Jetson AGX Xavier Test 40 pin hesder for UART RTS/CTS test


I’m tried uart test on my AGX, I set RTS/CTS by using Jetson-IO, and I use USB to UART serial converters on my PC,and I connect to my AGX Xavier 40 pin by Tx/Rx/CTS/RTS, I use the minicom to test, the hardward flow control is Yes, then I disconnected AGX Xavier 40 pin RTC, PC can not send the message to my AGX, but when I disconnected AGX Xavier 40 pin CTS, my AGX still can send the message to the PC.

Does the action correct? Could anyone give me some advise,thanks

hello edward1_lin,

Hardware Flow control is supported using RTS and CTS (hardware/software controlled), please refer to Xavier TRM for the UART chapter.
are you able to probe the pin state for the CTS/ RTS? did RTS always high whether Xavier is sending or receiving?

Hi Jerry,

I use an oscilloscope to check the AGX CTS/RTS pin,

  1. I did not open the minicom, AGX RTS pin is 3.3V, CTS is 0V, my PC RTS is 1.8V CTS is 1.8V
  2. when I opened minicom, both AGX RTS/CTS are 0V, my PC RTS is 0V CTS is 1.8V

In this two case, I did not connect PC and AGX to each other, after that, I connect those device, PC’s RTS to AGX’s CTS, PC’s CTS to AGX’s RTS, then I check the signal, those two connection are low , when I disconnect the PC’s RTS and AGX’s CTS ,those pins are still low, and I could send the message from AGX to PC, but when I disconnect the PC’s CTS and AGX’s RTS , PC’s CTS is 1.8V, AGX’s RTS is low, and it could not send the message from PC to AGX until this line is connected.

Is the AGX’s CTS action correct? If not, how action is correct? how could I fix it?

Hi Jerry,

Do you have any new advice ??

hello edward1_lin,

it’s unnecessary to setup flow control for sending/receiving the data.
how about disable flow control from hardware side, you shall use only Tx/Rx to transmit data packets.

Hi Jerry,

I’m already test that use only Tx/Rx to transmit data packets, It works normally, but I want to check the function RTS/CTS, but it looks like pin36 did not work.

Is pin36 possible to set to CTS? Do you have any idea to test those function?

hello edward1_lin,

RTS/CTS were for notify the data packet is complete transmit/receive.
it’s incorrect to disconnect the pin for flow control.

Hi Jerry,

How can I check RTS/CTS work? Do you have any test plan??

this external wiki page may helps. Flow control (data) - Wikipedia

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