Using OpenOCD

Using OpenOCD#

To program your microcontroller using OpenOCD, use the following command:

openocd -f interface/cmsis-dap.cfg -f target/rp2040.cfg \
        -c "init" -c "reset init" \
        -c "flash write_image erase blink.bin 0x10000000" \
        -c "reset run" -c "shutdown"

Supported Microcontrollers#

This guide supports the following microcontrollers:

Microcontroller

Description

RP2040

Low-cost microcontroller with a dual-core ARM Cortex-M0+ processor.

STM32F103C8T6

Budget-friendly microcontroller with an ARM Cortex-M3 processor.

STM32F411

Cost-effective microcontroller with an ARM Cortex-M4 processor.

Selecting Your Microcontroller Target#

Each microcontroller requires a specific configuration file. This file is a script that instructs OpenOCD on how to communicate with the microcontroller. The configuration file is tailored to the microcontroller and the debugger interface.

Microcontroller

Configuration File

RP2040

rp2040.cfg

STM32F103C8T6

stm32f103c8t6.cfg

STM32F411

stm32f411.cfg

PyOCD#

PyOCD is a command-line tool for interacting with ARM Cortex-M microcontrollers. It supports flashing, erasing, debugging, and low-level memory access using CMSIS-DAP, DAPLink, ST-Link, and other probes.

Basic Syntax#

pyocd <command> [OPTIONS]

You can specify the target using -t <target> or through a configuration file using --config <file.yaml>.

Configuration File#

Use a YAML configuration file to define global options:

# Misc/pyocd.yaml
target_override: py32f003x6
frequency: 1000000
log_level: info

To load this config:

pyocd erase --config ./Misc/pyocd.yaml

Commands#

Erase flash memory of the target device.

pyocd erase -t py32f003x6 [OPTIONS]

Options:

  • --chip: Erase the entire flash memory.

  • --sector <ADDR>: Erase a single sector by address.

  • --config <file.yaml>: Load configuration from YAML file.

Example:

pyocd erase -t py32f003x6 --chip --config ./Misc/pyocd.yaml

Flash a binary, hex, or ELF file to the target.

pyocd flash <file> -t py32f003x6 [OPTIONS]

Options:

  • --base-address <addr>: Override the base address (for .bin files).

  • --verify: Verify flash contents after writing.

  • --erase=chip|sector|auto: Select erase mode.

  • --format bin|hex|elf: Force file format.

  • --config <file.yaml>: Load YAML config.

Example:

pyocd flash firmware.hex -t py32f003x6 --erase=chip --verify

Start a GDB server for remote debugging.

pyocd gdbserver -t py32f003x6 [OPTIONS]

Options:

  • --port <number>: GDB server port.

  • --telnet-port <number>: Telnet monitor port.

  • --persist: Keep the server alive after GDB disconnects.

  • --config <file.yaml>: Load YAML config.

Reset the target microcontroller.

pyocd reset -t py32f003x6 [OPTIONS]

Options:

  • --halt: Halt the CPU after reset.

  • --config <file.yaml>: Load YAML config.

List connected debug probes and supported targets.

pyocd list

Read and write memory directly.

pyocd read32 0x08000000 4
pyocd write32 0x20000000 0x12345678

CMSIS-Pack Targets#

To add custom target support (e.g., py32f003x6), use:

pyocd pack install py32f003x6

Or add a local .pdsc file:

pyocd pack add ./path/to/PY32F003.pdsc

Example Workflow#

pyocd list
pyocd erase -t py32f003x6 --chip
pyocd flash build/main.hex -t py32f003x6 --verify
pyocd gdbserver -t py32f003x6
pyocd reset -t py32f003x6 --halt

References#

Command Help#

pyocd --help
pyocd flash --help
pyocd erase --help
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