This is a Whatsminer control board used to control the hashboards via 3 dedicated i2c buses. The PCB has a number of unused IOs that could be repurposed for various hardware interfaces, including JTAG, but probably also USB and possibly even a graphics interface.

Identification

Whatsminer CB4 v10
Manufacturer	W h a t s m i n e r
Dimensions	74mm x 105mm x 1.2mm
Release Date	03 2020
Website	[1]
Specifications
SoC	H6 CV200 OS @ 1.32Ghz
DRAM	256MiB DDR3 @ 672MHz
NAND	256MB?
Power	DC 12V @ ?A, no battery
Features
Network	10/100Mbps Ethernet (rmii
Storage	microSD, nand
Other	4 UART, PSU IO, Hashboard IO, lots of extra unused IOs on the PCB
Headers	UART

The PCB has the following silkscreen on the front:

CB4_V10
20200303

Sunxi support

This is very much work in progress at this point.

Current status

No support yet in sunxi.

Manual build

The hello world from sunxi-tools works. The Orangepi 3 u-boot partly works, but fails to initialize the RAm and displays an message to that effect. With changes to the RAM settings it is possible to reach a u-boot shell with still some limited hardware support (no nand or ethernet).

FEL mode

It is possible to enter FEL mode by pressing the 2 key during the BOOT0 sequence, but due to the lack of an available USB port this is not useful, nor is it necessary as it is possible to boot directly from SD card anyway.

Locating the UART

The board breaks out a 4-pin header, labelled VCC, RX, GND, TX - do not connect the VCC header. This can be used with a Serial 3.3V TTL adapter at 115,200bps 8N1 to monitor the boot process. Except for the FEL interrupt, there is seemingly no other interaction possible from WhatsMiner-SDCard-Burn-Image-h6os-20220422.18.img firmware versions.

Pictures

Front of the PCB
Back of the PCB

Whatsminer CB4 v10

Contents