Can the PPS pin of AR8031 on i.MX8-QXP-C0-mek output PPS signal as square waves?

[killedByBugs]

Hi, 

I would like to read the PPS signal from the i.MX8-QXP-C0-mek board to my oscilliscope. I have found a PPS pin (pin 22) connected to AR8031. I have found this pin on the board from the document SPF-29683_D7 in i.MX8QXPDF. (as the following image shows)

Then I did the following steps:

1. run ptp4l:

ptp4l -l 6 -m -i eth0 -p /dev/ptp0 &

2. enable PPS:

echo 1 > /sys/class/ptp/ptp0/pps_enable

3.  change the duty cycle of the PPS clock for a close to 50% ratio

echo "0 0 0 1 1" > /sys/class/ptp/ptp0/period 

After that, I connect the probes of my oscilloscope to the GND pin of the board and pin 22 of AR8031. It seems like I got the wrong output:

Can you please suggest what have I done wrong? Also, please let me know how I get the PPS output signal. 

Thank you in advance.

Kind Regards,

Jim

[JosephAtNXP]

Hi,

Thank you for your interest in NXP Semiconductor products,

You could try to update the ptp setting for the one in reference manual, which is the same in this guide.

If the command adjustment doesn't work, let me know if you could replicate the guide.

Also, what BSP are you working with?

Regards

[killedByBugs]

Hi Joseph, 

Do you mean that I can edit the code of the files which the RM mentioned?:

File Description
drivers/net/ethernet/frescale/fec.h Header file defining registers
drivers/net/ethernet/freescale/fec_ptp.c ENET 1588 timer

My BSP version: imx-6.1.55-2.2.0

I think the steps like "editing fec_ptp.c/fec.h file, running ptp4l, enabling PPS and changing the duty cycle of the PPS clock" are not for the AR8031, it's for the PPS signal from the imx8 CPU. So, I still wonder if the AR8031 can output PPS signal. Also, I would like to know what steps that can enable the PPS signal from the AR8031. 

Thank you.

Kind Regards,

Jim

[JosephAtNXP]

Hi,

I meant run ptp4l as reference manual does:

Transport on UDP IPV4 with E2E delay mechanism: ptp4l -A -4 -H -m -i eth0

Regards,

[killedByBugs]

Hi Joseph,

I have tried the command:

ptp4l -A -4 -H -m -i eth0

After the command on Linux, I probed the TP26(connected to PPS/GPIO out pin of AR8031). It still doesn't work. Do we have any requirement of precision for the oscilloscope to test the PPS output signal? I am not sure if it's my oscilloscope's problem.

Kind Regards,

Jim