Seeed Grove User manual

3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 1/15
Grove - 3-Axis Digitial Compass v2.0
The Grove - 3-Axis Digital Compass is a digital compass sensor based on Bosch
BMM150. It allows measurement of the magnatic eld in three perpendicular axes
and the output can be read out over I2C and SPI interface, perfectly suitable for 3-
Axis mobile applications.


3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 2/15
This is the second generation of Grove - 3-Axis Digital Compass, comparing to the
rst version, this version can perfectly match the demanding requirements of all 3-
Axis applications while the price is almost half of the rst version, very cost
effective.
[https://www.seeedstudio.com/Grove-3-Axis-Digital-Compass-V2-p-3034.html]
Features
High resolution
High heading accuracy
Easy to use
Specications

3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 3/15
Item Valnue
Working Voltage 3.3V / 5V
Magnetic eld range typical ±1300μT(x, y-axis), ±2500μT(z-axis)
Magnetic eld resolution 0.3μT
Output Degree 0º ~ 360º
Interface I2C
Working Temperature -40℃ to +85 ℃
Dimensions 20mm x 20mm x 15mm
I2C Address 0x13
Platforms Supported
Note
If you want to use multiplue I2C devices, please refer to Software I2C
[http://wiki.seeedstudio.com/Arduino_Software_I2C_user_guide/].

Tip
More details about Grove modules please refer to Grove System
[http://wiki.seeedstudio.com/Grove_System/]


3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 4/15
Arduino Raspberry Pi BeagleBone Wio LinkIt ONE
Getting started
Play with Arduino
Hardware
Step 1. Prepare the below stuffs:
Caution
The platforms mentioned above as supported is/are an indication of the module's software or
theoritical compatibility. We only provide software library or code examples for Arduino
platform in most cases. It is not possible to provide software library / demo code for all
possible MCU platforms. Hence, users have to write their own software library.


3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 5/15
Step 2. Connect Grove-3-Axis_Digitial_Compass_v2.0 to port I2C of Grove-Base
Shield.
Step 3. Plug Grove - Base Shield into Seeeduino.
Step 4. Connect Seeeduino to PC via a USB cable.
Seeeduino V4.2 Base Shield Grove-3-Axis_D
Get One Now
[http://www.seeedstudio.com/Seeeduino-
V4.2-p-2517.html]
Get One Now
[https://www.seeedstudio.com/Base-
Shield-V2-p-1378.html]
Get One Now
[https://www.s
3-Axis-Digital-C
3034.html]

3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 6/15
Seeeduino_v4 Grove-3-Axis_Digitial_Compass_v2.0
5V VCC
GND GND
SDA SDA
SCL SCL
Note
If we don't have Grove Base Shield, We also can directly connect this module to Seeeduino as
below.

Caution


3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 7/15
Software
Step 1. Download the library [https://github.com/Seeed-
Studio/Grove_3_Axis_Compass_V2.0_BMM150] from Github.
Step 2. Refer How to install library
[http://wiki.seeedstudio.com/How_to_install_Arduino_Library] to install library for
Arduino.
Step 3. Create a new Arduino sketch and paste the codes below to it or open the
code directly by the path: File->Examples-
>Grove_3_Axis_Compass_V2.0_BMM150-master->compass
Here is the code
Please plug the USB cable gently, otherwise you may damage the interface.Please use the USB
cable with 4 wires inside, the 2 wires cable can't transfer data. If you are not sure about the wire
you have, you can click here [https://www.seeedstudio.com/Micro-USB-Cable-48cm-p-
1475.html] to buy
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
/**
* This example
*/
#include <Arduino.h>
#include <Wire.h>
// libraries
#include "bmm150.h"
#include "bmm150_defs.h"
BMM150 bmm = BMM150();
void setup()
{
Serial.begin(9600);
if(bmm.initialize() == BMM150_E_ID_NOT_CONFORM) {
Serial.println("Chip ID can not read!");
while(1);
} else {
Serial.println("Initialize done!");
}


3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 8/15
Step 4. Upload the code. If you do not know how to upload the code, please check
how to upload code [http://wiki.seeedstudio.com/Upload_Code/].
Step 5. Open the serial monitor to receive the sensor's data
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
}
void loop()
{
bmm150_mag_data value;
bmm.read_mag_data();
value.x = bmm.raw_mag_data.raw_datax;
value.y = bmm.raw_mag_data.raw_datay;
value.z = bmm.raw_mag_data.raw_dataz;
float xyHeading = atan2(value.x, value.y);
float zxHeading = atan2(value.z, value.x);
float heading = xyHeading;
if(heading < 0)
heading += 2*PI;
if(heading > 2*PI)
heading -= 2*PI;
float headingDegrees = heading * 180/M_PI;
float xyHeadingDegrees = xyHeading * 180 / M_PI;
float zxHeadingDegrees = zxHeading * 180 / M_PI;
Serial.print("Heading: ");
Serial.println(headingDegrees);
delay(100);
}

3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 9/15
Step 6. Within these 3 seconds， please tilt and rotate the compass back and forth
on every axis, as shown in the picture below.
The calibration period time can be changed through the parameter timeout in the
fuction calibrate(uint16_t timeout).
Note


3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 10/15
Step 7. Finally, you will see the something like the following picture.
Enjoy your compass!
Play With Raspberry Pi (With Grove Base Hat for Raspberry Pi)
Hardware
Step 1. Things used in this project:
The compass needs to be calibrated, otherwise you will get the inaccurate data! Please make
sure you have done the Step 5.
Tip
Heading value is in range of 0º ~ 360º, this value is for Y axis, 0º means Y axis points at North,
90º means Y axis points at West, 180º means Y axis points at South, 270º means Y points at
East.


