flash block size is smaller.
      On I have a simple benchmark example for the K60 (SDHC) and K70 (SPI).
      My results are (all for a file with 100’000 bytes):
      K60/SDHC (results first with a micrSD card, and a normal SD card):
      – creating file: ~4000 ms / 4600 ms
      – reading file: ~2500 ms / 2500 ms
      – copy file: ~6400 ms / 9200 ms
      here you already see that there can be big differences.
      As for SDHC, I had filed a ticket because using multiple pins had no improvements on my side. I still need to follow the advice, but basically it is about increasing buffer size (I did not verify this).

      I’ll check the numbers on the KL25Z and with a ColdFire V2 and post it up here.

      As a side note: I have improved some of the SPI driver part in the sources on GitHub: basically using more block transfers than writing/reading single bytes. This had a positive performance impact. Not sure if you are using the drives from GitHub, but this might give you a performance boost.

      Best regards,

      • Hi Chandler,
        I have published another example with ColdFire V2 52259 (using SPI), available on
        And I get:
        CMD> run benchmark
        Benchmark: open file, write 10k times 10 bytes (100’000 bytes), close file:
        Deleting any existing files…
        Creating benchmark file…
        1490 mseconds needed for command.
        Reading benchmark file…
        960 mseconds needed for command.
        Benchmark: copy file (100’000 bytes):
        Going to copy file…
        2850 mseconds needed for command.

      • Thanks Erich!
        I have used the examples and drivers on GitHub before.
        I’ll take a look at the updated examples/drivers soon.

        I’m currently working on stripping down the SDHC PE code to remove the software overhead.
        Once I have that working, I will implement multiple block transfers.
        I’ll then test writing raw sequential blocks to the card to see what kind of speeds I can get, as this should be the fastest method possible.
        (Using CrystalDiskMark on the PC to test cards, I’ve seen sequential write speeds as high as 18MB/s…I don’t expect to get anywhere near there, but I would like to break the MB/s rate on the K70!)

    • Hi Erich,
      I was finally able to get some work done with the SDHC and I am very happy with the results.

      I stripped down the PE driver and made it more straight forward and efficient.
      One example was the write, where the PE driver would first do a read before a write. While this makes sense to handle writing sizes smaller than a block, a simple “if write size == block size” could have saved the unnecessary read overhead!

      Since the PE code was already setup using single block transfers, I first tested some writes while varying the SDHC clock speed.
      For 1MB of data and a 50MHz SD clock, the write time was ~8 seconds.
      I then took measurements while slowing the clock down in increments all the way to 1.25MHz, where to my surprise, the 1MB of data only took ~10 seconds.
      I scoped all of the signals and noticed a ~4ms pause between every block, which was apparently not dependent on the SD clock.
      A single 512-byte block with a 50MHz clock was writing in ~25 microseconds…so of the 8 seconds to write 1MB, only about 50ms was data the strobing while the rest of the time was a busy state (presumably as the card actually wrote the data).

      Next I implemented multi block transfers and tested with a 50MHz SD clock.
      I first tested 16 blocks per transfer and was seeing a 1MB transfer time of ~550ms!
      Unfortunately, here is where I got some strange behavior…
      At 50MHz clock, I would sometimes get in an error state I could not recover from.
      At 37.5MHz clock, it worked 100% of the time, AS LONG AS I was debugging, but I often hit the error state when not debugging.
      After testing multiple clock speeds, it appeared that 18.75MHz seemed to work 100% of the time, even when not debugging.
      To get a more realistic data transfer measurement, I measured transfers of 128MB.
      At 18.75MHz SD clock with 16 block transfers, the write time was 80 seconds, giving a write speed of 1.6MB/s.

      The last test was to increase the number of blocks per write. I tested 32, 64, and 128.
      With 128 block transfers, the full 128MB of data took only 21 seconds for a transfer speed of ~6MB/s !
      I’m unable to increase the blocks per write further without running out of on-chip memory. (I still need to get external DDR functioning correctly…)
      However, unless I can figure out why the higher clock speeds result in errors, I’m essentially at the data write limit anyway.

      I am very pleased with the write time of 21 seconds for 128MB of sequential data.
      Although this is purely write time, the rate is MUCH higher than what I saw trying to use PE (more than 50x faster!).

      • Hi Chandler,
        that’s really good news. I wonder how I could apply this to the SPI based driver too. Are you saying you did the changes on the low level PEx code? Or at the interface layer of FatFs? Would you be so kind to share your details so I could incorporate this to the files on the MCUonEclipse GitHub page so everyone could benefit?
        Many thanks,

      • Hi Erich,

        This is all low level SDHC code with no FatFS involvement. Although our project will use a FAT32 file system, the key for us is storing large chunks of sequential data quickly. With the emphasis on “quickly” and the files being sequential, I wouldn’t want the overhead of FatFS. Our project will handle the FAT table with some simple streamlined code as we know how data will be laid out, etc.

        As a side note, I was able to test increased number of blocks per write, testing 256, 512, 1k, 2k, and 4k blocks per command. At 512 and above, the 128MB write time was ~16.5s. Considering the time to strobe 128MB at my SD clock speed is a little over 14 seconds, ~2.5 additional seconds for other commands and busy delays sounds about right. The only way I could get faster would be being able to increase the SD clock speed without errors.

