How to trigger a time mark message on GPS-RTK-SMA with EXTINT

GPS/GNSS Development Boards
1

I have a GPS-RTK-SMA board. I want to trigger a time mark message (UBX-TIM-TM2) by signalling the EXTINT channel of the Ublox ZED-F9P module. I am assuming that the INT pin of the board is connected to the EXTINT channel of the module.

According to the Ublox manual, a rising or falling edge on the channel is supposed to trigger the time mark message. When I apply the signal to the pin, however, I do not receive it.

The following are steps I used to set up the module to enable the messages: enabled incoming UBX messages over USB; set the measurement rate to 1 second; set the CFG-MSGOUT-UBX_TIM_TM2_USB configuration item to a value of 1; connected the unit to an antenna and got a 3D fix position.

The time mark messages are not received over USB. Is there anything here that I am missing?

2

We haven’t tried using the INT pin but it looks like it’s disabled by default in the Ublox firmware. There’s probably a setting somewhere inside [U-Center that configures and enables that pin but I don’t know off hand where in U-Center to look.](u-center)

3

I found UBX-CFG-ESRC (external source config) in the Configuration View in U-Center. Changing the values results in the message being NACK’ed. That message is also not documented in the ZED-F9P manual.

I didn’t see anything else in U-Center.

4

I’d go look for an existing answer on Ublox’s own forums, and if there isn’t one then ask over there. Lots of expertise there.

5

Unfortunately we don’t have an answer for you, Ublox has a [forum where you might find help with this.

If you find a solution, please update this post as there may be others that are trying to do the same thing.](https://portal.u-blox.com/s/topic/0TO2p0000009r46GAA/ublox-community-forum)

6

I figured it out. We were applying positive voltage to the INT pin when we should have been connecting it to ground . Thanks everybody for your help.