3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 11/15
Step 2. Plug the Grove Base Hat into Raspberry.
Step 3. Connect the 3-axis compass to I2C port of the Base Hat.
Step 4. Connect the Raspberry Pi to PC through USB cable.
Raspberry pi Grove Base Hat for RasPi Grove - 3-axis
Get ONE Now
[https://www.seeedstudio.com/Raspberry-
Pi-3-Model-B-p-2625.html]
Get ONE Now
[https://www.seeedstudio.com/Grove-
Base-Hat-for-Raspberry-Pi-p-
3186.html]
Get ONE Now
[https://www.
3-Axis-Digital
3034.html]

3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 12/15
Software
Step 1. Follow Setting Software
[http://wiki.seeedstudio.com/Grove_Base_Hat_for_Raspberry_Pi/#installation]
to congure the development environment.
Step 2. Download the source le by cloning the grove.py library.
Note
You are required to install python-mraa and python-upm, see the instruction here
https://github.com/Seeed-Studio/pi_repo#mraa--upm-package-repository-for-raspberry-pi
[https://github.com/Seeed-Studio/pi_repo#mraa--upm-package-repository-for-raspberry-pi] for
more information.

1
2
cd ~
git clone https://github.com/Seeed-Studio/grove.py


3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 13/15
Step 3. Excute below commands to run the code.
Following is the grove_3_axis_compass_bmm150.py code.
1
2
cd grove.py/grove
python grove_3_axis_compass_bmm150.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
from __future__ import print_function
import time, sys, signal, atexit, math
try:
from upm import pyupm_bmm150 as sensorObj
except ImportError:
print('Error: Please install python-mraa python-upm module.\r\n
'See instruction here https://github.com/Seeed-Studio/pi_
def main():
# Instantiate a BMP250E instance using default i2c bus and addr
sensor = sensorObj.BMM150(0, 0x13)
# For SPI, bus 0, you would pass -1 as the address, and a valid
# BMM150(0, -1, 10);
## Exit handlers ##
# This function stops python from printing a stacktrace when yo
def SIGINTHandler(signum, frame):
raise SystemExit
# This function lets you run code on exit
def exitHandler():
print("Exiting")
sys.exit(0)
# Register exit handlers
atexit.register(exitHandler)
signal.signal(signal.SIGINT, SIGINTHandler)
# now output data every 250 milliseconds
while (1):
sensor.update()
data = sensor.getMagnetometer()
print("Magnetometer x: {0:.2f}".format(data[0]), end=' ')



3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 14/15
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
print(" y: {0:.2f}".format(data[1]), end=' ')
print(" z: {0:.2f}".format(data[2]), end=' ')
print(" uT")
xyHeading = math.atan2(data[0], data[1])
zxHeading = math.atan2(data[2], data[0])
heading = xyHeading
if heading < 0:
heading += 2*math.pi
if heading > 2*math.pi:
heading -= 2*math.pi
headingDegrees = heading * 180/(math.pi);
xyHeadingDegrees = xyHeading * 180 / (math.pi)
zxHeadingDegrees = zxHeading * 180 / (math.pi)
print('heading(axis_Y point to): {0:.2f} degree'.format(hea
time.sleep(.250)
if __name__ == '__main__':
main()
Success
If everything goes well, you will be able to see the following result

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
pi@raspberrypi:~/grove.py/grove $ python grove_3_axis_compass_bmm15
Magnetometer x: -34.12 y: 36.71 z: -21.25 uT
heading(axis_Y point to): 317.10 degree
Magnetometer x: -34.49 y: 38.20 z: -16.32 uT
heading(axis_Y point to): 317.92 degree
Magnetometer x: -34.12 y: 38.20 z: -9.87 uT
heading(axis_Y point to): 318.23 degree
Magnetometer x: -32.64 y: 38.94 z: -5.69 uT
heading(axis_Y point to): 320.03 degree
Magnetometer x: -31.52 y: 38.20 z: -2.28 uT
heading(axis_Y point to): 320.47 degree
Magnetometer x: -29.67 y: 38.20 z: 0.38 uT
heading(axis_Y point to): 322.16 degree
Magnetometer x: -26.33 y: 38.20 z: 4.55 uT
heading(axis_Y point to): 325.42 degree
^CExiting


3/18/2019 Grove - 3-Axis Digitial Compass v2.0 - Seeed Wiki
http://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/ 15/15
You can quit this program by simply press Ctrl +C.
Resources
[Library] Grove-3_Axis_Compass_V2.0 lib [https://github.com/Seeed-
Studio/Grove_3_Axis_Compass_V2.0_BMM150]
[PDF] BST-BMM150-Datasheet [https://github.com/SeeedDocument/Grove-3-
Axis_Digitial_Compass_v2.0/raw/master/res/Datasheet.pdf]
[Zip] Grove-3-Axis Digital Compass v2_Eagle File
[https://github.com/SeeedDocument/Grove-3-
Axis_Digitial_Compass_v2.0/raw/master/res/Eagle File.zip]
Tech Support
Please submit any technical issue into our forum [http://forum.seeedstudio.com/]
or drop mail to [email protected] [mailto:techsuppor[email protected]].