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Issues with auto CTS/RTS hardware flow control feature on Vybrid platform

Question asked by Bhuvanchandra DV on May 21, 2015
Latest reply on May 27, 2015 by Bhuvanchandra DV



I'm testing the auto RTS/CTS hardware flow control feature available on Vybrid lpuart port, with the mainline fsl_lpuart driver.


As per the reference manual RXRTSE and TXCTSE bits in UARTx_MODEM register will enable the auto RTS/CTS hardware control.


Vybrid lpuart as receiver: RXRTSE enabled:

If the receiver request-to-send functionality is enabled, the receiver automatically

deasserts RTS if the number of characters in the receiver data register is equal to or

greater than receiver data buffer's watermark, RWFIFO[RXWATER]....


Auto RTS control was working as expected, tested by sending data from CP2108-EK board to Vybrid lpuart.


Vybrid lpuart as transmitter: TXCTSE enabled:

If the clear-to-send operation is enabled, the character is transmitted when CTS

is asserted. If CTS is deasserted in the middle of a transmission with characters remaining

in the receiver data buffer, the character in the shift register is sent and TXD remains in

the mark state until CTS is reasserted...


Auto CTS control was not working as expected, data was not transferred even when CTS was asserted.


Did anyone verified the auto RTS/CTS hardware flow control feature on Vybrid lpuart ?


Best regards,