Maven/wAVR WiFi and USB Debug Probe Firmware
The Maven Programmer/Debugger is a small WiFi-enabled in-system programming and debugging device for ARM Cortex-M micro-controllers originally designed by Maverick Embedded Technology Ltd. In early 2022, the decision was made to Open-Source the firmware for the device. The hardware design(s) will also released in due course.
Numerous significant features set Maven apart from other ARM programmers/debuggers:
- Built-in GDB server accessible over USB or WiFi means Maven works with any host system which can run GDB for ARM.
- Does not require middleware running on the host, such as OpenOCD, and the associated configuration file(s).
- Supports Cortex-M TRACESWO serial data in NRZ mode at up to 3MHz.
- Communicates with your target using RS232 on a UART or bit-banged I/O pin. Maven will make the UART data available over WiFi using the telnet command on your host. Both RxD and TxD are supported at all the common baud rates.
- Maven firmware supports an OLED display to keep you informed of both its status and various target parameters.
- The optional USB interface provides CDC-compatible RS232 interfaces. One of those is dedicated to TRACVESWO data. Another other provides access to the same target UART interface mentioned above. Note: the number of CDC interfaces is hardware-dependent.
Maven’s primary purpose is to act as a GDB server on behalf of the target micro-controller. In this role, the Gnu Debugger (GDB), or IDE supporting the GDB remote protocol, running on a host computer can control and inspect the state of the target’s CPU core and its connected peripherals using the GDB ‘extended-remote’ target protocol. Maven translates instructions received from the debugger into the appropriate register and memory read/write requests over the ARM CPU’s ADIv5 interface known as the Serial Wire Debug Port (SWD-DP).
Maven supports breakpoints both in RAM and in Flash memory. The latter utilising Cortex-M hardware breakpoints where available - most Cortex-M cores have around 6 hardware breakpoints. Maven supports up to 128 software breakpoints for code running in RAM. In most cases GDB will choose the appropriate type of breakpoint automatically, since Maven informs GDB of the address/size/type of memory regions for supported targets.
Hardware watchpoints are also supported, where available on the target Cortex-M core. These can be used to halt execution when firmware accesses specific memory addresses, and are an invaluable tool to help track down memory corruption and/or use-after-free type bugs.
You'll need the ARM toolchain together with a reasonably recent version of Gnu make to build the Maven firmware.
You'll also need to build tools/makefsdata if you update the html source
in src/network/http/html.
Makefiles are provided to build Maven firmware for a number of targets and configurations. For example:
$ cd build/wAVR/cortexm
$ make
The above will create a debug firmware image for the original wAVR/Maven hardware. Alternatively:
$ cd build/MCULink/cortexm
$ make
The above will create a debug firmware image for the NXP MCULink debug probe.
Note that the author's development environment is MacOS. Your mileage may vary when building on another platform.
The MCU-Link hardware from NXP is a small USB debug probe whose firmware implements the usual CMSIS-DAP protocol. This is probably the best device with which to start playing with Maven firmware as it is very easy to replace its default firmware image.
See build/MCULink/README.txt for information on how to replace the stock
firmware with Maven.
Maven started life as a WiFi programmer for AVR devices, working in
conjunction with avrdude. This
version of the firmware can be built using the Makefiles in build/wAVR/avr
and build/Maven3/avr.