zoe-m8q pps not working?

GPS/GNSS Development Boards
1

I just purchased the zoe-m8q module and have it hooked up to a Raspberry Pi 4. I’m communicating over I2C and Serial with no issues, but I don’t seem to be getting pulse from the PPS pin.

To test, I’ve enabled the dtoverlay in /boot/config.txt by adding

dtoverlay=pps-gpio,gpiopin=4

and enabling it in /etc/modules by adding

pps-gpio

Then testing it using

sudo ppstest /dev/pps0

but I just get

time_pps_fetch() error -1 (Connection timed out)

How can I test to make sure that there is actually a pulse coming off that pin? I want to eliminate the possibility of it being the pi setup wrong.

I do get a response when I touch the wire, which is disconcerting.

2

To check the PPS pin, disconnect it from your Pi and connect a logic probe or a multimeter to PPS. You should be seeing that pin cycle high/low once a second.

3

Okay, so I put a jumper on the ground pin of my Raspberry Pi, and then measured the voltage from the PPS pin and ground. Setting my multimeter to record the max voltage I only ever saw 0.1V. So I’m guessing that either my board is defective (it happens, no big fuss) or there’s a setting in u-center I need to toggle to get PPS to output. Any ideas what setting I need to have configured in u-center to enable PPS?

4

I put a jumper on the ground pin of my Raspberry Pi

Is PPS connected to that ground pin?

5

I am measuring using my multimeter with one lead on the pps pin and the other lead on one of the ground pins of the raspberry pi (which is also providing 3v3 and ground to the gps module)

6

TS-Chris:

I put a jumper on the ground pin of my Raspberry Pi

Is PPS connected to that ground pin?

Oh, I see what you mean, no PPS was connected to GPIO 18. For my test I bridged between the PPS pin of the ZOE-M8Q and ground on the PI as this would have been sufficient to see voltage, however just to be thorough I tested with my meter bridged between PPS and GPIO with the same results.

After looking around in u-center and confirming timepulse was enabled and should have been outputting a pulse every second, I’m fairly convinced I have a bad board. I also noticed that I was unable to set BeiDou to “Enabled”, a feature that the page for the ZOE-M8Q says it has, so that further makes me think that I was one of the lucky few who got a bad board. :lol:

7

If you purchased the board directly off our website, just [fill in the form on this page with your order number and the URL to this forum post and we can replace it for you.

If you purchased from a distributor or Amazon you will need to let them know you have a defective product and arrange with them for an exchange.](Return Policy - SparkFun Electronics)

8

Thanks! I got it on Amazon, and the replacement arrived today with the PPS ticking away perfectly. I’m loving the board so far!