STM32Miner

Overview

STM32Miner is a project for making a Bitcoin mining board consisted of microcontrollers. A board consists of a master, which receives work from an external source, then splits it into multiple jobs which will then be sent to worker MCUs.

This is the source code of the firmware running on the worker MCUs.

Why?

I figure out this is the best way to get started with programming on the STM32 and ARM Cortex-M uC.

Compatibility

Currently, this firmware is only knows to work on the STM32F030F4P6.

The firmware contains platform-dependant stuff like RCC, UART, I2C which is not compatible with other STM32 and ARM Cortex-M parts. It might be compatible with the STM32F2/3/4 line, but definitely not the STM32F1/not STM32 line.

Building and installing

Flavours

You can either make a debug build or a production build:

• Production build: Fat (uses nearly all the available Flash space), fast (nearly 6khash/s), doesn't print any debug messages over UART. Recommended.
• Debug build: Small (about 8k), slow (as SHA-256 loops are not unrolled), prints a lot of debug messages over UART at 921600 baud.

Building

Prerequisite:

• General stuff: make, git, python
• ARM specific: arm-none-eabi-gcc, arm-none-eabi-binutils, arm-none-eabi-newlib
• STM32 specific: stlink

On Arch Linux, use the following command to install them:

pacman -S make git arm-none-eabi-gcc arm-none-eabi-binutils arm-none-eabi-newlib python stlink

Then clone this repository and initialize its submodules:

git clone https://gitlab.com/tuankiet65/stm32miner
cd stm32miner
git submodule init
git submodule update

Then build it:

make lib
make PRODUCTION=1 all # if production build
make PRODUCTION=0 all # if debug build

Installing

Connect your STM32F030F4P6 to your computer via a ST-Link v2 programmer, then run:

make upload

to upload the firmware to the microcontrollers.

Usage

All communication with the master is done using I2C:

• PA9: SCL
• PA10: SDA

The firmware exposes itself as a register bank with the following structure:

Address	Name	Size (in bytes)	Type	Description	RW/RO
0x00	version	8	char[8]	Firmware's git commit	RO
0x08	state	1	uint8_t	Current state of the miner	RO
0x09	hashrate	4	uint32_t	Current hashrate	RO
0x0d	current_job_id	1	uint8_t	Job ID of the current job`	RO
0x0e	winning_nonce	4	uint32_t	Current hashrate	RO
0x12	new_job_id	1	uint8_t	New job ID	RW
0x13	new_header	80	uint32_t[20]	New block header	RW
0x63	execute_job	1	uint8_t	Write non-zero value to mine the new block header	RW

state is defined as:

#define STATE_READY 0x01
#define STATE_WORKING 0x02
#define STATE_FOUND 0x03
#define STATE_NOT_FOUND 0x04
#define STATE_ERROR 0xff

To initiate a mining job:

• Write the job ID to new_job_id
• Write the 80-byte header to new_header
• Write any non-zero value to execute_job. The firmware will start mining the new block header immediately. When it starts the current_job_id will change to the ID of the started job.

To retrieve the result of a mining job:

• Poll finished until it contains a non-zero value
• Fetch the nonce in winning_nonce. This is the nonce that causes the block's SHA256d hash to contain at least 32 leading zeros (aka the leading 4 bytes are 0x00000000)