Compass 2 click

Compass 2 click carries the AK8963 3-axis electronic compass. The AK8963 sensor is based on the Hall effect. The click is designed to run on a 3.3V power supply only. It communicates with the target microcontroller through either I2C or SPI interface, with additional functionality provided by the INT pin on the mikroBUS™ line.

AK8963 features

The built-in ADC converter can be set up at either 14 or 16 bit resolution, for each of the 3 axes. The sensitivity is 0.6µT/LSB typ. at 14-bit, and 0.15µT/LSB at 16-bit.

AK8963 incorporates magnetic sensors for detecting terrestrial magnetism in the X-axis, Y-axis, and Z-axis, a sensor driving circuit, signal amplifier chain, and an arithmetic circuit for processing the signal from each sensor.

Key features

• AK8963 electronic compass
  • Built-in ADC converter
  • 14-/16-bit selectable resolution
  • Sensitivity: 
    • 0.6 µT/LSB typ. (14-bit)
    • 0.15µT/LSB typ. (16-bit)
• I2C or SPI interface
• 3.3V power supply

Specification

Pinout diagram

This table shows how the pinout on Compass 2 click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin	mikroBUStm				Pin	Notes
External trigger pulse input pin	TRG	1	AN	PWM	16	NC	Not connected
Reset pin	RST	2	RST	INT	15	INT	Interrupt
Chip Select	CS	3	CS	TX	14	NC	Not connected
Serial Clock input pin	SCK	4	SCK	RX	13	NC	Not connected
SPI Master Input Slave Output	MISO	5	MISO	SCL	12	SCL	I2C Clock
SPI Master Output Slave Input	MOSI	6	MOSI	SDA	11	SDA	I2C Data
Power supply	+3.3V	7	3.3V	5V	10	NC	Not connected
Ground	GND	8	GND	GND	9	GND	Ground

Features and usage notes

The AK8964 has several operating modes which can be configured by setting a specific register (CNTL1) to certain values. The following is a list of available operating modes with partial descriptions (to give you an overview). The configuration details are available on page 13 of the official data sheet, while the complete descriptions

(1) Power-down mode

Power to almost all internal circuits is turned off. All registers are accessible in power-down mode. However, fuse ROM data cannot be read correctly. Data stored in read/write registers are remained. They can be reset by soft reset.

(2) Single measurement mode

When single measurement mode (MODE[3:0]=“0001”) is set, sensor is measured, and after sensor measurement and signal processing is finished, measurement data is stored to measurement data registers (HXL to HZH), then AK8963 transits to power-down mode automatically.

(3) Continuous measurement mode 1 and 2

When continuous measurement mode 1 (MODE[3:0]=“0010”) or 2 (MODE[3:0]=“0110”) is set, sensor is measured periodically at 8Hz or 100Hz respectively. When sensor measurement and signal processing is finished, measurement data is stored to measurement data registers (HXL ~ HZH) and all circuits except for the minimum circuit required for counting cycle lentgh are turned off (PD).

(4) External trigger measurement mode

When external trigger measurement mode (MODE[3:0]=“0100”) is set, AK8963 waits for trigger input. When a pulse is input from TRG pin, sensor measurement is started on the rising edge of TRG pin. When sensor measurement and signal processing is finished, measurement data is stored to measurement data registers (HXL to HZH) and all circuits except for the minimum circuit required for trigger input waiting are turned off (PD state).

(4) External trigger measurement mode

Fuse ROM access mode is used to read Fuse ROM data. Sensitivity adjustments for each axis is stored in fuse ROM.

Compass 2 click has both SPI and I2C interfaces. The active interface is configured with onboard jumpers. If you use I2C, an additional jumper will allow you to set the I2C address.

Programming

This code snippet initiates Compass 2 with I2C communication, and reads out the heading value, along with a direction, ( N, NE, E, etc ) from the module to a UART terminal every 100 ms.

