XA1110 issues using interrupt


I am making a project using one of the GPS XA1110 breakout board (https://www.sparkfun.com/products/14414). The board I am using to control it is a 9DoF Razor IMU M0 that has a SAMD21 chip on it, essentially making it an Arduino Zero (https://www.sparkfun.com/products/14001). However, I am experiencing issues using the interrupt on the GPS board. My first iteration of code didn’t use the GPS interrupt, but polled the GPS instead and i was able to get data out of it. In my other version of the code I use the interrupt by hooking it up to the Razor on a pin and using the function:

attachInterrupt(digitalPinToInterrupt(interrupt_pin), GPSisr, LOW);

I did some testing and found out that it seems like the pin is always HIGH (I used my code to display the state of the pin and a voltmeter directly to the GPS to see if it changed). I also made some simple code that read the PPS signal as an interrupt to send to the serial monitor each second counting up, and it worked well.

So is there some sort of special setup I need to do to have the GPS send interrupt signals or anything else? It’s been a real headache for the past few days so I hope there is a solution somewhere.