Sometimes I think that a problem should be solvable in a few minutes, and then it turns out that it lingers around for months. Very, very frustrating! Such a thing is getting the USB 4.1.1 stack running on the FRDM-K64F board. I have that board since April 2014, and it took me 7 months to get the FSL USB stack running on it :-(.
FRDM-K64F Board
How cool would it be to add WiFi support to any projects or IoT? Why not using WiFi with a microcontroller which has only few KBytes of RAM and FLASH. For less than US$5? Dreams came true, and intrigued by an article at Hack-A-Day, I searched a supplier for that ESP8266 module. And this evening I have found the four ESP8266 modules I have ordered for $4.50 each from ElectroDragon in my mailbox. Of course I did not want to wait for the week-end, so I hooked it up to my FRDM-KL25Z board.
ESP8266 Module for US$ 4.50
There are two basic strategies in teaching:
I usually do the first method. But there is a lot of value in the second method too!
When I asked all student groups to solder the headers on the Freescale FRDM-KL25Z board, I received one report that the board does not work any more. A quick inspection of the board showed this:
How NOT to Solder the FRDM Board Headers
Found an interesting behaviour with the Freescale FXOS8700CQ on the new Sumo Robots (see “Sensor and Communication Shield for Sumo Robot“): when enabling the accelerometer/magnetometer, it actually did not work:
Failed to Enable FXOS8700 Accelerometer
Sunday morning started at 7am in a good way: I think the sun guessed already that I want fire up my smoker today.
Morning Ready to Smoke
❗ And no, that’s not the smoker in that picture! That’s ground fog in the morning (see “Inversion“).
Ready to continue my week-end project: DIY Smoked Beef Brisked!
While my beef brisket (see “My First DIY Smoked Beef Brisket: Day 1“) is smoking on ;-), I have time to investigate a problem I was running on in my lecture on Friday: For the Joystick shield (see “JoyStick Shield with the FRDM Board“) on the FRDM-KL25Z board, I wanted to use an interrupt if I press the green button:
No Interrupts for Button C
However, that did not work :-(.
Ahhhh, I truly love the Texas BBQ (see “BBQ Smoker Monitoring Robot“)! And what I love the most is Beef Brisket. Unfortunately, I cannot travel each time to the US to get some brisket. So good or bad, I have to make the brisket myself :-). The challenge is that outside of Texas, ‘Brisket’ probably is an unknown thing, especially in my area. In the usual grocery stores and supermarket, if I ask for a brisket, they they just shake their heads and ask “brisket what?”. Of course, my local butcher (Messerli, Metzger meines Vertrauens!) in Steinen knew exactly what I need for a Brisket :-): a special cut of beef from the lower chest of beef.
On Tuesday, I sent my wife to pre-order my cut of beef, and this morning we picked it up in the butcher’s store. An excellent piece, already trimmed, 1.662 kg:
Raw Beef Brisket
Sometimes, there are ugly bugs in tools, and without knowing about them, it is likely to spend hours and hours, and of course to be frustrated. Knowing about these issues does not remove the issue, but at least helps to cut time to deal with it. And here is one which was nagging on me for a while with the GNU GDB debugger in Eclipse…..
💡 I have used the Q4 2014 GNU ARM Embedded (launchpad) toolsuite/gdb (4.9-2014-q4-major), and I have found that with that gdb version the issue described is fixed. If you are using Kinetis Design Studio, see “Switching ARM GNU Tool Chain and Libraries in Kinetis Design Studio” how to upgrade the tool chain.
I was happily debugging my project, making some changes, and suddenly I cannot debug it any more. What happens is that I can download the binary with GDB, but it immediately terminates and disconnects:
Terminating Gracefully Target Disconnected
After digging and doing some trial and errors, I have found what is causing this.
Initializing. Target has been RESET and is active. Disconnected from "127.0.0.1" via 127.0.0.1 Terminating Gracefully... Target Disconnected.
The GNU Linker (ld) is very, very powerful. This time I wanted to put all my Processor Expert generated code into its own dedicated section. This is useful for example to have a bootloader or a library inside a special area in FLASH. It was not obvious to me how to do this with the linker, with some search on the internet and some trial and errors, I finally managed that. And as always with exploring things, I have learnt something :-). So here is how I’m able to put the code of arbitrary files into its own dedicated section.
Code Section for Generated Code
When using a bootloader (see “Serial Bootloader for the Freedom Board with Processor Expert“), then I usually protect the bootloader FLASH areas, so it does not get accidentally erased by the application ;-). When programming my boards with the P&E Multilink, then the P&E firmware will automatically unlock and erase the chip. That’s not the same if working with the Segger J-Link, as it but requires extra steps.
Protected FLASH Pages with Processor Expert
MCU on Eclipse 