nabil.me

Programming the STM32F4 DISCOVERY with the Bus Blaster

November 1, 2011 #electronics

STM32 and bus blaster

In my last post I covered setting up a toolchain on macOS. In this post, I’ll show how to program and debug the STM32F4 Discovery board using open source tools and hardware.

The Discovery board supports ARM's two-wire SWD and six-wire JTAG debug ports. While ST provides official programmers, they lack Linux support. Fortunately, their dev boards include an ST-LINK USB-to-JTAG translator, which now has Linux support thanks to texane on GitHub. There's also a fork adding STM32F4 support, though it's still a bit unstable. So, let’s look at an altern...

Bus Blaster and OpenOCD

⚠️ Warning: OpenOCD doesn’t fully support Cortex-M4 yet. This method could damage your hardware. Use at your own risk.

The Bus Blaster is an open hardware JTAG debugger available from SeeedStudio for about $35. Any debugger compatible with OpenOCD should work with these instructions.

Download OpenOCD 0.5.0 from SourceForge, extract it, and run:

cd [OpenOCD]
CC=/usr/bin/gcc-4.2 CPP=/usr/bin/cpp-4.2 CXX=/usr/bin/g++-4.2 LD=/usr/bin/ld ./configure --prefix=/opt/local/ --enable-ft2232_libftdi
make
sudo make install

Download the STM32F4 Demo

Update: You’ll need to update LDFLAGS, CC, LD, etc. in the Makefile to match your system.

git clone https://github.com/nabilt/STM32F4-Discovery-Firmware.git
cd STM32F4-Discovery_FW_V1.0.1/Project/IO_Toggle
make

JTAG pinout Discovery board
JTAG pinout Discovery board

Connect all six JTAG pins from the Bus Blaster to the Discovery board. TDI is located at pin PA15 on header P2.
Important: Power the Discovery via the mini USB, but not from the computer — it may interfere with the JTAG pins.

Unload FTDI drivers that could interfere with OpenOCD:

sudo kextunload /System/Library/Extensions/FTDIUSBSerialDriver.kext/

Then run OpenOCD:

cd STM32F4-Discovery_FW_V1.0.1/openocd_config
openocd -f openocd.cfg -f stm32f4x.cfg

Expected output:

Open On-Chip Debugger 0.5.0 (2011-10-30-17:32)
...
Info : JTAG tap: stm32f4xxx.cpu tap/device found: ...
Info : stm32f4xxx.cpu: hardware has 6 breakpoints, 4 watchpoints

One TAP is for the CPU, the other for the FPU.

Programming and Debugging with GDB

In a second terminal:

arm-none-eabi-gdb
(gdb) target extended localhost:3333
(gdb) monitor halt
(gdb) file demo.elf
(gdb) load demo.elf
(gdb) continue
(gdb) br main.c:71
(gdb) info registers

Writing to Flash

So far we’ve only uploaded the code to SRAM. To flash the chip permanently:

arm-none-eabi-gdb
(gdb) target extended localhost:3333
(gdb) monitor halt
(gdb) file demo.elf
(gdb) monitor flash write_image erase demo.hex 0 ihex
(gdb) continue

This works with ST’s demo hex file, but may fail with custom builds due to linker issues.

Currently, it gets stuck in HardFault_Handler() at stm32f4xx_it.c:61. Let me know if you have ideas in the comments.

What Needs Work

  1. Fix the flash writing issue
  2. Add full STM32F4 support to OpenOCD

← Back to blog