        The code I have now has no error checking and is just basic code in the main function. I used the source code from the PE driver as a guide. I am still using the SDHC_Init component to initially setup the SDHC.
        *** HOWEVER, note that this basic init function is INCOMPLETE! Part of the initialization process should involve setting internal pullups on the the data lines. (This was a gotcha that took me some time to find unexplained errors. The weird thing is that the init function in the SDHC LDD component does the pin setup correctly…)

        The basic flow of the program is as follows:
        // note that all sent commands below poll command complete flag in the IRQSTAT register before continuing to next step
        // additionally, transfer commands will poll transfer complete flag after the command complete flag is set
        // some of the bit masks for arguments and checks I have as DEFINES, but I don’t have the header in front of me right now…you should be able to find them in the SDHC_LDD generated code

        – detect card is inserted via card detect pin

        // reset all cards
        set CMDARG to 0
        send CMD0 (no response type)

        // test high voltage and check pattern
        set CMDARG to 0x1AA
        send CMD8 (response type 48)
        test CMDRSP0 for 0x1AA; proceed further if response matches

        // wait for power up
        set powered flag to false
        while !powered {
        set CMDARG to 0
        send CMD55 (response type 48)
        send ACMD41 (response type 48)
        test CMDRSP0 for CARD_POWER_STATUS;
        if bit is high, set powered to true to break from loop

        // begin card registration
        set CMDARG to 0
        send CMD2 (response type 136)

        // RCA request
        set CMDARG to 0
        send CMD3 (response type 48)
        store RCA from CMDRSP0

        // select card
        set CMDARG to RCA
        send CMD7 (response type 48 busy)
        test CMDRSP0 for READY_FOR_DATA

        // deselect card
        set CMDARG to 0
        send CMD7 (response type 48)
        clear timeout error in IRQSTAT (this is an expected timeout)

        // get CSD
        set CMDARG to RCA
        send CMD9 (response type 136)

        // select card
        set CMDARG to RCA
        send CMD7 (response type 48 busy)
        test CMDRSP0 for READY_FOR_DATA

        // get SCR
        set BLKATTR to block count 1 and SCR block length
        setup ADMA descriptor for SCR transfer
        set CMDARG to RCA
        send CMD55 (response type 48)
        set CMDARG to 0
        set ADSADDR to descriptor address
        send ACMD51 (DPSEL | response type 48 | DTDSEL | DMAEN)
        *** after command complete and transfer complete, response is stored in buffer pointed to by descriptor

        // get SFS
        set BLKATTR to block count 1 and SFS block length
        setup ADMA descriptor for SFS transfer
        set CMDARG to high_speed
        set ADSADDR to descriptor address
        send CMD6 (DPSEL | response type 48 | DTDSEL | DMAEN)
        *** after command complete and transfer complete, response is stored in buffer pointed to by descriptor

        // set bus width to 4 bit
        set CMDARG to RCA
        send CMD55 (response type 48)
        set CMDARG to WIDTH_4_BIT
        send ACMD 6 (response type 48
        set SDHC_PROCTL to use 4 bit data

        // clock speed change
        IF setting SD clock to >= 25MHz
        send CMD6 (response type 48 busy)
        END IF
        disable clock in SDHC_SYSCTL
        set new clock frequency
        poll SDHC_PRSSTAT for stable clock
        reenable clock in SDHC_SYSCTL

        // setup data to store

        additionally, setup ADMA descriptors pointing to data to store
        all descriptors will be set for transfer and valid
        additionally, the last one has the END bit set

        // send block length
        set CMDARG to block length
        send CMD16 (response type 48)

        // set block count ??? not sure this is necessary, since SDHC handles auto command 12
        set CMDARG to block count
        send CMD23 (response type 48)

        // transmit data loop
        for loop here to continuously send data
        *** the first 2 commands send the pre erase function
        *** this is mentioned in the spec to potentially make some cards write faster
        *** I didn’t notice any improvements, so it may be wasted time…
        set CMDARG to RCA
        send CMD55 (response type 48)
        set CMDARG to multiple block num
        send ACMD23 (response type 48)
        set CMDARG to sector to write
        set BLKATTR to multiple block num
        set ADSADDR to first descriptor address
        send CMD25 (DPSEL | response type 48 | MSBSEL | AC12EN | BCEN | DMAEN)
        wait for command complete and transfer complete
        set CMDARG to RCA
        send CMD13 (response type 48)
        *** test CMDRSP0 in while condition ***

        end of for loop

        That is what works for me. Obviously, I still have to implement some error checking, but this operated well enough with 120MHz processor clock and 20MHz SD clock. Higher than 20MHz results in errors in the data writes, and I haven’t quite figured out what the problem is. On the PC, the same card operates fine with a 50MHz clock (tested via bus analyzer) and sees sequential write speeds up to 17MB/s. The original PE code would choke for me when I got the clock above 5MHz and had extremely slow write speeds, so I’m still pleased at this point with what I have ;)

        Let me know if you have any questions.


      • One last little note…
        In the process of doing some error handling for my code, I discovered the “magic register bits” that allowed me to run the SD clock at the full 50MHz with no errors.
        This allowed me to get write speeds of ~16MB/s with 128MB of sequential data in ~8 seconds.
        This nearly matches the 17MB/s seen on my PC benchmarking for the same card. My timing resolution is 1 second, so it could be closer than I think.

        The bits to change were the DTOV bits.
        Setting them to SDCLK * 2^27 allowed me to run at maximum speed with no errors.

      • Wow, that’s really interesting.I’m right now absorbed with non-SD-card work, but that’s definitely something I need to try out afterwards :-) Thanks for sharing!

