BerryGPS-IMU compatibility with MacArthur HAT

[leluck]

I've read through the thread and did a search using BerryGPS as the search term and did not see any prior questions/discussions about using the BerryGPS-IMU with the MacArthur HAT.  I noted that various sensor inputs can be made through the I2C input to the MacArthur HAT.  

I have tinkered with the BerryGPS-IMU V3 and a Raspberry Pi 3B using the GPIO pins for power and data with the BerryGPS-IMU mounted on the Pi.  

I saw that the MacArthur HAT is stackable with some other HATs.  Can the BerryGPS-IMU V3 or V4 be stacked on the MacArthur HAT for power and direct input of its data?  

I am very much looking forward to purchasing a MacArthur HAT and building a navigation computer for my sailboat.  

Sailoog requested that I provide the BerryGPS-IMU V3 pinout.  My knowledge of electronics/coding is quite limited but here is a link to the quick start guide for the BerryGPS-IMU that includes information on both V3 and V4 with a schematic for the V4 version.  I hope it provides sufficient information.  https://ozzmaker.com/berrygps-berrygps-i...art-guide/

Many thanks.

[RussNelson]

They certainly can be physically mated. It goes like this:
1) Raspberry Pi
2) long pin 40-pin connector
3) MacArthur HAT
4) short pin 40-pin connector
5) BerryGPS-IMU.
   
You only need the short-pin connector if you're using the Polulo 12V to 5V power supply. You should use the appropriate length standoffs to bolt everything together.

I haven't checked yet to see if the 10 pins used for BerryGPS-IMU conflict with any the MacArthur HAT pin usage. Hopefully not! Then there's software support, but that's not something I'll worry about for now, because I'm a programmer.

[RussNelson]

Here's a table that shows the pin usage:
RPi, MacArthur, BerryGPS-IMU
1,+3V3,3.3V
2,+5V,PI5V
3,I2C_SDA,SDA
4,+5V,Pi5V
5,I2C_SCL,SCL
6,GND,GND
7,NMEA1_UART3_TX,GPIO4
8,AIS_UART0_TX,TXD_PI
9,GND,GND
10,AIS_UART0_RX,RXD_PI

Sounds like the only real conflict is pin 7. The Berry transmits and receives GPS data on TXD_PI and RXD_PI, which the MacArthur assigns to AIS. I2C is I2c, so as long as you don't have conflicting device IDs, you can reuse I2C pins for multiple devices.

[RussNelson]

Looks like the Berry doesn't actually use GPIO4, so as long as you don't have AIS plugged into the MAIANA socket, and as long as the I2C device IDs don't conflict, there is no hardware conflict.

[RussNelson]

In order to get the BerryGPS seen by GPSD, I had to edit /etc/defaults/gpsd and set DEVICES="/dev/ttyS0", and reboot. Then, from lxTerminal, I could run gpsmon and see it trying to get a fix. I have a metal roof, so I have to hang the GPS receiver out the window to get any kind of fix (which I didn't do, otherwise I'm sure the system would have gotten my location.)