Q&A

Everything you always wanted to know about Eclipse, Embedded Systems Programming, Software and Tools, or any topics of this blog, but where afraid to ask, then this page is for you.

Post a comment, and you might get an answer, either from myself or from the readers of this blog. Otherwise: the answer is always ‘42‘ 😉

For feature requests or bug reports on the McuOnEclipse project end Processor Expert components, you should use the GitHub issue tracking system:

McuOnEclipse Processor Expert components: https://github.com/ErichStyger/McuOnEclipse_PEx/issues
McuOneEclipse example projects: https://github.com/ErichStyger/mcuoneclipse/issues

837 thoughts on “Q&A”

Etienne on December 5, 2017 at 19:30 said:

Hi Erich! great work on his blog ! I’ll use some of your code inside my project ! Quick question about the freeRTOS PE component. I seem to get lost with the priority scheme of freeRTOS, interrupt and your implementation of the freeRTOS component.

I want to be sure of one thing : IDLE task is assigned priotity 0, I guess it’S the lowest priority, the priority we give in FRTOS1_xTaskCreate() (PE component) should be related to priority number of the free RTOS right ? not the priority of the interrupt.. which are inverted right ?

lets says i create 2 tasks with your component :
FRTOS1_xTaskCreate(tsk1, “Task1”, configMINIMAL_STACK_SIZE, &globalhost, 1, NULL);
FRTOS1_xTaskCreate(tsk2, “Task2”, configMINIMAL_STACK_SIZE, &globalhost, 2, NULL);

Task2 priority will be greater than Task1 ?

sincerely.

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- Erich Styger on December 5, 2017 at 20:15 said:
  
  Hi Etienne,
  the FreeRTOS component is using the normal FreeRTOS priority scheme (nothing different). If you are new to FreeRTOS and the ARM Cortex interrupts, then I recommend that you have a read at the multipart tutorial starting at https://mcuoneclipse.com/2016/08/14/arm-cortex-m-interrupts-and-freertos-part-1/.
  Keep in mind that FreeRTOS priorities start with zero as the lowest priority, while the ARM Cortex priorities have zero as the highest urgency level.
  So yes, 0 (or tskIDLE_PRIORITY) is the FreeRTOS priority for the IDLE task. The RTOS itself runs with its interrupts (SysTick, PendSV and PendSvReq) at the lowest interrupt priority (15 for 4 priority bits).
  And yes, for your example, the Task2 his higher urgency than Task1 and this one has higher urgency than the IDLE task.
  I hope this helps,
  Erich
  
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Soo-Chang, Lee on December 18, 2017 at 09:30 said:

Hello, Erich! I really ensjoy your blog!

I have a question about mbed, especially openSDA.
I build a board based on FRDM-KL43Z.
My trouble is my boards are doesn’t work in my PC. I think absent of bootloader is main problem. Can you teach me how install a new bootloader in a board? There is none-S/W in my board.

Here is my board symptom.
1. Power LED is working
2. MCU USB port ack as USB serial. But it cannot use as storage.
3. openSDA USB unack.

sincerely,
Soo-Chang

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- Erich Styger on December 18, 2017 at 12:02 said:
  
  Hi Soo-Chang,
  have a read at https://mcuoneclipse.com/2014/11/01/illustrated-step-by-step-instructions-updating-the-freescale-freedom-board-firmware/ how to update the bootloader/application.
  If you are using Windows 8 or 10, then have a read at https://mcuoneclipse.com/2016/08/01/bricking_and_recovering_opensda_boards_in_windows_8_and_10/ too.
  I hope this helps,
  Erich
  
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  - Soo-Chang, Lee on December 21, 2017 at 01:45 said:
    
    Hello again.
    
    I tried your guide. But it is different situation.
    My board flash is empty. So it doesen’t work as a writable device.
    