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  9. I’ve been playing with this code on the FRDM-KL25Z with the hope of getting something to play from an SD card to the DAC. My chosen format is mono, uncompressed 22.05kHz sampling rate, 16-bit audio which I think has a reasonable chance of being doable with SPI SD card reads and the DAC.

    I basically took this project and added a TimerInt (which drives the DAC sample output), a DAC and a couple of IO pins which are specific to my setup. Despite having the interrupt driven DAC code and this example working fine, I have problems when tying the two together.

    I have a double-buffered setup. I start by filling both buffers from the SD – which works fine. I then enable the audio interrupt which outputs the next sample each time it is called. When it gets to the end of a buffer it swaps the front and back buffers, resets the sample indexer and fills the back buffer from the SD.

    However, the third SD read call (the first driven by the audio interrupt) sits waiting forever for SD1_DataReceivedFlag (before you say so, I have of course already got this correctly implemented in events.c otherwise the first read would stall it, not the third). I’ve tried a few things including different buffer sizes (just guessing) and then popped my scope on the SPI pins.

    Oddly, the SPI pins work fine for the first two calls (as we should expect, since we get correct returns) and yet they do NOTHING in the third call at all. It’s almost as if SPI is disabled inside the TimerInterrupt…

    If anyone could shed some light on this I would be most appreciative. Happy to send you what I have so far. Also, if anyone knows anyone who does a little freelance consulting who could help me out that would be something I would consider.


      • Hey again Erich.

        I’ve not even begun to explore the RTOS side of things. The example I have based this on is the one directly linked from this page, not the RTOS-based one on GitHub. I actually couldn’t get that one to build as the shell component was not being recognised by CodeWarrior. I will take a look in the reference manual – I wonder if I am mixing the two TimerInterrupts badly – perhaps this somehow disables SPI0. Need to get reading I think!!

        Thanks for taking a look though – I will read the RTOS article anyway :)

      • Hi Stefan,
        for the projects on GitHub, you will need the Processor Expert comonents on GitHub too.
        Yes, you can use the ‘original’ projecs and components, but as you might see from the commit messages on GitHub, things have been progressed a lot :-).

      • Hey Erich

        I have been using some of the examples from GitHub with components from This normally works but for the FATFS example the shell component doesn’t appear supported. I haven’t yet worked out how to compile the GitHub components into something I can actually import into CodeWarrior. I think there is info somewhere on mcuoneclipse about this – this project is only getting an hour or so at a time right now!

        I have a few ideas on ways forward starting with reading the processor reference manual!

      • Hi Stefan,
        the wiki page on GitHub ( explains how you can import the GitHub components into your CodeWarrior IDE. The components on have been exported as *.PEupd files. That’s still possible with the CDE component in CodeWarrior for MCU10. But as exporting these components is a lot of additinal efforts, and there is no way to automate this export process, I decided to put the component sources on GitHub: that way everyone can get the components too, and even stay in sync easily, or fork the repository. Let me know if the GitHub way does not work out for you. In that case I could make an exception :-) and export the FatFS plus Shell for you.

      • Hey Erich

        Thanks for all the help. Getting beans into the system is easy once you know how! I’m all up to date now. I ended up sticking with the non-FreeRTOS version as I really don’t know my way around RTOS of any sort and it was all starting to go over my head.

        However, your original point regarding interrupts was very helpful – turned out I was calling the SD card read routine from within my timer interrupt. Changing this to setting an asynchronous flag and dealing with it in the main loop sorted everything out :)

        Still lots to do however!!!

      • SD_CS is the SPI chip select signal, or SD_SS (Slave Select). Are you using the same Arduino SD data logger shield? Then this would be on PTD0.

      • 1.- Oh I see, According to the diagram of the logger shield, one can observe the pin signal SD_CS connected to D10 (PTD0) . But where I should be this connection inside the codewarrior? I didn’t understand when you said:

        “SPIMaster_LDD Configuration

        The SPI component needs to be configured for…, *without* Chip select …”

        2.- About the second doubt, RTC1 doesn’t appears. I have all the component installed. Even after of installing them from GitHub.

      • About the SPI chip select: if you configure the SPIMaster_LDD having the chip select, then the usage of the chip select is under the control of the SPI component: means the application cannot control it. The chip select is automatically asserted whenever it sends an SPI data packet. However, to work with the SD card especially during initialization, the CS pin needs to be toggled and asserted without sending data over the SPI bus. So the usage of the chip select shall not be bound to the SPI data transfer. Instead of having the chip select controlled by the SPI component, it is controlled by the SD_Card component, where you have a ‘Slave Select’ setting for it.

      • That SD card adapter is fine, and looks it has the 3.3V level shifter.
        As for the RTC component: I’m not sure why you do not see it in the Components Library view. I have sent you an email with the component package. Let me know how it goes.

      • Hi Erich

        My report:

        I don’t know what was happening. Perhaps I had an old version of the downloaded project. I downloaded the file again from the link of this tutorial and the RTC is now visible.

        I started from scratch and I didn’t see again the issue about “SD1_DataReceivedFlag=TRUE” in the first comment of this section of “What do you think?”. All code was in place. But I admit that I see that detail before too.

        Now only a question: how I write a new line for each time that “Test function” is being executed? I mean, I want see my TEST.txt with:
        “Hello World”
        “Hello World”
        “Hello World”


      • Hi Lucia,
        in a nutshell: open the file, write to it, then close it.
        You might have a look at the example provided in the FatFS component (FAT1_Benchmark) how to write to a file.

      • I forgot to say that:

        I updated the “Component Library” with all the components. I used the link you provided. Thanks!

