Topics covered in the BerryGPS and BerryGPS-IMU Quick Start Guide;
- BerryGPS-IMU and BerryGPS PCB overview
- How to Assemble BerryGPS
- Connecting BerryGPS and BerryGPS-IMU to a Raspberry Pi
- BerryGPS-IMU and BerryGPS datasheets.
- BerryGPS-IMU and BerryGPS i2c addresses.
- Sample code for IMU
- BerryGPS-IMU Guides and tutorials
uFL connector – This is where the external antenna is connected, using a uFL to SMA adapter.
Switch for external antenna– If an external antenna is connected, this switch should be in the Ext position. When using the internal antenna, it should be in the Int Position.
Super Cap – This super capacitor stores enough energy to keep ephemeris data stored in battery backup RAM for up to 4hrs. This allows for very fast acquisition during power cycles .
Packet Per Second pin and LED – The PPS LED will flash every 1 second and the PPS signal is broken out here. This pin can be used for time syncing of a microcontroller.
Fix pin and LED – The fix LED will flash every 1 seconds when the GPS module has a 3D fix. It is also broken out on a pin, which can be used by a microcontroller to to detect if a 3D fix has been obtained.
GPS Hardware Standby – This pin is used to place the GPS module in a standby state. When set to a LOW state, the GPS module is placed in standby mode and uses <200uA of power. To re-enable, the pin needs to be set to a HIGH state.
This can also be done in software by sending $PMTK161,0*28 to the GPS module. Any other character can be used to wake up from standby mode.
Pins for BerryIMU – If you have a BerryIMU, it can be connected to these pins
All the GPS features are the same as those found in the BerryGPS.
The IMU extra Pins have been broken out onto the PCB, these are;
- INT2_XM – Accelerometer and magnetometer interrupt 1.
- INT1_XM – Accelerometer and magnetometer interrupt 2.
- DRDY_G – Gyroscope data ready.
- INT_G – Gyroscope interrupt.
- DEN_G – Gyroscope data enable.
How to Assemble BerryGPS and BerryGPS-IMU
BerryGPS and BerryGPS-IMU come with one 5×2 female header.
This header needs to be soldered onto the back of the PCB. The image below shows where it is placed;
Connecting BerryGPS and BerryGPS-IMU to a Raspberry Pi
BerryGPS and BerryGPS-IMU sit on top of the raspberry Pi GPIO as shown in the images below.
Datasheets for BerryGPS and BerryGPS-IMU
BerryGPS-IMU I2C Addresses
The default i2c addresses used by the IMU on BerryGPS-IMU are;
- 0x1E for the magnetometer and accelerometer
- 0x6A for the gyroscope
- 0x77 for the pressure sensor
The I2C addresses can be changed from their default be modifing the jumpers ADDR1, ADDR2 and ADDR3 which are found on the back.
Gyroscope I2C address – ADDR1 – By default, this jumper is open, which gives the gyroscope an address of 0x6A. When closed, the address will change to 0x6B. The jumper can be closed by placing a blob of solder on the jumper.
Accelerometer and magnetometer I2C address – ADDR2 – By default, this jumper is open, which gives the accelerometer and magnetometer an address of 0xE1. When closed, the address will change to 0x1D. The jumper can be closed by placing a blob of solder on the jumper.
Pressure senor I2C address – ADDR – By default, this jumper is closed, which gives the pressure sensor an I2C address of 0x77. Opening this jumper will change the I2C address to 0x76. This can be opened by cutting the trace in between the jumper pads with a knife.
BerryGPS-IMU Extra information
The BerryGPS-IMU uses the same sensors found on the BerryIMU. These means that all of the guides and code used for the BerryIMU can also be used with the BerryGPS-IMU.
Sample Code for IMU
Git repository here
The code can be pulled down to your Raspberry Pi with;
BerryGPS-IMU Guides and Tutorials
For the IMU, In this order;
In this order;
Guide to interfacing a Gyro and Accelerometer with a Raspberry Pi
Guide to interfacing a Gyro and Accelerometer with a Raspberry Pi – Kalman Filter
Create a Digital Compass with the Raspberry Pi – Part 1 – “The Basics”
Create a Digital Compass with the Raspberry Pi – Part 2 – “Tilt Compensation”
Create a Digital Compass with the Raspberry Pi – Part 3 – “Calibration”
Create a Digital Compass with the Raspberry Pi – Part 4- “Smartphone Replica”
Converting values from an Accelerometer to Gs – “ Proper Acceleration”