Hi , I’m using TX2-NX SOM with customize designed board, UARTB flow control (PIN103/105) doesn’t work. sudo minicom /dev/ttyTHS1 (set with hw flow control), PIN 103/105 not connect, When RTS/CTS not connect, data input/output shouldn’t success, but it does transfer R/W successful. if change to…

Hi, We have checked and it may be due to status of pin 103. The pin is used for SoC strap and it may be tied to a constant value, affecting the functionality. For further check, please configure the pin to gpio, toggle the GPIO and then observe whether the signal is correct.

Hi, The TX/RX for UARTB is pin 99/101. Do you have further use-case to use pin 103/105?

Hi, What configuration have you done? And I am not sure why you used the case “RTS/CTS” not connected to prove something not work. Have you checked the case which has bot pins connected?

Hi DaneLLL, Yes, we want to use CTS/RTS pin for serial hw flow control. But it doesn’t work . Regards

H WayneWWW, Didn’t do any config for uartb. (using default image) Testing 4-line uart with full function(RX/TX/RTS/CTS), we expect data will not transfer if RTS/CTS are not connect to CTS/RTS. The condition is ,only RX/TX connect to TX/RX , and hw flow control enabled. ===> data can read/write …

Hi DaneLLL, We did patch the code before posting this issue, still not work. And, we also have another 4-line uart on uartc (ttyTHS2) , without patch code , it works fine. only uartb abnormal.

Hi, Since uartc works in your set up and would like to get more information. By default UART3_RTS and UART3_CTS are initialized as GPIO. Do you modify pinmux spreadsheet to initialize the pins to UC3_RTS and UC3_CTS functions?

Hi DaneLLL, Yes, we do set pinmux for all uart pin. also check Linux_for_tegra mb1 pinmux setting Bank: 1 Reg: 0x0c302008 Val: 0x00000458 → uart3_cts_pw5 Bank: 1 Reg: 0x0c302010 Val: 0x00000408 → uart3_rts_pw4 Bank: 1 Reg: 0x0c302018 Val: 0x00000454 → uart3_rx_pw3 Bank: 1 Reg: 0x0c302020 Val: 0…

Hi , Is it possible that uartb hw flow control behavior is not as expect because additional logic on pin103??? [image]

Hi, We are checking with internal team. See if there is further idea about this. Will update.

TX2 NX uartb HW flow control not work

Robotics & Edge Computing Jetson Systems Jetson TX2

DaneLLL May 18, 2022, 6:47am 7

Hi,
Please apply this patch and try again:
Uart flow control on Jetson Nano - #9 by JerryChang

The driver is same for TX1 and TX2 so this patch is required.

Topic		Replies	Views
Orin NX UART1 CTS/RTS failed on JetPack6 Jetson Orin NX uart	7	244	March 13, 2025
Uart flow control on Jetson Nano Jetson Nano hw , uart	8	5571	October 18, 2021
Flow Control on Serial Console Jetson TX2	9	3051	April 20, 2017
UART port setting and behavior Jetson Xavier NX uart	4	709	September 12, 2023
UART1: CTS RTS: flow control is not the same as UART0 Jetson Orin Nano uart	18	1544	May 1, 2024
ttyTHS0 CTS/RTS Jetson Xavier NX uart	27	1171	September 23, 2024
UART1 HW flowcontrol behavior is abnormal Jetson Orin Nano uart , board-design	4	579	October 25, 2023
Apps effect on UART pins Jetson Xavier NX uart	5	503	September 18, 2023
Flow control on UART0 Jetson TX1	1	1423	July 6, 2016
How to force the UART0_RTS pin as low state Jetson Xavier NX uart , board-design	15	1422	December 29, 2023

TX2 NX uartb HW flow control not work

Related topics