The STM32 microcontroller has a built-in bootloader that is capable of updating the user flash over USART1. See AN2606 for details.
On the Chameleon v3, the signals needed to enter and exit bootloader mode can be controlled over a USB connection. This document describes a utility that resets the STM32 into bootloader or user flash mode.
On the Chameleon v3, the BOOT[1:0] and RST_L signals are connected to the CBUS[2:0] pins on the FT232R. These pins must be programmed as GPIO; see Chameleon V3 Proto0 Care and Feeding document.
libgpiod to access the FT232R CBUS pins as GPIO pins from user space.
gpiod and the development libraries.
$ sudo apt-get install gpiod libgpiod-dev
gpiodetect to verify that the libraries correctly detect the FT232R.
$ sudo gpiodetect gpiochip0 [ftdi-cbus] (4 lines) $ sudo gpioinfo 0 gpiochip0 - 4 lines: line 0: unnamed unused input active-high line 1: unnamed unused input active-high line 2: unnamed unused input active-high line 3: unnamed unused input active-high
~/chromiumos/src/platform/chameleon/utils/stm32reset$ make gcc -Wall -Wextra -g -std=gnu89 -o stm32reset stm32reset.c -l gpiod
To reset the STM32 into bootloader mode, run
stm32reset --bootloader. The STM32 will remain in bootloader mode until it is reset (or power cycled).
$ sudo ./stm32reset --bootloader $ stm32flash /dev/ttyUSB0 stm32flash 0.5 http://stm32flash.sourceforge.net/ Interface serial_posix: 57600 8E1 Version : 0x30 Option 1 : 0x00 Option 2 : 0x00 Device ID : 0x0430 (STM32F10xxx XL-density) - RAM : 96KiB (2048b reserved by bootloader) - Flash : 1024KiB (size first sector: 2x2048) - Option RAM : 16b - System RAM : 6KiB
stm32flash expects to communicate with the flash bootloader. When the program in user flash is running,
stm32flash will report a failure to initialize.
$ sudo ./stm32reset --user $ stm32flash /dev/ttyUSB0 stm32flash 0.5 http://stm32flash.sourceforge.net/ Interface serial_posix: 57600 8E1 Failed to init device.
If you have more than one FT232R plugged into your computer, determine which device is the Chameleon v3. It should have entries in
gpiochipn. The n is the device number to pass to
stm32reset with the