ZYNQ Board external clock direct to FPGA

Embedded Development Boards, Kits, Programmers
1

This is a high-precision application.
We’re using a AMD ZCU104 board.

We have a 1PPS signal generated externally.
The 1PPS signal must be sent to the ZYNQ board and go directly to the FPGA where we have a Finite State Machine. This must happen with no delays due the processor, extraneous logic or use of interrupts.

Can this signal go directly from external pin on the ZYNQ board to the FPGA?
For example, from external pin G8, to PMOD 0_0, to GPIO 0_0 on the FPGA.

2

Hello markatmerlintps

I’m checking on this to see there is anyone who can assist you with this.

3

Welcome back @markatmerlintps,

Understood, you have a PNT application that requires a rock-solid PPS (likely GPS derived).

Thoughts:

  1. What is the logic level of your PPS? As memory serves, the ZYNQ has 3.3. VDC logic. You may or may not need a level shifter. Be sure to carefully review the data sheet for PPS and the ZYNQ board.

  2. Recommend use of a synchronizer. This will delay you PPS, but by a known ammount.

  3. Depending on you timing requirements, the PPS may not be good enough as you will have jitter equal to the clock period of the FPGA. Please consider this article.

Sincerely,

Aaron

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4

Aaron,

Thanks much. We’ll look at the article. This question is about how to get the 1PPS signal which is external, to the FPGA without going through the processor or any extraneous logic that would cause variable delay. So I think it’s really a question about use of the ZYNQ board itself.

5

In the linux subsystem there is a generic pps gpio driver, here is one example how to enable it. Just make sure you sync the pps ttl level with the gpio logic.

pps gpio: AMD Customer Community

Regards,

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