    Anyway I really appreciate of your advice again.
    
    sincerely Soo-Chang
    
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    - Erich Styger on December 21, 2017 at 08:39 said:
      
      Your openSDA/K20 is programmed, right? It does not matter if your KL43Z is empty or not: the K20 will programm it, no matter what.
      
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  - Soo-Chang, Lee on December 22, 2017 at 01:02 said:
    
    Actually, I’m not sure about that. I made my own PCB based on KL43Z. I used new K20. I think OpenSDA/K20 is not programmed as well. I don’t have any S/W in my board.
    I think the only way to install the bootloader is using jtag.
    
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    - Erich Styger on December 22, 2017 at 20:01 said:
      
      Ah, I see, I thought you are talking about the FRDM-KL43Z. So yes, if you have a board with a new K20DX128 chip, you need to program it first with the bootloader. E.g. in a way described in https://mcuoneclipse.com/2016/06/26/how-to-recover-the-opensda-v2-x-bootloader/
      
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- Soo-Chang, Lee on December 29, 2017 at 02:55 said:
  
  Thank you, Erich!
  I will follow your advice. Thankyou again!
  I will update my data later.
  
  P.S. Happy new year!
  
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NealXu on January 24, 2018 at 18:11 said:

Hi…in my case my boards are doesn’t work in my PC. I think absent of bootloader is main problem. Can you teach me how install a new bootloader in a board? There is none-S/W in my board.

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- Erich Styger on January 25, 2018 at 08:46 said:
  
  That depends on the board. Which board are you using? Otherwise have a read at https://mcuoneclipse.com/2014/11/01/illustrated-step-by-step-instructions-updating-the-freescale-freedom-board-firmware/
  I hope this helps,
  Erich
  
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brynn rogers on March 7, 2018 at 20:20 said:

Hi Erich,
I just noticed that NXP has a Low Voltage Hbridge PE component (LVHBridge) , and also a medium voltage Hbridge (MVHBridge) component that can be downloaded and work on processors like the K20’s with Processor Expert. Have you seen these before and do you have any experience with them?
I found it because I want to make a stepper motor driver (microstepping) using discrete components on the theory that it could be better/cheaper than using a microstepping chip- these components look like the easy way to do so.

Brynn

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- Erich Styger on March 7, 2018 at 21:09 said:
  
  I have no experience with these components.
  
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Eli Naiman on April 7, 2018 at 16:18 said:

Hi Erich,
I am working on a project where I send short text messages between a K64F and an android tablet. I want the K64F to be a host and the tablet to be a device. How do I do this. Do I need an OTG cable.

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- Erich Styger on April 8, 2018 at 17:39 said:
  
  Hi Eli,
  the means that the K64F needs to be in host mode. If you are using the FRDM-K64F board, then this is not supported out of the box. Basically you need to supply 5V from the board to the tablet. See https://mcuoneclipse.com/2012/10/15/usb-host-mode-hack-for-the-freedom-kl25z-board/ and https://mcuoneclipse.com/2013/03/02/usb-msd-host-for-the-freedom-board/. The bigger thing is that you need a USB CDC host implementation running on the K64F. I had this on my ‘wish list’ for a very long time, but never got to the point to have the USB stack working that way. You might need to check the latest NXP MCUXpresso SDK if it supports what you need?
  
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Eli Naiman on April 15, 2018 at 21:43 said:

Hi Erich
I am trying to modify your example using the Adafruit SPI friend. I want to use the Freedom K64F instead of the Tiny20.

For the Adafruit SPI you use 5 IO lines. I want to use the Adafruit UART friend, no interrupt and the CS tied to GND. This will use up only 2 IO lines.

Will this work?

Thanks
Eli

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- Erich Styger on April 16, 2018 at 08:16 said:
  
  Using the K64F instead the K20 should be pretty straight forward. But there is no CS line on the UART friend (https://www.adafruit.com/product/2479)?
  Keep in mind that for the UART friend you have to use UART hardware flow control, and not every UART peripheral might support that. From that perspective, the SPI BLE Friend is much easier to use imho.
  
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