stm32f4discovery

stm32f4discovery: Platform-Specific Instructions

(http://www.st.com/en/evaluation-tools/stm32f4discovery.html)

Flashing the kernel

To program the Tock kernel onto the Discovery, cd into the boards/stm32f4discovery directory and run:

make flash-debug

This will build boards/stm32f4discovery/target/thumbv7em-none-eabi/debug/stm32f4discovery and use openocd to flash it to the board.

Apps

All user-level code lives in the userland subdirectory. This includes a specially compiled version of newlib, a user-level library for talking to the kernel and specific drivers and a variety of example applications.

To compile an app, cd to the desired app and make. For example:

cd tock/userland/examples/c_hello/
make TOCK_BOARD=stm32f4discovery

Flashing one app

cd tock/userland/examples/c_hello/
make TOCK_BOARD=stm32f4discovery flash

Flashing multiple apps

cd userland

APPS="buttons c_hello"
BINS=()

for APP in $APPS; do
  pushd .
  cd "../../tock/userland/examples/${APP}/"
  make TOCK_BOARD=stm32f4discovery
  popd
  BINS+=("../../tock/userland/examples/${APP}/build/cortex-m4/cortex-m4.bin")
done

APP_BASE_ADDR=0x08080000 ./tools/flash/stm32f4.sh "${BINS[@]}"

Debugging using Visual Studio Code

TODO (Status: working very well)

Edit discovery.code-workspace and point rust.sysroot to correct full path to .xargo in this directory.

Console I/O

The the kernel debugging console and the stdout console is implemented using semihosting.

Huge benefit of semihosting console is that it in contrast to UART console requires no hardware initialization.

std_out_init() initializes the semihosting only if a debugger is connected so the kernel can run without debugger out-of-box without needing to replace or remove the semihosting console in code.

To enable semihosting with one needs to add arm semihosting enable to openocd initialization commnds e.g.:

openocd -f interface/stlink-v2.cfg -f target/stm32f4x.cfg -c "init; reset halt; arm semihosting enable"

The command can also be passed from gdb using monitor arm semihosting enable command.