ASRock Rack X570D4U mainboard: pinout

This page describes the undocumented headers and connectors on the ASRock X570D4U mainboard. The official manual for this mainboard describes most other connectors and headers.

BMC debug header

This header labeled BMC_DEBUG1 provides access to the debug serial port of the AST2500 SoC (UART 5). The UART works with 3.3v level signals and provides a 3.3v output and can be found on the bottom left of the mainboard.

Using this port you can access the U-Boot command prompt, the Linux bootlog and a shell.

BMC programming header

This header labeled BMC_PH1 provides access to the MX25L51245G 64MB flash chip containing the BMC firmware. Using an exernal SPI flash programmer this port allows for unbricking and easy reflashing of the BMC firmware during development.

This interface uses 3.3v level signals. Connecting the BMC RESET# pin to GND disables the AST2500, allowing an exernal programmer to reprogram the flash chip without interference from the SoC.

Manufacturing mode header

This header labeled MFG1 is connected to GPIO H4 of the AST2500 SoC. With the official firmware installed shorting this jumper makes the BMC boot into a special debug mode, dropping to a root shell on the BMC_DEBUG1 port. When running OpenBMC this GPIO is available for custom applications.

Chassis identification

These three headers labeled CHASSIS_ID1, CHASSIS_ID2 and CHASSIS_ID3 are connected to GPIO G1, G2 and G3 of the AST2500 SoC for ID1, ID2 and ID3 respectively. On production boards these headers appear to not have been installed, but they are functional. When running OpenBMC these GPIOs are available for custom applications.