WM1302 GPS timestamp?

I have an WM1302 with a Pi HAT stacked onto a raspberry Pi 5. I am connected to a chirpstack network. My location shows up correctly on the chirpstack map so I feel the GPS is working (global_conf.json)

"gps_tty_path": "/dev/ttyAMA0",

My issue is the time stamp on my uplink data packets is always showing the same timestamp and the year 1999.

my questions:

  1. Are there commands that can be used to monitor the service (lora_pkt_fwd) while pushing a packet to the network? (I am using an Lora-E5 development board and AT commands)

  2. Is 1 pps necessary for timestamp? If so how do I configure or make sure it is configured correctly? (somewhat concerning here is the WM1302 wiki defines the 1 PPS pin as an input and from the perspective of the GPS that is VERY incorrect as 1 PPS is an output)

  3. Any reason why these time stamps would not be correctly handed off to the network server that I may be missing with respect to the gateway?


Hi there,
So it is a an Input for an Optional GPS module on the Gateway side not the other way around.
You check out the Github for it, more info is there. the .05 PPS input resolution would be enough to provide the time stamp based off of the 1 PPS pulse from a Standard GPS module (like the GSS nema one they sell) connecting to both the host MCU and the PPS input for SX1XX radio.

This may give more incite to the many configurations it supports, admittedly I thought the same thing initially. Most accurate when configured that way.
GL :slight_smile: PJ :v:

my SenseCAP S2120 Weather station showed a location too and i was wondering did it have a gps… but it was showing inside the house instead of at its outside location… i found out it used the gps of the iphone on setup to set the location and does not have gps onboard… fyi

Ah yes…My bad it is an output on the GPS…

so I am trying to map I/O within lora_pkt_fwd application for an RPi5. I cannot seem to find schematics for WM1302 or WM1302 Pi Hat. My lora_pkt_fwd that I currently downloaded off of github is

SX1302_RESET_PIN=23     # SX1302 reset
SX1302_POWER_EN_PIN=18  # SX1302 power enable
SX1261_RESET_PIN=22     # SX1261 reset (LBT / Spectral Scan)
AD5338R_RESET_PIN=13    # AD5338R reset (full-duplex CN490 reference design)

The wiki for the WM1302 and Pi Hat don’t even mention SX1302 in pin naming…

pi hat

Basically I am running somwhat blind here as I would like to confirm what the 4 pins above should map to an RPi5 AND to boot I would like to know what pin maps to 1PPS on RPi5?

I have seen code changes re-mapping the above to 17, 18, 5 and 13 respectively but once again I cannot validate this for RPi5.

For what it is worth I am connected to a network server and appear to be working EXCEPT my GPS timestamp as it continually shows a static stamp of year 1999

Just bcz my lora_pkt_fwd and reset_lgw.sh run doesn’t give me any confidence that it correctly is setting the right gpios for reset

hi there,
Yes, I think because that’s newer, 1206 was all there was for a while, initially.
the packet forwarding config is what really pushed the dev on it.
Short of hanging a Logic probe or analyzer hard to say.
You need something in the config to re-route or provide the Sync in place of the GPS
some command that ties it to the 32Khz int clock. I thought there was a command for that or something like it? or tell it to use the ip of the time server… I’ll look around, check out sematech site too.
GL :slight_smile: PJ

check out this thread, about time.

Hello PJ.

btw just to clarify this is NOT TTN but rather Chirpstack server

I will look into that also. I scoped out the pins…This is an WM1302 SPI unit… Pin 12 is troubling…If I use SEEED wiki this says WM1302 SX1262 Busy signal which according to the SX1262 datasheet is an Output not a tri-state signal. (see pics below)…

One more thing the WM1302 pins out 1PPS on pin 19…You would think it would go to the HAT somewhere but the scope does not seem to indicate a simple 1 second pulse on any pin…the closest I get is GPS TXD (why TXD and not RXD seems odd to me) on pin 10 of the hat…No GPS signals (TXD/RXD) are labeled on the WM1302…Leads me to believe the HAT contains GPS stuff and it doesn’t get pinned out to RPi.

Finally…I scoped out 1PPS on the hat and the WM1302…100ms high 1 second period pulse…Looks good. This signal is nowhere to be found on the pinout.

So the real question I have is if the gateway-bridge resides on the RPi5 and it does not get 1PPS would this prohibit it from sending the correct time to the network server (also on the RPi5)?

Maybe I am getting ahead of myself as I have to look at your data you sent…

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