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PSoC™ 5, 3 & 1 Forum Discussions

PeCa_4386336
Level 2
Level 2
5 replies posted First reply posted First question asked

I've been using the 8-bit UART in a design for some time. I've recently changed from the internal 24M clock to using external 32.768kHz cystal and the PLL to generate a 23.986MHz internal clock. Now the UART does not seem to work reliably. I'm talking to a PC and if I change the baud rate around the nominal 19200 I get either the Tx or Rx to work but not both at the same time. It's as if the Rx and Tx are using different clocks. I know the internal clock is at the right frequency by putting an 8 bit counter in a digital block and dividing down VC3 and feeding to a pin. I get exactly the expected frequency. The difference between 24M and 23.986M should just make the baud rate closer to the nominal value.

Any thoughts?

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3 Replies
SampathS_11
Moderator
Moderator
Moderator
250 sign-ins 250 solutions authored 5 questions asked

Kindly check if ClockSync parameter of the UART User Module is set to "Sync to SysClk". Hopefully this should resolve the issue.

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Thank you for your reply. The ClockSync parameter is set to "Sync to SysClk" already. Do you have any other ideas?

Regards

Peter

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- Does this issue of either TX or RX working correctly happen at 19,200 baud or other bauds also?

- Is there any level translator between PC and PSoC, which can cause this issue.

- Is the PC serial port configured correctly with respect to parity, stop bits?

Best regards,

Sampath Selvaraj

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