AGX can gpio setting issue

Autonomous Machines Jetson & Embedded Systems Jetson AGX Xavier
#1

Hi all,
I am trying to set the can gpio as output-high, once it was powed on.
I have tried to configure the pin through pinmux spreadsheets and re-flashing the board with new *.cfg file.
Then both can gpio can set to out-put high after 400ms.

My question:
How to set the can pins to out-put high at the beginning?

I read the AGX boot related documents.
It said the boot sequence: SOC bootroom–>MB1—>MB2—>CBOOT—>Kernel.

The pin related setting through the cfg file should be in MB1 step. Then it has passed 400ms.

Is it anyway to set it before?

Thanks

#3

hello gravin,

could you please also share the actual use-case for reference? thanks

#4

Hi Jerry,

We have several other CAN boards together. As a standard, we require all the CAN boards set GPIO with output-high. Even it delayed 4ms, it will impact other board. So it must be set with output-high, once it was pow on.

Thanks

#5

hello gravin,

it might be pinmux is overwritten by something else like prod or pmic. may I know which pin you’re using.

#6

can
can1920×1606 124 KB

Hi Jerry,

I used the can0 and can1 output GPIO.

By default, can0 was set as low level output.
So I modified the tegra19x-mb1-pinmux-p2888-0000-a04-p2822-0000-b01.cfg
pinmux.0x0c303000 = 0x0000c059; # can1_dout_paa0: rsvd1, pull-up, tristate-enable, input-enable
pinmux.0x0c303008 = 0x0000c059;

Then it worked. It was the same behavior.
Because can0 was set pull down by xml file.

However,

From the picture, we can find that there was low level output for both can0 and can1 for about 400ms from power on.

I want to fix this duration about the low level.

Thanks.

#7

Hi Jerry,

It maybe set by pro-Pin state in xml file.
According to the description about this filed, it says that:

POR – Pin state at reset/power on.
Z (Pin tri-stated)
PU/1 (Pin pulled down)
PD/0 (Pin pulled up)

By default, it was set as pu in xml.

However, I set it as pu. And generate the dtsi,
There is no change in dtsi,
How to modify this filed?

Thanks

#8

hello gravin,

could you please confirm the timing from power-on to mb1 execution for setting pinmux.
thanks

#9

Hi Jerry,

From the picture attached before, it was about 400ms.

Thanks

#10

HI Jerry,

Any suggestion? we need to fix this issue ASAP. Our project is delayed by this issue.

Thanks