The bitaxe

an experimental BM1387 bitcoin mining machine

BM1387

• The BM1387 is a undocumented SHA256 mining ASIC from Bitmain. It's mostly used in the Antminer S9
• Bitmain claims the BM1387 has 0.098j/Gh efficiency
• The BM1387 is available for around $1-2 each in low quantities from Aliexpress

Current Status

• I have built 2 of these.
• I can't get any response from the BM1387s yet.
• The current comsumption does change like I would exprect when I send a serial command to change the frequency.

Hardware

• BM1387B from random AliExpress seller. Do these work?? Who knows!
• 40x40mm heatsink and 5V fan from a random AliExpress seller. At least half of these arrived broken in some way. But they are cheap and the working ones do keep the BM1387's nice and cool when used with some thermal compound.

Software

Check my BM1387 Scripts!

Connections

Pin Name	Description
VIN	ASIC VIN - powers both ASICs in series. should be around 1.6V
+5V	5V input gets regulated to 1.8V and 0.8V for the BM1387. Also 5V for Fan output
+5V (Fan)	5V output for fan
SPD (Fan)	Speed input from fan. Doesn't currently go anywhere
1V8	1.8V output. regulated from 5V. Use as a IO reference
RXI	1.8V Serial input
TXO	1.8V Serial output
RST	Inverted reset pin to the first BM1387. Unsure what to use this for.
GND	Common ground