AstroUniBoard

A custom STM32G0B1-based telescope controller board focused on focuser and rotator control. Firmware is a port of OnStepX to a custom PCB, with added SHT31 weather sensor support and DFU bootloader management.

Repository Structure

AstroUniBoard/
├── FW/                     # Firmware (PlatformIO / Arduino / OnStepX)
│   ├── src/                # OnStepX source tree + custom config
│   ├── platformio.ini      # Build configuration
│   └── tools/              # Firmware manager MCP server (DFU upload)
├── HW/                     # Hardware (PCB designs, schematics — KiCad)
└── docs/
    ├── HARDWARE.md         # Pin assignments and hardware overview
    └── FIRMWARE.md         # Build and upload guide

Hardware

MCU	STM32G0B1CBT6 (ARM Cortex-M0+ @ 64 MHz)
Flash / RAM	128 KB / 144 KB SRAM
Package	48-pin LQFP
Stepper Drivers	2× TMC2209 (UART, shared bus)
NV Storage	24AA64 I2C EEPROM (8 KB)
Weather Sensor	SHT31 (temperature + humidity, I2C)
Interface	USB CDC (native USB PA11/PA12)
Upload	DFU bootloader (ROM)

Axes

Axis	Function	Driver	UART Address
AXIS3	Rotator	TMC2209	1
AXIS4	Focuser	TMC2209	0

Mount axes (AXIS1/AXIS2) are disabled — this board is focuser/rotator only.

See docs/HARDWARE.md for full pin assignments.

Firmware

Based on OnStepX — advanced telescope controller firmware with LX200 protocol compatibility, ASCOM support, and stepper motor control.

Custom additions in this port

• STM32G0B1.h — HAL implementation for STM32G0B1CBT6
• Pins.AUB_FocRot.h — Custom pinmap (model AUB_FOCROT = 25)
• SHT31 weather sensor support (not in upstream OnStepX)
• :EDFU# command — jump to DFU ROM bootloader for firmware updates
• Activity LED (PB4) driven by focuser/rotator movement

Build status

• Flash: 93.3% (122,244 / 131,072 bytes)
• RAM: 8.2%
• Compiler: ARM GCC, -Os -std=gnu++17
• Hardware tested and functional

Quick start

1. Install PlatformIO
2. Open the FW/ folder in VS Code
3. Build: Ctrl+Alt+B (environment: nucleo_g0b1re)
4. First upload: put board in DFU via BOOT0 switch, then Ctrl+Alt+U
5. Subsequent uploads: send :EDFU# via serial to enter DFU, then upload

See docs/FIRMWARE.md for full build and upload instructions.

Serial Commands

Command	Action
:EDFU#	Jump to DFU ROM bootloader (firmware upload)
:ERESET#	Reset MCU
:ENVRESET#	Wipe NV memory (takes effect on next boot)

Plus the full OnStepX LX200 command set.

Communication

• Port: USB CDC (virtual COM port, no driver needed on Linux/Mac; WinUSB on Windows)
• Baud rate: 115200
• Protocol: LX200 / OnStepX command set
• Compatible clients: ASCOM OnStep driver, INDI OnStep driver, Android OnStep apps, Sky Planetarium

Tools

Firmware Manager MCP Server

FW/tools/firmware_manager/server.py — MCP server that automates DFU firmware updates from Claude Code or any MCP client.

pip install -r FW/tools/firmware_manager/requirements.txt
python FW/tools/firmware_manager/server.py

Key tool: enter_dfu_and_upload(port, firmware_path) — sends :EDFU#, waits for re-enumeration, uploads via dfu-util.

License

Firmware is licensed under the GPL (inherited from OnStepX). See FW/src/LICENSE.

Credits

• OnStepX firmware by Howard Dutton and contributors
• STM32G0B1 HAL port and AstroUniBoard hardware by the project author