By EZ in Releases — Jun 22, 2024

BitAxe Supra: 4th Major Revision with BM1368 ASIC from Antminer S21

bitaxe is a fully open source hardware Bitcoin ASIC miner. Supra is the 4th major revision of the bitaxe that now includes the BM1368 ASIC from the Antminer S21.

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"The newest member of the #bitaxe lineup, the bitaxeSupra is working! Single BM1368 ASIC (from the Antminer S21) running around 620 GH/s. Open source everything. Another huge effort from the Open Source Miners United crew on figuring this one out," announced skot9000 back in February.

"The bitaxe Supra (401) design is ready for release. Look for the branch if you want to dig in now. The git repo is a total mess right now, so I’m in the process of reorganizing it. Stay tuned," skot said on March 24.

Join Open Source Miners United group on Discord to learn more.

BM1368

The BM1368 is a undocumented SHA256 mining ASIC from Bitmain. It's used in the Antminer S21.
Bitmain claims the BM1368 has 17.5 J/TH efficiency.
The BM1368 is brand new and isn't available anywhere yet.
The BM1368 has a different footprint and pinout from the BM1366, BM1397 and BM1387 in previous bitaxe.

Key features

ESP32-S3-WROOM-1 wifi microcontroller on board.
TI TPS40305 buck regulator steps down the 5V input to power the BM1366.
Maxim DS4432U+ current DAC digitally adjusts the BM1368 core voltage from 0.04V to 2.4V.
TI INA260 power meter measures the input voltage and current of the miner.
Microchip EMC2101 PWM controls the fan and monitors tach output. BM1366 doesn't support die temp, but we have it placed super close to the ASIC so we can use the internal temp feature.
0.91" SSD1306 OLED I2C Display Module.

Hardware

Order PCBs from your favorite PCB shop, like JLCPCB, SeeedStudio, or PCBWay
- Gerbers are in the Manufacturing Files dir. PCBs are 4-layer, 6mil trace/space and 0.3mm hole compatible. 1oz outer / 0.5oz inner layer thickness works well.
- Make sure to order stencils too. These are the "paste" layers in the gerbers folder. one for top and one for bottom.
All PCB parts except the ASIC are available from DigiKey and others. You can find Digikey part numbers on the DK tab of the BOM
40x40mm heatsink and 5V fan from a random AliExpress seller. The fans are crap, but the heatsinks are good. make sure to use a good quality thermal compound between the heatsink and ASIC!
Upgrade your fan with the Noctua NF-A4x10 5V 4-Pin fan for a much more pleasant experience.
Supports 0.91" SSD1306-based I2C OLED Module. Example Amazon seller
KiCad 7 design files.