Yesterday, I talked about looking for a console port on the Bell ExpressVu 9200 (aka Dish 942) receiver. After completely disassembling the unit, I discovered a 5-pin pad on the motherboard labelled ‘UART’ located underneath the power supply. Interesting! I soldered a header plug and brought the cable outside the chassis.

The pin assignment appears to be as follows:

• 1. +3.3v
• 2. RxD
• 3. TxD
• 4. ???
• 5. GND

Looking at TxD with a scope shows that it starts at 0v, and after avout 3 seconds jumps up to 3.3v. It stays at 3.3v and doesn’t appear to change at all. I hooked up a MX3232 (3.3v version of a MAX232) to convert the signals to RS232 levels.

Unfortunately, I’ve been unable to coax the serial port to life. I tried sending carriage returns at different baud rates. I’ve still got to try sending a break signal. Also, pin 4 might be some sort of CTS signal that might need to be asserted. Still lots to try!