        The GPIO1:GPIO_LDD didn’t appear. I realized that the project was using the new(updated) LED’s component.

      • Yes. I undestand that, but how I put the format “\r\n”? I tried it by enabling the StringFunctions of the FAT1_FileSystem but it doesn’t work, I get errors and I realized that the string functions appear as comments in the FAT1.c.


      • Hi Lucio,
        I admit that I have not used the string functions, as I have not needed them. I need to check the code if I can fix this. As for writing “\r\n”: simply put it into your buffer and write it to the file.

      • I have reached to obtain: “HelloWorldHelloWorldHelloWorld…”, and if I write: “FAT1_write(&fp, “Hello World!/n”, sizeof(“Hello World!/n”)-1, &bw)” I see this: “HelloWorld/nHelloWorld/nHelloWorld/n…”

      • Because I was distracted…I did not notice of the wrong character.
        Anyway, It doesn’t run with only “\n”, but with “\r\n”. Thanks for your help and your time!

      • Well, both \n and \r\n are correct. It is just that Linux typically only uses \n, while Windows is using \r\n. But many editors (like Eclipse) are handling this automatically.

  10. Hi Erych,

    Thanks for the great series of writeups! I’m not sure I could have gotten this far with Freescale/CodeWarrior development if not for them.

    Do you have any idea why, when I switch to SPI1, I can’t get the project to work? All I’m doing is taking a working version with SPI0 and changing the SPI pins and InitGPIO to reflect a change to SPI1. I see that they are clocked differently but I don’t see why that would matter unless I’m missing some extra configuration.


    • Hi Vishal,
      thanks for reading and for your feedback!
      As for SPI1: you might need to check it with a logic analyzer, if you get the proper signals. You mention the clocking: this is important for SD-Cards at least in the startup phase of talking with an SD card: you need to keep the clock below 400 kHz until the SD-Card is initialized.
      I hope this helps.

      • Thanks, Erich. (Sorry for the misspelling :( I guess I stole the ‘y’ from your last name.)

        I did see that Processor Expert was automatically honoring the clock speeds I set for SPI0 in the Clock Path tab (which was slightly different for SPI1). I don’t know the SD/SPI stuff well enough to debug the communication with a logic analyzer, but that’s a good point. I can at least compare the faulty SPI1 communication to SPI0 and see what’s going on with clocks and stuff.

        It’s not a huge deal at the moment so I’m moving on to some of your other tutorials.


  11. Hi Erich,

    When i run this the progrtam gets stuck at while(!SD!_DataReceivedFlag){} in the SD1.c file. At the bottom of the SD1.c file is where the function is

    void SM1_OnBlockReceived(LDD_TUserData *UserDataPtr)
    /* Calling inherited event */

    I don’t understand this point from an earlier comment:
    “While SM1 is the SPI Object. This Function is in my Events.c and by including it via
    extern bool SD1_DataReceivedFlag;
    it now works. Maybe i overread it but i couldnt find it in the text. This info could be useful for others too.”

    Sorry but does this mean put extern bool SD1_DataReceivedFlag; in the Events.c file ? I’ve tried that without success. I’m very confused on this point…

    Thank you for the great work.

    • Hello,
      The flag should be defined in SD1.c:
      static volatile bool SD1_DataReceivedFlag = FALSE;

      So no need to re-add this.
      If you are stuck, then it very well could be that you have interrupts disabled, as things on the SPI side are interrupt driven.
      The SM1_OnBlockReceived() shall call the SD1_OnBlockReceived() which sets that flag.
      Have a look at the project on GitHub here:

      I hope this helps.

  12. Well I’m using the MKL25Z and i have the adafruit sd card shield. I see the flag defined in SD1.c so that is clear to me now thanks.

    In the CPU set up i can see that the init priority interrupts is enabled. The NMI interrupt is also enabled. However the NMI pin at PTA5 was not connected to the shield board. I am wondering should the PTA5 pin be connected to the CS pin which is located next to the L2, L1 pins used for the green/red LED ?

    I’ve tried the shell version you have and that didn’t work either so i probably haven’t connected all the pins from the shield and ARM board correctly :(

    • Hi Dean,
      are you running my project I have published on GitHub (
      Please try this project first as a reference point.
      I’m wondering why you think the PTA5 needs to be connected to the NMI? You can use the reset button on the FRDM board without any changes.
      And the CS pin of the SD card is connected to PTD0, and not to PTA5. Below is the pin assignment list I’m using.
      LED_GREEN [Output] => TSI0_CH12/PTB19/TPM2_CH1 [54]
      LED_RED [Output] => TSI0_CH11/PTB18/TPM2_CH0 [53]
      OpenSDA_RxD [Input] => TSI0_CH2/PTA1/UART0_RX/TPM2_CH0 [27]
      OpenSDA_RxD [Input] => TSI0_CH2/PTA1/UART0_RX/TPM2_CH0 [27]
      OpenSDA_TxD [Output] => TSI0_CH3/PTA2/UART0_TX/TPM2_CH1 [28]
      OpenSDA_TxD [Output] => TSI0_CH3/PTA2/UART0_TX/TPM2_CH1 [28]
      SD_CD => ADC0_SE6b/PTD5/SPI1_SCK/UART2_TX/TPM0_CH5 [78]
      SD_CLK [Output] => ADC0_SE5b/PTD1/SPI0_SCK/TPM0_CH1 [74]
      SD_MISO [Input] => PTD3/SPI0_MISO/UART2_TX/TPM0_CH3/SPI0_MOSI [76]
      SD_MOSI [Output] => PTD2/SPI0_MOSI/UART2_RX/TPM0_CH2/SPI0_MISO [75]
      SD_Shield_Green_LED [Output] => CMP0_IN3/PTC9/I2C0_SDA/TPM0_CH5 [66]
      SD_Shield_RED_LED [Output] => CMP0_IN2/PTC8/I2C0_SCL/TPM0_CH4 [65]
      SD_SS [Output] => PTD0/SPI0_PCS0/TPM0_CH0 [73]
      SD_WP => PTA13/TPM1_CH1 [33]

      I hope this helps.

