??? 02/25/05 10:54 Read: times |
#88436 - Check Responding to: ???'s previous message |
Steve M. Taylor said:
I have seen so many people assume that the serial port MUST be working. TEST it with an oscilloscope. Evem without a scope, loop-back tests can give you a high degree of confidence: 1. Put a loopback connector on the PC's COM port. If this doesn't work, you obviously have a PC problem. If this works, you know that all the PC's transmit and receive hardware & software is working, but it could still have baud-rate or framing errors, or other problems that allow it to talk to itself but nothing else. 2. Short-circuit the UART Rx and Tx pins at the microcontroller (you will need to isolate the processor's Tx pin). Connect to the PC - characters sent by the PC should be looped back to the PC. If this doesn't work, you have a problem with the cable, or something on your target board. If this works, you know that all your target's transmit and receive hardware is also working up to the processor pins, but the PC could still have baud-rate or framing errors, etc, or there could be a problem in your software and/or the microcontroller. |
Topic | Author | Date |
UART doesn't work in XP HyperTerminal? | 01/01/70 00:00 | |
Settings ? | 01/01/70 00:00 | |
It has Identical settings on XP | 01/01/70 00:00 | |
Turn Off handshaking | 01/01/70 00:00 | |
Port com does function fine | 01/01/70 00:00 | |
What LED? | 01/01/70 00:00 | |
Com port | 01/01/70 00:00 | |
are you? | 01/01/70 00:00 | |
The max232 is not needed????? | 01/01/70 00:00 | |
It *is* needed! | 01/01/70 00:00 | |
Mainboard's com is right | 01/01/70 00:00 | |
loopback | 01/01/70 00:00 | |
Check | 01/01/70 00:00 | |
Check | 01/01/70 00:00 | |
Sure | 01/01/70 00:00 | |
but | 01/01/70 00:00 | |
I already probed the port, cable 0.5mts | 01/01/70 00:00 | |
Don't guess | 01/01/70 00:00 | |
too much confidence | 01/01/70 00:00 | |
Waaaaaaaaay too much confidence !! | 01/01/70 00:00 | |
it would be some drivers missing | 01/01/70 00:00 | |
Some Drivers Really Missing | 01/01/70 00:00 | |
XP | 01/01/70 00:00 | |
Do the loopback! | 01/01/70 00:00 | |
Try one more. | 01/01/70 00:00 | |
Really??![]() | 01/01/70 00:00 |