topic Re: PPS output imx6ul in i.MX Processors

PPS output imx6ul

Kensou — Thu, 14 Mar 2024 01:07:46 GMT

I have got a Variscite VAR-DART-6UL, which is provided with NXP imx6ul.

My goal is to let the pps ptp signal out and in order to see it via oscilloscope.

I followed the Variscite wiki:

https://variwiki.com/index.php?title=DART-6UL_Eth_IEEE.1588

but output is stuck at 0.

I also tried the solution proposed here: https://community.nxp.com/t5/i-MX-Processors/imx6ul-pps-signal-output/m-p/1793376#M219046

But when I echo the period I receive the error: start time must be greater then current time! Variscite support told me that, since my device tree mods are correct and since PTP/PPS functions are directly in NXP imx6ul device, I have to ask to NXP support.

Could you help me to solve the problem?

Re: PPS output imx6ul

JosephAtNXP — Thu, 14 Mar 2024 18:57:27 GMT

Hi,

Thank you for your interest in NXP Semiconductor products,

There is also this guide from our side that you could review.

Could you share the process told in the guide from your side? With the logs included.

Also, do you enable the pps? Does it exist?

You are using VSC EVK? What ETH port are you using? Could you share the schematics?

Regards

Re: PPS output imx6ul

Kensou — Fri, 15 Mar 2024 08:12:26 GMT

I solved the problem: pps was configured to generate very small pulse every second and my oscilloscope was not able to detect it.

I modified the file drivers/net/ethernet/freescale/fec_ptp.c replacing FEC_HIGH_PULSE with FEC_TMODE_TOGGLE in fec_ptp_enable_pps function in order to generate a square wave.

However, I have got a last question: is there a mannere, also by modifying fec_ptp.c file, to reduce the pps periodicity, generating a square wave of a lower period (i.e. 1ms period)?

Re: PPS output imx6ul

JosephAtNXP — Fri, 15 Mar 2024 19:56:24 GMT

Hi,

You should change the period setting found here,

In this way, you use the same pulses configuration for the FRC and just count less nano seconds. As said by the description, the MAX value is 4,000,000,000 ns.

Regards,

Re: PPS output imx6ul

Kensou — Mon, 18 Mar 2024 07:53:18 GMT

Thank you for your reply, I saw this line but I would like to have a period on the order of 1ms, is it possible or 1second is the minimum period value?