  13. Hi yes I’ve downloaded the latest beans and drivers and running CW 10.4.I’m using the Freedom_FatFS with the shell as you suggest. I will double check the pin outs and see whether they match what you’ve just posted. I hope to resolve this issue, i’ll keep at it :)

  14. Hi Dean,

    Just wanted to chip in and say I, too, am using the Adafruit microSD card breakout and was able to get Erich’s example working with SPI0 (but not SPI1, for whatever reason). I remember getting stuck in that loop and seeing that comment about adding “extern …”, but that turned out to be a red herring. When I switched to SPI0 from SPI1, things just magically worked. I’m guessing you just have some pins mixed up.

    I also came up with a few FatFS projects from scratch just by following the instructions and they worked without any weird changes to the generated code or Events.c with the latest CW.


  15. Hi, I’ve checked the pin outs and everything matches. Vishal did you change the CD1 bit of the SD1 component from SPI1 to SPI0 ? i’m going to try a different SD card too, currently using a micro 1gb with an adaptor.

    All the best

    • Hi Dean,

      I currently have both CD and WP disabled and I don’t remember what I had set CD to but I’m pretty sure I followed Erich’s example directly (meaning PTD5 like his pinouts given in the reply above). If you’re concerned that this might be an issue, I’d suggest disabling the pins and seeing what happens. You shouldn’t have to change the code since the calls will just return true if the pins are disabled.

      Also, this is probably silly, but is the card formatted and all that? Do you have another MCU (like an Arduino) on which you can run a stock example to test read/write-ability?


  16. Hi, yes the SD card is FAT32 format and is ok as i can read/write fine to it. I’m using a newer SD shield which has SMD components for buffer then the one shown in the picture above. I’ve disabled the WP and CD pins but still no joy…. The MISO is on PTD3 and the MOSI is on PTD2, both are SPI0. The SS pin is PTD0 and is SPI0, I’ve also tried connecting this pin to the card select pin without any luck.

    Using the latest Freedom_FatFS from Github. This is what happens:

    Red SD LED turns on then turns off. ARM turn RGB LED flickers. No file created when checking the SD card.

    Humm I’ve tried two SD cards…. weird :)

  17. On the SM1:SPIMaster_LDD Component i’ve noticed ReceiveBlock and SM1_OnBlockReceived is greyed out I will check if the components are installed correctly, is this normal ?

    Thank you

      • Just one consideration: the SC card SPI clock is the same pin as the RGB blue LED. It works for me, but could it be that on your board this is causing issues? You might need to check the signals with an oszilloscope.

  18. Do you have the project and source with Generated_Code file available the github version doesn’t have that and perhaps i’m making mistakes in the setup.

  19. Hi Erich,

    Sorry to keep hammering on the comments section of this post.

    I’ve been debugging an SPI read/write issue and I narrowed down the problem to a part of the code where I was doing a SM1_SendBlock() without a call to SM1_ReceiveBlock() first. Simply adding the SM1_ReceiveBlock() call makes the code behave as expected. Is there some requirement that the rx data has to be read before new data arrives?

    To give you more details, I have turned SPI interrupts off to make debugging easier so I’m using polling to wait for data. The exact behavior I’m seeing is this:

    1. I send 10 bytes with SM1_SendBlock _without_ doing a SM1_ReceiveBlock; the response bytes are [0x02, 0x00, ...., 0x00], confirmed with a logic analyzer
    2. I then need to read 10 bytes, so I do a SM1_ReceiveBlock followed by a SM1_SendBlock to kick off the read (my MCU is an SPI Master); the response is again [0x02, 0x00, ..., 0x00], confirmed with a logic analyzer
    3. I busy wait for the received to complete, but when debugging, I see everything in the RX buffer offset by one byte; in other words, the data is [0x02, 0x02, 0x00, ...] so somehow the first byte is either stale or repeated.

    The offset behavior makes sense because when I call SM1_Main() (or the ISR() in the interrupt version), the RX status is checked first, and it is probably full from the write I did in step 1. This causes a read to immediately happen with (I think) stale data from the last write. I can see the ramifications of not clearing the RX buffer with a read, so I’m ok with this.

    The thing I can’t make sense of is that the offset byte is NOT the stale rx data from the last tx operation (0x00) – it is either the RX data from the VERY first write (0x02), or the RX data from the write that hasn’t happened yet (also 0x02)! I don’t think you would have any insight into my specific SPI peripheral, but my general question here is:

    if I don’t read the RX register, what sort of state should I expect it to have?

    I would expect it it to continually update as data is sent and received and I do see this behavior when stepping through in the debugger, however I can’t make sense of the last state the SPI1_D register is in just before step 2 (confirmed as 0x02). The logic analyzer claims the data is transmitting perfectly, so it’s definitely not sending 0x02 twice.

    I hope this mostly makes sense, and thanks in advance for taking the time to read.

