FlexComm UART half duplex operation

[simonwood]

I am looking at using an LPC51U68 for an upcoming project which involves a number of half duplex serial interfaces. 

Is there a way to internally run half duplex using the FlexComm in UART mode that requires only 1 pin to be used?

Obviously I can simply join the TX and RX pins externally and change the pin functions as needed to give half duplex operation, but this consumes an extra pin.  

TIA.

[diego_charles]

Hi Tom,

 I can tell that  the device does not have a pin with both TX and RX functionality using the same FLEXCOM interface. Therefore , it is not possible to use single  Flexcomm interface and a single pin for TX and RX.

I have obtained that conclusion after  checking the   LPC51U68 User manual   (UM11071) tables, where pin functionality is described.

Table 188. Type D I/O Control registers: FUNC values and pin functions for port 0

Table 192. Type I I/O Control registers: FUNC values and pin functions

Table 194. Type A I/O Control registers: FUNC values and pin functions

I hope this could help!

Yours,

Diego.

[simonwood]

Thanks Diego - I'd also got that far from the datasheet, just wondered if there were any other thoughts on this.

If you could take back a product request - add half duplex option to the USART options in the flexcomm unit. There are so many systems that operate single wire serial, and losing pins (given the high overlap between match outputs and flexcomm functions) hurts. Going to a higher pin count package doesn't help as the variable pin features are all on the low number pins!

Either that or bring back the SWM (as per 8xx and 15xx) - SWM is fantastic and allows all these issues to be sorted.

Merry Christmas.

[diego_charles]

Hi @simonwood 

Unfortunately,  I am not related to any product request team, but  I want thank you for your feedback and comments! 

Merry Christmas and  happy new year!

Diego