Open Source Bitcoin Miner - MakerAxe Lite!

MakerAxe-Lite was born out of my curiosity for exploring the world of cryptocurrency and reverse engineering. MakerAxe-lite is the first attempt to extract the essentials of OSMU Bitaxe (Open Source Miners United), reduce it to the minimum, and create a foundation for building new and exciting hardware in the future.

Github repository

1. Get the gerber file of the v0.35 for the pcb.
2. Send them to a PCB manufacturer (Our sponsor is PCBWAY)
3. You can read the schematics for the pcb.
4. You can download the latest version from the BitAxe repository.
5. The interactive BOM files with all the components can be found on the repo.

Remember that even if the project is published, new hardware&software can be deployed, so stay always with stable (or released) branches of the repository.

Here we have two different parts. The first one is the CH224K used to negotiate over USB a valid voltage. 20V, 15V, 9V and 5V are elegible voltages, depending on the CFG2, CFG3 and CFG1 pins. 9V voltage is selected on the schematic shown, but with some test we saw that the more reliable and stable was de 5V option.

In adition to that, we need to ensure a 5V rail not only for other electronics but for the fan as well. Having that, IC U3 is a linear regulator that provide with the needed voltage rail.

Here we can divide into three different sections:

1. The primary circuit is the TPS40305, which is controlled over the Feedback Pin. The coil is prepared to work with voltages up to 20V, but is not as efficient as possible with 9V or 5V.
2. The second part is the U5 or DS4432, which is a DC Sink/Source supply that are controlled over I2C from the main microcontroller. This gives us the ability to alter the voltage to the ASIC, which will require between 1 and 1.5V, depending of the overclock is activated.
3. Last but not least, the INA260 is the IC that monitores the current draw and power consumption of the ASIC.

The primary controller is a ESP43-S3-WROOM with at least 16Mb flash memory. The S3 has WiFi capabilities which are essential to connect with the pool and get the blocks to mine. It also controls the voltage of the asic, and all the communication with the ASIC. It also has a USB connection for debugging with a computer. It has a RT9080 power supply that converts the 5V rail into a 3.3V rail for the controller.

The BM1366 is the main IC. It is an ASIC which was developed to mine SHA256 algorithms. It needs a level shifter so the ESP32 (3.3V) can communicate with the ASIC (max 1.8V). For this purpose, we need to add two more DC/DC converters. In this case, we are creating a 0.8V and a 1.8V voltage levels.

The main chip for the cooling system is the EMC2101. This chip let us set a specific speed for the fans. In addition, it allow us to read the rpms of the fan.

For the PCB, a "Y" cable is choosen since we assembled the pcb with two fans. One over the ASIC (and some thermal paste), and another on the back, pointing at the buck converter. The second one is not mandatory, but recommended so all the electronics works flawlessly.

We designed everything to fit a two layer PCB. The problem with that is thermal management becomes a huge problem. You can see the attached pictures:

1. The overall PCB with all the components.
2. The voltage path from the 20V input to the 1.2V ASIC Supply
3. The ASIC layout.
4. ESP32 Layout

We strongly recommend that you solder the bottom part first, then the top layer. An oven can be used, but in our case we have used the PCBA service from PCBWAY.

The most sensible component is the BM1366 itself, so we advice to only order the gerbers and components if you have severe experience with soldering.

Last but not least, the TH components should be prepared afterwards.

I highly recommend to use the official espressif software serial flasher. You can click "connect" at 921600 baudrate. If everything is OK, you will see how the flasher connects to the microcontroller and you will see some data from the chip. At this moment, you need to load to the 0x0000 space the official bitaxe software. You need to select "esp-miner-factory-205.bin" (Choose the latest SW released)

A data scraper was developed in Python to collect all available information about the Makeraxe PCBs and to evaluate their long-term reliability. As shown in some of the images, the power consumption is approximately 11W, and the hashrate is around 500 GH/s. These units have been running 24 hours a day for several months, which allows us to conclude that they have proven to be successful.

First of all, if you like my projects, I strongly recommend you to follow us on our Instagram profile, Where you will be updated on a weekly basis.

In addition, you have my tree-link website to check all my social media and website!

https://makingdevices.com/links/

If you want to support Making Devices, there is also a YT channel that we are hoping to start very soon.

Finally, I would like to thank PCBWAY, the sponsor of this project. I really recommend you pay them a visit if you are thinking of ordering some Gerbers at any time in the future. I am truly impressed with how good they work and the high quality of their PCBs.