    With interrupts enabled, I noticed that step 2 basically stalled and the ISR wasn’t getting called unless I set the SPI interrupt priority to HIGH. All this nondeterministic behavior is probably exacerbated by my use of the debugger…

    • The SPI is a shift register thing: you shift out things and get things shifted into on return. So yes, with the way how the Processor Expert driver is implemented, you need to do this in pairs of ReceiveBlock() and SendBlock(). If you are not interested in the either the rx or tx data, you can use dummy values. I had to do quite some tuning in the read/write operations as I need to be careful not to write to the tx registers if the previous data has not been sent yet, or to be careful not to read the rx register if the data has not been shifted in yet. I have pasted the code below I’m using in the SD card SPI driver:
      static volatile bool SD1_DataReceivedFlag = FALSE;

      void SD1_SPI_WRITE(unsigned char write) {
      unsigned char dummy;

      SD1_DataReceivedFlag = FALSE;
      (void)SM1_ReceiveBlock(SM1_DeviceData, &dummy, sizeof(dummy));
      (void)SM1_SendBlock(SM1_DeviceData, &write, sizeof(write));

      void SD1_SPI_WRITE_BLOCK(unsigned char *writeP, uint16_t size) {
      unsigned char dummy[4];
      uint16_t writeSize;

      while(size>0) {
      if (size>sizeof(dummy)) {
      writeSize = sizeof(dummy);
      } else {
      writeSize = size;
      SD1_DataReceivedFlag = FALSE;
      (void)SM1_ReceiveBlock(SM1_DeviceData, &dummy[0], writeSize);
      (void)SM1_SendBlock(SM1_DeviceData, writeP, writeSize);
      size -= writeSize;
      writeP += writeSize;

      void SD1_SPI_WRITE_READ(unsigned char write, unsigned char *readP) {
      SD1_DataReceivedFlag = FALSE;
      (void)SM1_ReceiveBlock(SM1_DeviceData, readP, 1);
      (void)SM1_SendBlock(SM1_DeviceData, &write, 1);

  20. Hi Erich,

    I connected up an oscilloscope to monitor the signals from the ARM board, I noticed quite a bit of ringing though coming from the sclk pin. I decided to get another sd card board, this is the new one i’ll be using:

    I’ve notice the frequency is correct on the scope for sclk at 375khz, the pulses seem to be in bursts of 8 then around 15us deadspot before giving out another cycle of pulses.. this repeats very briefly for the initial power on stage but then stops.

    The MOSI is outputting as well, and nothing is being returned on the MISO pin so i’m guessing the sd card board is caputs. I format the SD card to FAT32, i’m testing with two cards 1gb and 4gb.

    I’ll post if i make some progress :)

    Thank you for all your help


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  22. Hi Erich,

    I can debug this project without any error on code warrior, and its seems it works on the studio. But instead of the Arduino Data-Logger Shield, I just make my own simple connection to my SD card with the processor. But when I open the SD card on my computer, there is nothing written on it.

    Is it possible to use a simple SD card connection, and this project supposed to work? or do I have to add other things?


      • Hi Addis_a,
        yes, the signal for the blue RGB LED is as well the signal/pin for the SPI clock. If this is a problem, you might remove the blue LED resistor on the FRDM-KL25Z board.

    • Hi Addis_a,
      yes, you do not have to use the Arduino Data Logger shield, you can use any SD card, even on different pins. Simply change the pin settings. As for your project: are you actually writing to the card? My Freedom_FatFs project provides a shell to inspect/copy/list files, but does not actually write data files to it. That’s what your application has to do.

      • Hi Erich,

        Thanks for your replay, I really appreciate it! I want to copy files and if possible to read from it. But I tried your code and its not copying anything to my SD card.

    • I see that you have *very* long cables/wires. This will be for sure an issue for signal quality, expecially if you run the SPI at higher frequencies.
      Try to have them only few centimeters long.

      • Hi! I have shorten the length of the cable and tried the code now, nothing is copied into my SD card (even changing the SD card)
        I also tried the code from your Git (Freedom_FatFS) and it writes some commands on Tera term, and there were prompts asking me to enter code, but none of the commands worked. For example when I write cd command it printed.
        CMD> *** Failed or unknown command: cd
        *** Type help to get a list of available commands

  23. ERROR: getcwd failed: (12) The volume has no work area
    *** Failed or unknown command: FAT1 dir
    *** Type help to get a list of available commands

  24. I think its working now for FAT1 diskinfo command; it printed:
    SDC version : SDC ver 1.XX or MMC
    Sector count : 3854336
    Sector size : 512
    READ_BL_LEN : 1024
    Block size : 8192
    CSD : 00 2E 00 32 5B 5A A3 AC FF FF FF 80 0A 80 00 7F
    CID : 02 54 4D 53 41 30 32 47 05 12 95 99 E4 00 AC 43
    Manufacturer SA02G
    Serial Number 9599E40
    OCR : 80 FF 80 00
    SD Status : 00 00 00 00 00 00 00 28 02 02 90 01 00 AA 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

    But not for FAT1 dir and the other commands, I couldnt be able to delete a file also.
    But I will continue trying, and since its not telling me the directory, what do you suggest to enter in place of the src and des address: copy FAT1
    For example if I want to copy a file(txt.txt) from the computer to the sd card.

    Thanks for your help!!!

  25. So it looks like you can communicate with the SD card :-). You need to mount the volume first before you can use it. See FAT1_CheckCardPresence() implementation which checks the ‘card presence’ pin and mounts and unmounts the file system.

    • diskinfo accesses the disk on a very low (block) level. dir, copy, delete and so on are high level commands on the file system, so you need that file system mounted first.

