I have a board where I was, till I discovered the issue, injecting 5v to the
UARTs of the MSP (newbie oversight, I know). The electrical issue has been
corrected (with MAX3232 for one UART and resistive divider for Rx of the other,
Tx not used).
Code downloads and runs on the MSP and UART1 functions correctly.
- BUT -
It seems that data being sent from UART1 is being *received* at UART0. There is
no electrical fault on the board.
My question:
Could the previous applications of 5v to the UARTs (both) have caused some
internal issue that can cause this crosstalk yet MSP seems to be working
correctly in all other respects?
Thanks
Crosstalk between UART0 and UART1 - it is possible?
Started by ●April 3, 2009
Reply by ●April 6, 20092009-04-06
> Could the previous applications of 5v to the UARTs
(both) have
> caused some internal issue that can cause this crosstalk yet MSP
> seems to be working correctly in all other respects?
I very much doubt that. You don't say what MSP you're using (or if you are using the USART or USCI module), but on the ones I've used there is no path through which the data form one UART could get into the other UART. If the second UARTs RX pin is floating (not connected to the device TX or instead connected to the device RX), then it 'could' pick up the TX or RX form the other one.
In any case, did you check the firmware?
Anyway, the only way to be receiving bytes from the other UART is to have the same bitrate (or you'd get wrong characters), so you can easyly test that by changing the baud rate of one of the two UARTs.
By the way, you do realize that all three devices (MSP and both devices connected to it) share a common GND, don't you? Check the GND connections (measure continuity with a tester).
MAX3232 has 2 send and 2 receive circuits. You can use the second one for the second UART. Why aren't you?
Regards,
Michael K.
--- In m..., "merapcb" wrote:
> I have a board where I was, till I discovered the issue, injecting 5v to the UARTs of the MSP (newbie oversight, I know). The electrical issue has been corrected (with MAX3232 for one UART and resistive divider for Rx of the other, Tx not used).
>
> Code downloads and runs on the MSP and UART1 functions correctly.
>
> - BUT -
>
> It seems that data being sent from UART1 is being *received* at UART0. There is no electrical fault on the board.
>
> My question:
>
> Could the previous applications of 5v to the UARTs (both) have caused some internal issue that can cause this crosstalk yet MSP seems to be working correctly in all other respects?
>
> Thanks
>
> caused some internal issue that can cause this crosstalk yet MSP
> seems to be working correctly in all other respects?
I very much doubt that. You don't say what MSP you're using (or if you are using the USART or USCI module), but on the ones I've used there is no path through which the data form one UART could get into the other UART. If the second UARTs RX pin is floating (not connected to the device TX or instead connected to the device RX), then it 'could' pick up the TX or RX form the other one.
In any case, did you check the firmware?
Anyway, the only way to be receiving bytes from the other UART is to have the same bitrate (or you'd get wrong characters), so you can easyly test that by changing the baud rate of one of the two UARTs.
By the way, you do realize that all three devices (MSP and both devices connected to it) share a common GND, don't you? Check the GND connections (measure continuity with a tester).
MAX3232 has 2 send and 2 receive circuits. You can use the second one for the second UART. Why aren't you?
Regards,
Michael K.
--- In m..., "merapcb" wrote:
> I have a board where I was, till I discovered the issue, injecting 5v to the UARTs of the MSP (newbie oversight, I know). The electrical issue has been corrected (with MAX3232 for one UART and resistive divider for Rx of the other, Tx not used).
>
> Code downloads and runs on the MSP and UART1 functions correctly.
>
> - BUT -
>
> It seems that data being sent from UART1 is being *received* at UART0. There is no electrical fault on the board.
>
> My question:
>
> Could the previous applications of 5v to the UARTs (both) have caused some internal issue that can cause this crosstalk yet MSP seems to be working correctly in all other respects?
>
> Thanks
>
