pyOCD is an Open Source python 2.7 based library for programming and debugging ARM Cortex-M microcontrollers using CMSIS-DAP. Linux, OSX and Windows are supported.

You can use the following interfaces:

1. From a python interpretor:

• halt, step, resume execution
• read/write memory
• read/write block memory
• read-write core register
• set/remove hardware breakpoints
• flash new binary
• reset

2. From a GDB client, you have all the features provided by gdb:

• load a .elf file
• read/write memory
• read/write core register
• set/remove hardware breakpoints
• high level stepping
• ...

pyOCD relies on external USB libraries:

• Windows: pyWinUSB:

$ cd /path-to-pywinusb/
$ python setup.py install

• Linux: pyUSB:

$ sudo apt-get install python libusb-1.0-0-dev
$ cd /path-to-pyusb/
$ sudo python setup.py install

• Mac: hidapi, cython-hidapi

$ brew install hidapi
$ git clone https://github.com/trezor/cython-hidapi.git
$ cd cython-hidapi
$ sudo python setup.py install

Clone pyOCD somewhere then run the install script.

$ cd /path-to-pyOCD/
$ python setup.py install

Test the installation of pyOCD by running the basic test with an mbed enabled board connected to the computer. The basic_test.py will perform a series of tests on the board and leave it with a blinky program running.

$ python2.7 pyOCD/test/basic_test.py

pyOCD now provide a manual HOW_TO_BUILD.md in root folder to explain how to build pyOCD into single executable gdb server program.

The GDB server works well with Eclipse and the GNU ARM Eclipse OpenOCD plug-in. To view register the Embedded System Register Viewer plugin can be used. These can be installed from inside eclipse using the following links: GNU ARM Eclipse: http://gnuarmeclipse.sourceforge.net/updates Embedded System Register Viewer: http://embsysregview.sourceforge.net/update

The pyOCD gdb server executable will run as a drop in place replacement for OpenOCD. If a supported mbed development board is being debugged the target does not need to be specified, as pyOCD will automatically determine this.
If an external processor is being debugged then "-t [processor]" must be added to the command line. For more information on setup see this post for OpenOCD

A series of tests are provided in the test directory:

• basic_test.py: a simple test that checks:
  • read/write core registers
  • read/write memory
  • stop/resume/step the execution
  • reset the target
  • erase pages
  • flash a binary
• gdb_test.py: launch a gdbserver
• gdb_server.py: an enhanced version of gdbserver which provides the following options:
  • "-p", "--port", help = "Write the port number that GDB server will open"
  • "-b", "--board", help = "Write the board id you want to connect"
  • "-l", "--list", help = "List all the connected board"
  • "-d", "--debug", help = "Set the level of system logging output, the available value for DEBUG_LEVEL: debug, info, warning, error, critical"
  • "-t", "--target", help = "Override target to debug"
  • "-n", "--nobreak", help = "Disable halt at hardfault handler."
  • "-r", "--reset-break", help = "Halt the target when reset."
  • "-s", "--step-int", help = "Allow single stepping to step into interrupts."
  • "-f", "--frequency", help = "SWD clock frequency in Hz."
  • "-o", "--persist", help = "Keep GDB server running even after remote has detached."

from pyOCD.board import MbedBoard

import logging
logging.basicConfig(level=logging.INFO)

board = MbedBoard.chooseBoard()

target = board.target
flash = board.flash
target.resume()
target.halt()

print "pc: 0x%X" % target.readCoreRegister("pc")
    pc: 0xA64

target.step()
print "pc: 0x%X" % target.readCoreRegister("pc")
    pc: 0xA30

target.step()
print "pc: 0x%X" % target.readCoreRegister("pc")
   pc: 0xA32

flash.flashBinary("binaries/l1_lpc1768.bin")
print "pc: 0x%X" % target.readCoreRegister("pc")
   pc: 0x10000000

target.reset()
target.halt()
print "pc: 0x%X" % target.readCoreRegister("pc")
   pc: 0xAAC

board.uninit()

Python:

from pyOCD.gdbserver import GDBServer
from pyOCD.board import MbedBoard

import logging
logging.basicConfig(level=logging.INFO)

board = MbedBoard.chooseBoard()

# start gdbserver
gdb = GDBServer(board, 3333)

gdb server:

arm-none-eabi-gdb basic.elf

<gdb> target remote localhost:3333
<gdb> load
<gdb> continue

An interface does the link between the target and the computer. This module contains basic functionalities to write and read data to and from an interface. You can inherit from Interface and overwrite read(), write(),...

Then declare your interface in INTERFACE (in pyOCD.interface.__init__.py)

A target defines basic functionalities such as step, resume, halt, readMemory,... You can inherit from Target to implement your own methods.

Then declare your target in TARGET (in pyOCD.target.__init__.py)

Defines the transport used to communicate. In particular, you can find CMSIS-DAP. Implements methods such as memWriteAP, memReadAP, writeDP, readDP, ...

You can inherit from Transport and implement your own methods. Then declare your transport in TRANSPORT (in pyOCD.transport.__init__.py)

Contains flash algorithm in order to flash a new binary into the target.

Start a GDB server. The server listens on a specific port. You can then connect a GDB client to it and debug/program the target

Then you can debug a board which is composed by an interface, a target, a transport and a flash