To activate the usart on the CTS pin


#1

How to activate brought by usart on the CTS and RTS pins?


#2

Serial hardware flow control is not supported. For simple cases, you can drive a serial device’s CTS manually using any digital output to determine if the serial device should be sending the Photon data (LOW=send data, HIGH=stop). The problem is that there isn’t support for RTS to stop the flow of serial data out of the serial buffer to the serial device.


#3

hi. thank you for help. is it same so the redbear letting?


#4

Hardware flow control support is scheduled for 0.6.0: https://github.com/spark/firmware/pull/930

Core: Serial1 (CTS - A0, RTS - A1)
Photon/Electron: Serial2 (CTS - A7, RTS - RGBR (which will require some tinkering to access))


#5

thank you a lot for help.


#6

Hi, did hardware flow control get added to electron? I’m looking to do some bidirectional communication on USART1 and didn’t seen any notes in the documentation to reflect this PR.

Thanks!


#7

It was, however hardware flow control (CTS/RTS) is only available on Serial2 on the Photon and Electron.

Unfortunately Serial2 connected to the pins that operate the RGB LED, so you need to remove that (or its current-limiting resistors) in order to use hardware flow control on the Photon and Electron. CTS is A7 and RTS is RGBR.

This is how you access Serial2 on the Photon:

https://docs.particle.io/support/particle-devices-faq/photon-serial2-faq/


#8

Thanks for the fast response! You’re right, the hw mods seem painful at scale, so I think handling in our software is the more efficient way to go. I appreciate the clean info though!