Serial Console Access on B3
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 mouser.com:
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.
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.