Serial Console Access on B3

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Author: PA

Gaining access to the serial console on B3 is neccessary if you would like to access u-boot to modify any boot parameters or to gain access without a working network.

B3 has the a serial port onboard, but is normally used only for test purposes. The serial port is 3.3V logic, so to connect it to a regular PC port the RS232 drivers would be needed outside B3.

However, FTDI has a USB->3.3V-TTL cable that can be used (TTL-232RG-VREG3V3-WE), it can be bought at various places, one is

On this cable the following should be connected to B3:

Orange cable (PC TX data) -> UART0_RX, testpoint 65

Yellow cable (PC RX data) -> UART0_TX, testpoint 66

Black cable -> GND, Connect to one unused PCIe latch pad

See file for description of solder points.

Serial solderpoints.JPG

In short the following needs to be done:

  • Extract the main board from the aluminum casing
  • Solder the three wires as described above
  • Connect the USB cable to your PC
  • Open your favorite serial communication program (e.g. PuTTY)
  • Find out what your system called the USB cable (e.g., COM1, /dev/ttyUSB0)
  • Set the speed/baud rate to 115200.
  • Connect!