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  27. Dear Erich,

    Thanks for all info posted in this site.
    I’m working with JM60 family. Could be adapted this project to this family?
    Could be used LDD components with HCS08 families?

    Best regards

    • Hi Javier,
      yes, you can easily adapt this project for the JM60 family. Create a new project with the ‘new project wizard’, and then add the components. You just need to make sure you select the right pins (depends on your board), and configure the SPI properly. Check as well the Events.c of the Kl25Z project about how the events are used.
      And no, you cannot use LDD components with the HCS08. But the componets I have created deal with this, no worries.

  28. Hi Erich;
    I developed a product using KL25Z, FAT_FileSystem, SD_Card and GenericTimeDate, set up the current time in GenericTimeDate as 15:23:42.00, after a second read the current time, but the value returned is not 15:23:43.00, is this correct? I developed a routine that returns me the right time, however when I replace the code, it is rewritten by compilation or software crashes.

    Thank you, Charles

      • Hi Erich;
        I have a timer from 50ms, then changed the tick time from 10ms to 50ms in GenericDateTim, in 50ms timer interrupt was added to the command line ‘TmDt1_AddTick ();’

        Following the formulas ‘TmDt1_GetTime (TIMEREC * Time)’, I used Excel to calculate the values ​​of hour, minute, second, the values ​​are identical, however wrong, then developed my own code and I get the time, below my code

        Var1 = TotalHthH;
        Time->Hour = (byte)(Var1 / (3600 * TmDt1_TICKS_PER_S));
        Var1 %= (3600 * TmDt1_TICKS_PER_S);
        Time->Min = (byte)(Var1 / (60 * TmDt1_TICKS_PER_S));
        Var1 %= (60 * TmDt1_TICKS_PER_S);
        Time->Sec = (byte)(Var1 / TmDt1_TICKS_PER_S);
        Time->Sec100 = (byte)((Var1 % TmDt1_TICKS_PER_S) * (TmDt1_TICK_TIME_MS / 10));

        Tanks, Charles

      • Hi Charles,
        I’m using that GenericTimeDate component in many projects (typically with a 10ms tick), and I have not seen any issues so far. And I would think that my time calculation is correct too? Not sure what is wrong on your side. Maybe your timer interrupt is not firing correctly? Maybe your timer interrupt is a low power interrupt timer which only runs in low power mode? Can you use the same timer as I used in

      • I downloaded the project and import into 10.4 CW, tomorrow I will test the equipment.


      • Hi Erich;

        I tested values ​​using the Excel table, actually using the tick time as 10ms, the time is right, if I change the value of tick time for any other, the error occurs and the time is wrong

        Thank you for your attention


      • Hi Charles,
        now I see your point: my code really only works for 10 ms ticks :-(. Your code looks fine, and I want to do some tests today
        I was thinking to have TotalaHthL always counting the number of 10 ms ticks: for the case of 50 ms ticks it would increment the counter by 5 for every interrupt.
        I need to compare different solutions.

        Many thanks!

      • Hi Erich;
        I’m glad I could help, if you can send me the file. PEupd, or upgrade your site to download would be great.


    • Hi Erich;
      Yesterday I downloaded the file. PEupd and updated my code, is working perfectly. I will definitely use this component in other projects.
      if a problem occurs I warn you.


  29. Hy Erich,
    I’m using your SD card component to develop a data logger with the FRDM-KL25Z board.

    I’ve noticed that there’s an issue with the CS line management with my SD card (I’m using a new 2GB SD card that I think be a SDv2 card). The problem arise when is called the function disk_initialize. When is sent the ACMD41 command the data out line remain always high and the execution stops in the wait for leaving idle state loop.

    The unique way for get the correct answer from the SD card and go forward with the execution is to release the CS line at the end of the SendCmd function but, with this modify, the SD card doesn’t respond correctly when the functions disk_write and disk_read are called.

    Do you have any suggestion on the way to use to solve this problem? I’m thinking to copy the files generated by the processor expert in the source folder and then create a specific SendCmd function for the initialization phase.

    Thak a lot for your work and my best regards,

      • Hi Erich,
        problem solved! A stupid problem ad a good lesson for me.

        The problem was that I connected the VDD pin of the SD card to an output pin of the KL25Z MCU. When the internal init cycle of the SD card starts the supply voltage goes below the minimum operating voltage and the card will reset.

        Now the SD card starts but, after the initialization phase, when I try to read the writed datas contained in the card to pass these datas to a PC trough the USB configured as MSD device, the firmware will reamain stuck in the wait cycle of this function:

        void SD1_SPI_WRITE(unsigned char write) {
        unsigned char dummy;

        SD1_DataReceivedFlag = FALSE;
        (void)SM1_ReceiveBlock(SM1_DeviceData, &dummy, sizeof(dummy));
        (void)SM1_SendBlock(SM1_DeviceData, &write, sizeof(write));

        I’ve read all the previous comment but any of these has helped me for now…

        Hi, Walter

      • Hi Walter,
        if you are stuck in this code, this probably means your interrupts are not enabled. Can you check that you have not interrupts disabled?


  30. Hi Erich,
    also I think that the problem is related to the interrupts state. I’m using a modified version of the MSD demo firmware from Freescale.

    The problem is when I connect the USB to the host PC and the firmware goes in the read request section of the MSD event callback routine. For this reason I don’t know well the state of the interrupts at this point of the firmware.

    Yesterday I’ve tried to use the __EI(); instruction before the SendCommand(CMD18,LBA_ADDRESS) instruction but it didn’t work.

