Markus Grönholm / Mbed 2 deprecated GMR-sensor-example

Example for TLE5012B GMR sensor

Dependencies:   mbed

main.cpp@0:1f873630ed4f, 2019-02-07 (annotated)

Committer:
mgronhol
Date:
Thu Feb 07 12:18:49 2019 +0000
Revision:
0:1f873630ed4f
Initial setup

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mgronhol 0:1f873630ed4f 1 #include "mbed.h"
mgronhol 0:1f873630ed4f 2
mgronhol 0:1f873630ed4f 3 Serial pc(SERIAL_TX, SERIAL_RX);
mgronhol 0:1f873630ed4f 4
mgronhol 0:1f873630ed4f 5
mgronhol 0:1f873630ed4f 6 /* This example uses pins A0, A1 and A2 as SSC interface pins */
mgronhol 0:1f873630ed4f 7 DigitalOut SCK( A0 );
mgronhol 0:1f873630ed4f 8 DigitalInOut DATA( A2 );
mgronhol 0:1f873630ed4f 9 DigitalOut CSQ( A1 );
mgronhol 0:1f873630ed4f 10
mgronhol 0:1f873630ed4f 11
mgronhol 0:1f873630ed4f 12
mgronhol 0:1f873630ed4f 13 /*Functions for bit level access to SSC bus */
mgronhol 0:1f873630ed4f 14
mgronhol 0:1f873630ed4f 15 inline void ssc_write_bit( int value ){
mgronhol 0:1f873630ed4f 16 SCK = 0;
mgronhol 0:1f873630ed4f 17 wait_us(1);
mgronhol 0:1f873630ed4f 18 SCK = 1;
mgronhol 0:1f873630ed4f 19 wait_us(1);
mgronhol 0:1f873630ed4f 20 if( value != 0 ){ DATA = 1; } else { DATA = 0; }
mgronhol 0:1f873630ed4f 21 wait_us(1);
mgronhol 0:1f873630ed4f 22 SCK = 0;
mgronhol 0:1f873630ed4f 23 }
mgronhol 0:1f873630ed4f 24
mgronhol 0:1f873630ed4f 25 inline int ssc_read_bit(){
mgronhol 0:1f873630ed4f 26 int out = 0;
mgronhol 0:1f873630ed4f 27 SCK = 0;
mgronhol 0:1f873630ed4f 28 wait_us(1);
mgronhol 0:1f873630ed4f 29 SCK = 1;
mgronhol 0:1f873630ed4f 30
mgronhol 0:1f873630ed4f 31 wait_us(1);
mgronhol 0:1f873630ed4f 32 SCK = 0;
mgronhol 0:1f873630ed4f 33 if( DATA.read() != 0 ){ out = 1; }
mgronhol 0:1f873630ed4f 34
mgronhol 0:1f873630ed4f 35
mgronhol 0:1f873630ed4f 36 return out;
mgronhol 0:1f873630ed4f 37 }
mgronhol 0:1f873630ed4f 38
mgronhol 0:1f873630ed4f 39 /* Functions to read & write 16bit words via SSC */
mgronhol 0:1f873630ed4f 40
mgronhol 0:1f873630ed4f 41 void ssc_write_word( uint16_t word ){
mgronhol 0:1f873630ed4f 42 DATA.output();
mgronhol 0:1f873630ed4f 43 wait_us(1);
mgronhol 0:1f873630ed4f 44 for( int i = 0; i < 16 ; ++i ){
mgronhol 0:1f873630ed4f 45 ssc_write_bit( word & 0x8000 );
mgronhol 0:1f873630ed4f 46 word <<= 1;
mgronhol 0:1f873630ed4f 47 }
mgronhol 0:1f873630ed4f 48 }
mgronhol 0:1f873630ed4f 49
mgronhol 0:1f873630ed4f 50 uint16_t ssc_read_word(){
mgronhol 0:1f873630ed4f 51 uint16_t word = 0;
mgronhol 0:1f873630ed4f 52 DATA.input();
mgronhol 0:1f873630ed4f 53 wait_us(1);
mgronhol 0:1f873630ed4f 54 for( int i = 0; i < 16; ++i ){
mgronhol 0:1f873630ed4f 55 word <<= 1;
mgronhol 0:1f873630ed4f 56 word |= ssc_read_bit();
mgronhol 0:1f873630ed4f 57 }
mgronhol 0:1f873630ed4f 58
mgronhol 0:1f873630ed4f 59 return word;
mgronhol 0:1f873630ed4f 60 }
mgronhol 0:1f873630ed4f 61
mgronhol 0:1f873630ed4f 62 /* And function to read angle from GMR sensor */
mgronhol 0:1f873630ed4f 63 float encoder_read_angle(){
mgronhol 0:1f873630ed4f 64 uint16_t data[2] = {10,10};
mgronhol 0:1f873630ed4f 65 uint16_t cmd = 0x8000 | (2<<4) | 1;
mgronhol 0:1f873630ed4f 66 float angle;
mgronhol 0:1f873630ed4f 67
mgronhol 0:1f873630ed4f 68 /* Request new measurement */
mgronhol 0:1f873630ed4f 69 SCK = 0;
mgronhol 0:1f873630ed4f 70 CSQ = 0;
mgronhol 0:1f873630ed4f 71 wait_us(2);
mgronhol 0:1f873630ed4f 72 CSQ = 1;
mgronhol 0:1f873630ed4f 73 wait_us(2);
mgronhol 0:1f873630ed4f 74
mgronhol 0:1f873630ed4f 75 /* Read angle register */
mgronhol 0:1f873630ed4f 76 SCK = 0;
mgronhol 0:1f873630ed4f 77 CSQ = 0;
mgronhol 0:1f873630ed4f 78 ssc_write_word( cmd );
mgronhol 0:1f873630ed4f 79 wait_us(2);
mgronhol 0:1f873630ed4f 80 data[0] = ssc_read_word(); /* angle */
mgronhol 0:1f873630ed4f 81 data[1] = ssc_read_word(); /* checksum */
mgronhol 0:1f873630ed4f 82 CSQ = 1;
mgronhol 0:1f873630ed4f 83
mgronhol 0:1f873630ed4f 84 /* compute angle from measurement */
mgronhol 0:1f873630ed4f 85 angle = (0x7fff & data[0]) * 360.0f/(32768.0f);
mgronhol 0:1f873630ed4f 86
mgronhol 0:1f873630ed4f 87 return angle;
mgronhol 0:1f873630ed4f 88 }
mgronhol 0:1f873630ed4f 89
mgronhol 0:1f873630ed4f 90 int main() {
mgronhol 0:1f873630ed4f 91 pc.baud( 115200 );
mgronhol 0:1f873630ed4f 92
mgronhol 0:1f873630ed4f 93 while(1) {
mgronhol 0:1f873630ed4f 94 float angle = encoder_read_angle();
mgronhol 0:1f873630ed4f 95 pc.printf( "Angle: %.2f deg\r\n", angle );
mgronhol 0:1f873630ed4f 96 wait( 0.25 );
mgronhol 0:1f873630ed4f 97 }
mgronhol 0:1f873630ed4f 98 }