UART2 on J90

Autonomous Machines Jetson & Embedded Systems Jetson TX2
1

Using JetPack 3.3 on a J90 firmware version 1.6 patched to get USB3 working, I’m having trouble getting the UART2 port working. I tried both connecting TX and RX together as well as a USB cable to a PC. Currently /dev/THS1-3 are showing up as devices, however, these aren’t showing any output on /dev/THS1-3 or /dev/S0-3 using minicom.

UART0 works on /dev/ttyS0 on the J90, but we can’t use that as it is console and not DMA.

I also tried it on the dev board J17 and I’m not getting anything there either. If I flash with the device tree of the J90 does this break the dev board’s interface?

From much reading on the forums, there are patches to get the UART working, but I think most of them don’t apply to the versions I’m using, is this correct, or do I need to patch something to get this working? I’m not entirely sure where in the device tree to look to make sure it is enabled/mapped properly, could I get some pointers?

Thanks

Edit: Dev board J17 UART1 does work with both the jetpack 3.3 default flash and the J90 firmware changes. Still can’t get J90 uart to work with their firmware or a built one from their sources.

From the J90 spec:
“UART2_TXD / SWCLKB16UART 0 console port (3.3V TTL level): transmit data output (RN24 must be installed) J90 with MCU: SWCLK”

What is RN24? Also, it is labeling uart2 port as uart0 console… Is that a typo? (Both UART0 and UART2 ports in the description say UART0 console…

2

Hi, you’d better to ask vendor of J90 for help. For TX2, all ports are validated before ship out.

3

I submitted a ticket with them, waiting on a reply.

Is there a way to verify uart2 on the dev board? The only header I saw was on the m2 connector. I suppose I could try getting the camera working as it is on uart2.

4

Hi acwatkins, your ticket has been answered.

But for everybody else that wants to get UART2 to work, please populate the spot marked as RN24 with a 0 or 10 Ohm resistor (we use EXB-N8V100JX).

J90 UART2 Patch.png
J90 UART2 Patch.png1327×798 352 KB

5

Hi everybody,

are you serious ???

you says that we do put a micro-resistor to obtain the uart_tty2 working ?

seem’s you have write the in your documentation and website that it was available :

The “J90” is the fully featured version: 2x UART, 2x CSI-2.

And how did we realise this modification in our kitchen ???

regard’s.