    I also tried to move the read block instruction in the main routine of the firmware to try this part without the MSD event callback routine but the problem persist.

    I’ve a 4 channel DSO for monitor the SPI signals and when the SD1_SPI_WRITE(DUMMY) of the WaitReady function is called, no SPI signal is generated by the MCU (I don’t see even the clock signal).

    The most odd thing is that in the SD card init phase triggered by the f_mount or by the f_mkfs instruction the SPI works fine. Also with the f_open instruction and the f_close the SPI works fine. But when I want to read a single block directly from the SD card the SPI don’t works.

    For read a single block out from the FatFs functions I use this code:

    (void)SD1_SendCmd(SD1_CMD18, LBA_ADD);
    (void)SD1_ReceiveDataBlock(data_buff, 512);
    (void)SD1_SendCmd(SD1_CMD12, 0);


    • Hi Walter,
      I’m little bit lost if you use another (modified) firmware. I guess it will be really hard for me to help you remotely. I suggest that you use the example I have provided on GitHub and compare with this one?

  31. Hi man, I’ve got two problems when i run your project Freedom_FatFS from github repository. I get the following warn: Invalid project path: Include path not found C:\Users\workspace\Freedom_FatFS\Generated_Code).

    If I ignore this and compile then i see lots of errors cpu.h not found ect.

    When i import this project do i need to turn the self generation off for the components to prevent settings from being changed in my work space?

    Many Thanks

    • Hi, I solved the first error by simply importing the project again.

      It seemed to execute just fine, and the sd led on the shield indicated process was writing, after writing the RBG led on the ARM flickered through happily :)

      However, when i check the sd card afterwards no file was created :(

      The sd card is using the FAT filing system is that correct ?

    • If you import that project, then that ‘Generated_Code’ directory does not exist yet, so you need to generate Processor Expert code first. Then this warning should go away.

      • Hi, I’m just using the example code from above

        if (FAT1_open(&fp, “./test.txt”, FA_CREATE_ALWAYS|FA_WRITE)!=FR_OK) { /* open file, will always create it if not already on disk */
        for(;;){} /* error! */
        if (FAT1_write(&fp, “Hello World!”, sizeof(“Hello World!”)-1, &bw)!=FR_OK) { /* write string to file */

        So i guess this should create a file called test.txt on the SD card with “Hello World!” written once ?

        Or does this example allow for reading from a txt file but not writing too the file ?


  32. Yeah in the example code above it clearly says

    /* open file, will always create it if not already on disk */
    /* write string to file */

    It’s the Freedom_FatFS project from that i’m running.

    Since the program seems to mount, then unmount (indicated by leds) i would think it’s trying to write file but unsuccessfully…

    • Yes, this is how it is supposed to work (and works on my side). If it does not work that way, then you have to check it with the debugger to see what is going on.

      • Yeah, I trust in the code and components. So i think it’s something to do with the code warrior setup my end. It is why i asked about the component generation and whether it should be disabled to prevent automatic changes from PE when building.

        Humm I’ve only really followed your guidance through these tutorials which i think are amazing :)

        So perhaps broadly speaking the skills required in embedded programming and development troubleshooting ect are perhaps my weak spot. Do you recommend any good books, sources that focus specifically on these skill sets ?

        Many thanks
        I hope to make some progress soon.

  33. Hi, I finally got this working

    Turned out the board had some bad solder joints on the sd card shield. I basically re-flowed the board and it sprung into life !

    I managed to communicate over CDC using tera term and see the diskinfo ect. I then ran FAT1 benchmark and got my first successful write :)

    I’m glad i didn’t give up but i’ve had many distractions hence the long delay since the first post.

    Thanks Erich your the man !

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  35. Hi Erich,

    I’m currently working on a similar project on the KL46z. I used most of what you had, changing a few pins to account for ones I had already used, but nothing drastic. Right now I’m in the process of debugging, as I kept timing out in the FAT1_open section. I removed the AddTick from my interrupt to see exactly where the timeout was happening and it looks like it’s when the IDLE command is sent during the SD card initialization sequence. It is sending and receiving data, as it isn’t hanging on the (!SD1_DataReceivedFlag).

    Do you have any immediate thoughts on what could be going wrong?


    • Hi Ethan,
      that sounds like the SD card does not respond. Try to re-power the card (remove an insert it again). Check the wirings (are all the pins correctly assigned/used). Use a logic analyzer and check the signals and frequency of signals: the clock shall be below 375 kHz during the intialization.

      I hope this helps,

      • I did some looking with a logic analyzer and it looks like some of my lines are dead sometimes, and working others? I’m completely confused. It looks the the CS*/SS line is always working/toggling as expected, but the clock line/MISO line are stuck at logic 0.

        I’ve done some digging online and it looks like I should be using pull ups, which I currently am not. Is there any issue with me doing this via PE and chip sharing? I remember you doing this in one of your other posts.

        I will also be rechecking my connections and wiring, as that is always a concern.

        Thanks for your help,

      • After more troubleshooting I have it taken care of. The reason some of my lines were dead was because I was attached to the wrong lines! I’ve been working with a KL25z and a KL46z. In a stupid mistake I was looking at the pinout for the KL25z instead of the KL46z. I didn’t catch it earlier as all other parts were working (right side of J4 header, and some pins on the J1 header).
        A very hearty thank you for all the work you do on this site, it’s been a godsend in learning how to use the freescale boards.

        Best regards,

      • Hi Ethan,
        good to hear that the problems have been sorted out. Yes, the physical layer is causing problem too many times ….

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