Other Parts Discussed in Thread: TPS650250, TPS65216
on a new customer board, UART boot fail, host send Xmodem package upon receive CCC. captured waveform as below, when host send the first package, target AM335x response with NAK
Compare with BBB board wave form, AM335x response ACK after the whole package:
Below is customer's SOM board PCB, route out UART0 TX/RX to the post card board edge directly, there is no serial or pull up/down resistor. use USB to UART TTL cable to connect on the solder point(RED) to capture waveform.
connect with RS232 from base board, same result:
Use logic analyzer to capture the RX signal, the seems add one more bit at each byte.
if use USB to TTL cable, occasionally can boot successfully. the successful waveform captured with logic analyzer as below:
Question:
Tried with several PC as host, same fail result. Any clue to debug this issue?