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Establishing serial communication over UART instead of USB in MAX25405 EVKIT

rsjawale24

The MAX25405EVKIT comes with a MAX32620FTHR board which is preprogrammed with custom binary file for the gesture recognition. The application note at Maxim Gesture Sensor EVKit Serial API (maximintegrated.com)

mentions "The serial interface can be implemented over the Universal Serial Bus (USB) virtual serial port or over a Universal Asynchronous Receiver-Transmitter (UART). The EV kit is shipped configured to use the USB serial port to work with the EV kit PC Graphical user Interface (GUI). If a UART serial interface is desired, custom firmware in binary format is available."

Upon researching more, I found the firmware_framework code that contains the code for gesture recognition compiled using mbed compiler.

The readme file says that a file called interface.h and interface.c define the communication protocol. When I open the interface.c file, I can see a comment in the code that says Option to implement serial API over UART instead of USB but there is only a MACRO set as #define macro_name 0 

I tried to change the 0 to 1 and compile the code, however, it does not compile successfully. The USBDevice library shows some error while compiling. 

Did anyone try to change the serial API over UART instead of USB? Was it successful?  

EDIT: I have successfully compiled the code for UART. However, I'll do some experiments and write introductory blogs before I re-program the MAX32620FTHR board with my firmware. 

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  • I am curious how did you successfully compiled non-changed code? I started working with latest mbed-os but I was unable to compile it (missing toolchain) no matter of USE_UART_INTERFACE setting. Later I found some other issues on internet and general recommendation is downgrade mbed-os because Maxim do not update their codes to last mbed-os and their codes currently do not work with latest mbed-os. After downgrading I was able to successfully compile with USE_UART_INTERFACE set to both 0 and 1.

    I compiled this using following steps. Especially see git checkout which downgrades the mbed-os and description for vim commands in which I had to fix one old py file to work with latest python libraries.

    sudo apt update
sudo apt install python3 python3-pip git mercurial
python3 -m pip install mbed-cli

unzip firmware_framework.zip
rm firmware_framework.zip
mbed new .
mbed add https://os.mbed.com/teams/MaximIntegrated/code/MAX32620FTHR/
mbed add https://os.mbed.com/teams/MaximIntegrated/code/USBDevice/

# add main stack limit section according to readme.txt
vim mbed_app.json

# download ARM GNU Toolchain from https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
tar -xf arm-gnu-toolchain-12.2.mpacbti-bet1-x86_64-arm-none-eabi.tar.xz
export MBED_GCC_ARM_PATH=/home/michal/armgcc/arm-gnu-toolchain-12.2.mpacbti-bet1-x86_64-arm-none-eabi/bin

cd mbed-os
git checkout 0fdfcf7350896a9c0b57c4a18237677abfe25f1a

# in following vim window change following line:
#
# from collections import namedtuple, Mapping
#
# to followiong two lines:
#
# from collections import namedtuple
# from collections.abc import Mapping

vim "/home/michal/max25405fw/mbed-os/tools/targets/__init__.py"

mbed compile -m MAX32620FTHR -t GCC_ARM

    After this I was able to get firmware compiled with both USE_UART_INTERFACE=0 and 1. I currently do not have enough time to test built firmwares. I will test them next weekend. Before flashing I recommend backuping stock firmware. I have not checked on this yet but Maxim usually do not lock MCU for prevent reading stock firmware, so you should be able to download stock firmware from MCU before flashing custom firmware. You should be able to do this using JTAG probe and openocd. Note that vanilla/mainline openocd usually do not work with Maxim MCUs (or at least It never work on my machine and chip). Use their patched openocd which is available as part of their SDKs available at pages of MCUs. As I said, currently I have no time to test it, but next week I will try it and give you better feedback.

  • in reply to misaz

    I'm curious to know which version of Mbed did you downgrade to as I too could not get it to work with latest version.

    Did you backup stock firmware? I had assumed there was a binary available but alas there was none.

    Just to say that I found a fix for the USBserial (tested version 6.15/6.16), which I highlighted on GitHub ARMmbed issues page: https://github.com/ARMmbed/mbed-os/issues/15334

Reply Children
  • in reply to BigG

    The readme file in the framework suggest to use this command

    mbed new . --scm none

    mbed new .
    Use the "--scm none" option to prevent revision control initialization

    Unfortunately, no binary is available for the original firmware. If you have a backup, request you to please share the binary file as I already flashed my MCU with UART firmware 

  • in reply to BigG

    It is written in command list which I posted. It is following line:

    cd mbed-os
git checkout 0fdfcf7350896a9c0b57c4a18237677abfe25f1a

    I found this commit ID somewhere on the internet. Someone was facing simmilar issue but with different firmware and library. I tried it and I was able to compile firmware with this version. But I had to fixed one old python script which come from this old mbed-os. See comments in code snippet in my previous comment.

    Currently I am out of home. I will of course try backup stock firmware before flashing my own. I always do this when possible. I will try this with MAX32620FTHR next weekend. If you want to do it yourself, you can use some of following commands. They come from my notes which comes from my last attemps of backuping firmware from MAX32625PICO board by other debug probe. Note that I recommend using openocd bundled as part of Maxim SDK (from C:\Maxim\... directory). In my case mainline openocd never worked with their chips. Last time I faces issue when mainline openocd successfully erased my MAX32625MCU but was unable to program new firmware (efficiently it bricked my MCU). Most probably Maxim patched openocd somehow to support their MCUs better. Following commands I post without any warranty. Since I am out of home I cant test that they work with MAX32625FTHR also.

    "C:\Maxim\Toolchain\bin\openocd.exe" -s C:\Maxim\Toolchain\share\openocd\scripts -f "path to config probe depending on debug probe used (ST-Link, J-Link, MAX32625PICO, ...)" -f target\max32625.cfg -c "reset"

    After connecting to target open putty and connect using telnet to localhost:<telnet port which can be determined from openocd output>. In telnet window execute:

    halt
dump_image max_stock_fw.bin 0x00000000 0x00200000

    max_stock_fw.bin willget created in working directory. Run dump_image three time with different file names and after dumping check that all three files are the same and no bit error occured when transfering firmware.

  • in reply to rsjawale24

    I did it without --scm none but I think this has no impact on result. I think scm means that it initializes git repo for your project but I think it has no impact on operating system which is always downloaded using git.

  • in reply to rsjawale24

    Yes I have tried mbed new . --scm none but it did not work. I believe this just relates to version control. I believe has the solution with git checkout 0fdf...

    I don't have a backup either.