I recently had to make a field upgrade to the software on some ESP32-based devices. I didn’t want to have to require that the operator go through the entire process of installing the Arduino IDE, download libraries, and all that not-so-fun stuff. For us techies, it’s no big deal. For a non-technical user who has tons of more important things to do, it becomes a royal pain in the butt.
So, what to do? From watching the IDE output, I could see that it called esptool.exe. A bit of research into this tool and it looked like the only problem we were likely to run into was figuring out which virtual COM port had been assigned to the device. Also, since there were a number of these units to reprogram, it needed to be efficient.
Enter the chgport command. chgport lets you change port settings, but for my purposes the most important part was that it lists the COM ports connected to the PC.
I could redirect the output from chgport to a file, then parse that file and supply esptool with the COM port of the device. After verifying this manually, I went forward and built this script.
set BOOT=PROGRAM.ino.bootloader.bin
set PART=PROGRAM.ino.partitions.bin
set PROG=PROGRAM.ino.m5stack_core2.bin
set APP=boot_app0.bin
chgport > port.txt
set /p PORTLINE= < port.txt
set PORTNAME=%PORTLINE:~0,5%
echo %PORTNAME%
esptool.exe --chip esp32 --port %PORTNAME% --baud 921600 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 80m --flash_size 16MB 0x1000 %BOOT% 0x8000 %PART% 0xe000 %APP% 0x10000 %PROG%
pause
The name of the actual file programmed into the M5Stack device was replaced above by “PROGRAM.ino” Telling the IDE to save the compiled binary will put this file, along with the bootloader and partition configuration into your current working directory.
Next, you can see that we redirect the output of chgport to a file, then set a variable PORTLINE to the content of that file. The next line strips out the first 5 characters and stores it in the PORTNAME variable. This imposes an important requirement for using this batch script: the Arduino device must be the only, or at least the first, COM port in the file. It’s possible to work around this limitation, but it would require a more complex batch file, or perhaps even a Python script or similar.
Assuming we can successfully get the COM port, the next line calls the esptool with the necessary parameters and the device is programmed. I added a “pause” command so the user can see the result of the script before the window disappears.
There you have it. HTH!
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