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Ser2usb stops when attached to PC


#1

I have the Fez Panda II Ultimate Kit. I’ve hooked up the Connect Shield and the Ser2USB E-Block. I’m running off USB.

My program is a simple loop that is writing the current time out the serial port.

If I don’t have the PC attached to the USB port on the Ser2USB E-Block the Tx led blinks brightly (strangely the Rx led blinks faintly at the same time, despite there being no Rx data).

I’ve verified the signal is getting to the E-Block okay and appears to be valid serial data.

When I hook up the PC, the E-Block is recognized and a serial port is created. But simultaneously the E-Block’s LED quit blinking. The signal is still getting to it but nothing seems to happen.

Have I overlooked some hardware configuration? Does the fact the Rx light faintly blinks in unison indicate a hardware failure of some kind?


#2

Addendum: When I pause execution via the debugger the Rx and Tx leds still blink on the Ser2USB E-Block (provided the PC is not attached). Maybe they’re signaling some state.


#3

Put a wire from TX to RX on the eblock, open a terminal software and see if date you type get echoed back. Now remove the wire and verify that thy are not.


#4

Is the problem with the way the led blinks or with the data not being received at the PC?


#5

Well I fell into the classic failure of serial communication. I had the Rx/Tx wrong.

I was expecting the Rx / Tx swap to happen after the E-Block, not before. Once I swapped the connectors at the Fez Connect board the time stamps were being visible in the PC’s hyperterminal.

Thanks for your quick attention.