  1 #include <stdint.h>
  2 #include "compass2_hw.h"
  3 
  4 sbit COMPASS2_CS at GPIOD_ODR.B13;
  5 
  6 void system_setup( bus_mode_t mode, uint8_t addr );
  7 
  8 float mRes;                  // scale resolutions per LSB for the sensors
  9 uint8_t asax, asay, asaz;
 10 float adjusted_ASAX, adjusted_ASAY, adjusted_ASAZ;
 11 float heading, adjusted_MX, adjusted_MY, adjusted_MZ, magbias[3];
 12 int16_t mx, my, mz;
 13 char text[20] = { 0 };
 14 
 15 void main()
 16 {
 17   // Local Declarations
 18         uint8_t address = 0x0F;
 19         bus_mode_t my_mode = I2C;
 20         float heading = 0;
 21         char uart_text[5] = { 0 };
 22 
 23         system_setup( my_mode, address );
 24 
 25         while(1)
 26         {
 27             compass2_get_all_values( &mx, &my, &mz );
 28             heading = compass2_get_compass_heading( mx, my, mz );
 29 
 30             if( heading < 0 )
 31                 heading += 360;
 32 
 33             UART1_Write_Text( "Heading: " );
 34             FloatToStr( heading, text );
 35             UART1_Write_Text( text );
 36             UART1_Write_Text( " Direction: " );
 37 
 38             if( heading >= 330 || heading <= 30 )
 39             {
 40                 uart_text[0] = 'N';
 41                 uart_text[1] = 'n';
 42             }
 43             else if( heading >= 300 && heading <= 330 )
 44             {
 45                 uart_text[0] = 'N';
 46                 uart_text[1] = 'W';
 47                 uart_text[2] = 'n';
 48             }
 49             else if( heading >= 240 && heading <= 300)
 50             {
 51                 uart_text[0] = 'W';
 52                 uart_text[1] = 'n';
 53             }
 54             else if( heading >= 210 && heading <= 240 )
 55             {
 56                 uart_text[0] = 'S';
 57                 uart_text[1] = 'W';
 58                 uart_text[2] = 'n';
 59             }
 60             else if( heading <= 210 && heading >= 150 )
 61             {
 62                 uart_text[0] = 'S';
 63                 uart_text[1] = 'n';
 64             }
 65             else if( heading <= 150 && heading >= 120 )
 66             {
 67                 uart_text[0] = 'S';
 68                 uart_text[1] = 'E';
 69                 uart_text[2] = 'n';
 70             }
 71             else if( heading <= 120 && heading >= 60 )
 72             {
 73                 uart_text[0] = 'E';
 74                 uart_text[1] = 'n';
 75             }
 76             else if( heading <= 60 && heading >= 30 )
 77             {
 78                 uart_text[0] = 'N';
 79                 uart_text[1] = 'E';
 80                 uart_text[2] = 'n';
 81             }
 82 
 83             UART1_Write_Text( uart_text );
 84             UART1_Write_Text( "rn" );
 85 
 86             Delay_ms(100);
 87         }
 88 
 89 }
 90 
 91 void system_setup( bus_mode_t mode, uint8_t addr )
 92 {
 93         // GPIOs
 94         GPIO_Digital_Output( &GPIOB_BASE, _GPIO_PINMASK_13 );
 95 
 96         // UART
 97         UART1_Init( 9600 );
 98         UART1_Write_Text( "UART Initializedrn" );
 99 
100         // I2C
101         I2C1_Init_Advanced( 100000, &_GPIO_MODULE_I2C1_PB67 );
102         UART1_Write_Text( "I2C Initializedrn" );
103 
104         // Compass 2
105         UART1_Write_Text( "Getting Device ID..." );
106         compass2_hw_init( addr, mode );
107         UART1_Write_Text( "Compass Initializedrn" );
108 
109         // Compass 2 setup
110         mRes = compass2_set_scale_factor( RES_16 );
111         magbias[0] = +470;
112         magbias[1] = +120;
113         magbias[2] = +125;
114 
115         compass2_get_self_test( &mx, &my, &mz );
116         UART1_Write_Text( "x y z Values: " );
117         LongWordToStr( mx, text );
118         UART1_Write_Text( text );
119         UART1_Write_Text( "t" );
120         LongWordToStr( my, text );
121         UART1_Write_Text( text );
122         UART1_Write_Text( "t" );
123         LongWordToStr( mz, text );
124         UART1_Write_Text( text );
125         UART1_Write_Text( "rn" );
126 
127         compass2_get_adjustment( &asax, &asay, &asaz );
128         adjusted_ASAX = ( (float)asax - 128 ) / 256 + 1;
129         adjusted_ASAY = ( (float)asay - 128 ) / 256 + 1;
130         adjusted_ASAZ = ( (float)asaz - 128 ) / 256 + 1;
131 
132         compass2_set_mode( MODE_CONT_1 );
133         compass2_set_scale_factor( RES_16 );
134 
135         UART1_Write_Text( "Compass2 Setup Completed..rn" );
136 }

Code examples that demonstrate the usage of Compass 2 click with MikroElektronika hardware, written for mikroC for ARM, AVR, dsPIC, FT90x, PIC and PIC32 are available on Libstock

Downloads

 mikroBUS™ Standard specification 

 LibStock: Compass 2 click library