STM32Fxxx micro-controller hacking in Haskell

STM32-Zombie

The STM32-Zombie library turns a STM32 microcontroller into a powerful Haskell-hackable hardware interface. It gives the user full control of the STM32Fxxx hardware peripherals without the need to write any c-code, without cross-compiler tool chain and even without any particular microcontroller firmware. The library is called STM-32 Zombie because it halts the brain, i.e. the ARM CPU of the controller board and instead uses the on-cip-debugging features of the controller. The boards run like a Zombie without using its own brain.

Compatible Hardware

I have tested the library with the following hardware:

• ST-Link USB dongle (Google for "ST-Link V2 stlink mini STM8STM32 STLINK simulator")

• A STM32F103 breakout board (Google for " "STM32F103C8T6 ARM STM32 Minimum System Development Board Module")

The USB dongle as well as the breakout boards are available in China starting at about US$2. The cheap ST-link clones and the breakout boards work well but the US$2 ST-Link clones provide no electrical isolation to protect your PC or Laptop. Experimenting with Hardware is a lot of fun until you let the magic smoke out. A ST-LINK/V2-ISOL programmer, that guaranties electrical isolation and full protection of the PC, is very affordable and may be a good investing.

How it Works

One end of ST-Link dongle plugs into the PC USB port the other end is the so called SWD (single wire debug) interface. The SWD interface, which also provides electrical power, is connected to the STM32F103 breakout with 4 jumper wires. As most breakout boards come with a LED, this is all that is needed to run the App.Blink example. Via the SWD interface the PC can read and write the controller CPU address space and access the memory-mapped hardware registers.

API

The STM32-Zombie library is modeled after the STMicroelectronics STM32F10x firmware library which provides a low level interface to the controller hardware. This API is suitable for bare metal hardware hacking but also allows to build higher level interfaces.

Examples and features

The STM32Fxxx controllers feature a wide variety of powerful and flexible hardware peripherals like GPIO port, serial, SPI, I2C interfaces and 12bit-ADC converters and USB ports. The killer feature is, that they also include a flexible DMA controller that can be uses in combination with the peripherals. This makes it possible to build hard-real-time applications that work completely independent from the controller CPU. Examples are ADC sampling and high sampling rate and with precise timing, high frequency sampling of digital inputs or generation of high frequency digital output patterns.

The library does not cover all of the STM32 hardware. I add support for something when I need it in a particular project. (For example I have not tried the USB features of the boards, which seems to be very interesting project)

The examples are in the App module hierarchy.

App.Blink

Blink a LED.

App.ADC

Buffered ADC converters with DMA transfer.

App.DMABuffer

An example for a serial ports with DMA transfer.

App.TestLCD

An LCD driver. This is the original code from the hArduino library with some very small adaptions.

App.WS1228B

A driver for nice colorful RGB LED strips. (Uses SPI and DMA)

App.Serial

Hello world example for serial ports.

Todo

Packages

STM32-Zombie

STLinkUSB

The STLinkUSB package contains a Haskell driver for ST-Link USB dongles. The library is based on information from the openocd library. The STM32-Zombie package only uses a small subset of the ST-Link features and only these features of ST-Link protocol are really tested and included in STLinkUSB. (There is some extra but untested code).

STM32F103xx-SVD

This package contains names and definitions for STM32F103 peripherals, registers, addresses and the bits of the hardware registers. It is generated from STM32F103xx.svd.

SVD2HS

The compiler that translates a file called STM32F103xx.svd to a set of Haskell data types and lookup tables.