BitForge Nano

🪙 Open Source Bitcoin Miner PCB – CERN OHL 2 - S Licensed

This project presents a fully open-source Bitcoin mining hardware platform, designed for transparency, modularity, and extensibility. Built around the BM1370 ASICs and powered by an ESP32-S3 microcontroller, this board offers a compact yet powerful solution for enthusiasts and developers interested in cryptocurrency mining hardware.

Released under the CERN OHL 2 S, all design files, firmware, and documentation are freely available for use, modification, and redistribution.

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📌 Key Features

• Open Source Hardware & Firmware – CERN-OHL-S licensed
• Dual BM1370 ASICs for parallel mining
• ESP32-S3 as the central controller
• Precision power monitoring via INA260
• Multi-stage voltage regulation from 12 V down to 0.8 V
• UART communication with level shifting
• Temperature monitoring & fan control per ASIC
• USB-C interface for firmware upload and updates
• Status LEDs for visual feedback
• Modular I2C architecture with multiplexer support

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🔧 Technical Overview

Power Architecture

The board is powered via a 12 V barrel jack, with a recommended power supply of at least 70 W to ensure stable operation under full load. Power distribution is carefully managed through multiple buck converters:

• TPS546A24 Buck Converter: Converts 12 V to 1.2 V, configurable via SMBus/I2C
• 12 V → 5 V Buck Converter
• 5 V → 3.3 V Buck Converter
• From 3.3 V, two reference voltages (1.2 V and 0.8 V) are derived for the ASICs

A Texas Instruments INA260 is used to monitor the total current and voltage, providing accurate power consumption data for the entire board and its peripherals.

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ASICs & Communication

The core mining functionality is handled by two BM1370 ASICs, connected in parallel and powered by the regulated 1.2 V supply. These chips communicate via UART, with signal levels adjusted using a SN74AVC level shifter to ensure compatibility between the ESP32-S3 and the ASICs.

Each ASIC requires two reference voltages (1.2 V and 0.8 V), which are derived from the 3.3 V rail using dedicated regulators.

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Thermal Management & Fan Control

Each BM1370 ASIC includes an internal die temperature sensor, which is monitored by an EMC2101 temperature controller. These controllers also support PWM fan control, allowing each ASIC to drive a dedicated 12 V cooling fan.

Since the EMC2101 has a fixed I2C address, a PCA9544 I2C multiplexer is used to switch between the two devices, enabling independent monitoring and control.

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Control & Interfaces

At the heart of the board is an ESP32-S3, which runs the firmware responsible for:

• ASIC initialization and control
• Power and temperature monitoring
• Fan speed regulation
• Communication via UART and I2C
• Status indication via two onboard LEDs

A USB-C port is provided for firmware flashing and future updates, making development and deployment straightforward.

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🛠️ Open Source & Licensing

This project is proudly released under the CERN Open Hardware Licence Version 2 - Strongly Reciprocal (CERN-OHL-S). This means:

• You are free to use, study, modify, and distribute the hardware designs
• Any derivative work must also be released under CERN-OHL-S
• If you manufacture or distribute products based on this design, you must provide recipients with access to the complete source files
• Contributions and improvements are welcome!

The CERN-OHL-S is specifically designed for open-source hardware, ensuring that designs remain open and accessible. We believe in open collaboration and transparency, and by releasing this project under CERN-OHL-S, we aim to foster innovation in the hardware mining community and provide a solid foundation for further development.

For the full license text, see the LICENSE file.

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