Gerrit Pathuis / Mbed 2 deprecated K22F_AS5510_I2C_tst

AS5510, 10 bit Absolute linear Hall Field Sensor with I2C output. Lateral movement measurement for simple 2-pole magnet. Magnet diameter 1mm, length 2mm. Output 10 bit resolution, distance per LSB is 2.0mm/1024, ADC sampling frequency 50 kHz.

Dependencies:   mbed

main.cpp@2:dc991201ff3c, 2015-05-30 (annotated)

Committer:
GerritPathuis
Date:
Sat May 30 19:41:25 2015 +0000
Revision:
2:dc991201ff3c
Parent:
1:79e6ae3a23d8
Child:
3:c57454632e8d
Fist issue

Who changed what in which revision?

UserRevisionLine numberNew contents of line
GerritPathuis 0:de08120b71bd 1 #include "mbed.h"
GerritPathuis 0:de08120b71bd 2 //////////////////////////////////////////////////
GerritPathuis 0:de08120b71bd 3 // Testing AS5510 sensor with K22F //
GerritPathuis 2:dc991201ff3c 4 // test results are sent to Tera Term //
GerritPathuis 2:dc991201ff3c 5 // I2C frequency set @ 400kHz //
GerritPathuis 0:de08120b71bd 6 // //
GerritPathuis 2:dc991201ff3c 7 // Note 1) //
GerritPathuis 2:dc991201ff3c 8 // I2C address 0x1C is used by FXOS8700CQ //
GerritPathuis 0:de08120b71bd 9 // 3-axis accelerometer and 3-axis magetometer //
GerritPathuis 2:dc991201ff3c 10 // //
GerritPathuis 2:dc991201ff3c 11 // Note 2) //
GerritPathuis 2:dc991201ff3c 12 // Without magnet present the AS5510 sensor is //
GerritPathuis 2:dc991201ff3c 13 // expected to output a value of approx 511 //
GerritPathuis 2:dc991201ff3c 14 // (1023/2= 511 //
GerritPathuis 0:de08120b71bd 15 //////////////////////////////////////////////////
GerritPathuis 2:dc991201ff3c 16 Serial pc(USBTX, USBRX); // tx, rx
GerritPathuis 2:dc991201ff3c 17 I2C i2c(PTB3, PTB2); // SDA, SCL (for K22F)
GerritPathuis 0:de08120b71bd 18
GerritPathuis 2:dc991201ff3c 19 const int i2c_slave_addr1 = 0x56; // sensor AS5510 number 1 (7 bits), 0x56 or 0x57
GerritPathuis 2:dc991201ff3c 20 //const int i2c_slave_addr2 = 0x57; // sensor AS5510 number 2 (7 bits), 0x56 or 0x57
GerritPathuis 0:de08120b71bd 21
GerritPathuis 0:de08120b71bd 22 //--- public functions---
GerritPathuis 0:de08120b71bd 23 void init_as5510(void);
GerritPathuis 0:de08120b71bd 24 void read_field(void);
GerritPathuis 0:de08120b71bd 25 int offset_comp(void);
GerritPathuis 0:de08120b71bd 26 void look_for_hardware_i2c(void);
GerritPathuis 0:de08120b71bd 27
GerritPathuis 0:de08120b71bd 28
GerritPathuis 0:de08120b71bd 29 int main()
GerritPathuis 0:de08120b71bd 30 {
GerritPathuis 2:dc991201ff3c 31 i2c.frequency(400 * 1000); // 0.1/0.4/1.0 mHz
GerritPathuis 2:dc991201ff3c 32 wait_ms(2); // Power Up wait
GerritPathuis 0:de08120b71bd 33
GerritPathuis 2:dc991201ff3c 34 look_for_hardware_i2c(); // Hardware present ?
GerritPathuis 2:dc991201ff3c 35 init_as5510(); // Initialize
GerritPathuis 0:de08120b71bd 36
GerritPathuis 0:de08120b71bd 37 //----------Setup register----------------------
GerritPathuis 2:dc991201ff3c 38 while (!offset_comp());
GerritPathuis 2:dc991201ff3c 39 pc.printf("Offset compensation process is completed \r\n");
GerritPathuis 2:dc991201ff3c 40
GerritPathuis 2:dc991201ff3c 41 //----------Get the results----------------------
GerritPathuis 0:de08120b71bd 42 while (true)
GerritPathuis 2:dc991201ff3c 43 read_field(); //----------Read magnetic Field-----------------
GerritPathuis 0:de08120b71bd 44 }
GerritPathuis 0:de08120b71bd 45
GerritPathuis 0:de08120b71bd 46
GerritPathuis 0:de08120b71bd 47 void look_for_hardware_i2c()
GerritPathuis 0:de08120b71bd 48 {
GerritPathuis 0:de08120b71bd 49 pc.printf("\r\n\n\n");
GerritPathuis 0:de08120b71bd 50 pc.printf("Note I2C address 0x1C used by FXOS8700CQ 3-axis accelerometer and 3-axis magetometer\r\n");
GerritPathuis 0:de08120b71bd 51 pc.printf("Start hardware search..... \r\n");
GerritPathuis 0:de08120b71bd 52
GerritPathuis 0:de08120b71bd 53 int count = 0;
GerritPathuis 0:de08120b71bd 54 for (int address=12; address<256; address+=2) {
GerritPathuis 2:dc991201ff3c 55 if (!i2c.write(address, NULL, 0)) { // 0 returned is OK
GerritPathuis 0:de08120b71bd 56 pc.printf(" - I2C device found at address 0x%02X\n\r", address >>1);
GerritPathuis 0:de08120b71bd 57 count++;
GerritPathuis 0:de08120b71bd 58 }
GerritPathuis 0:de08120b71bd 59 }
GerritPathuis 0:de08120b71bd 60 pc.printf("%d devices found \n\r", count);
GerritPathuis 0:de08120b71bd 61 }
GerritPathuis 0:de08120b71bd 62
GerritPathuis 0:de08120b71bd 63 void init_as5510()
GerritPathuis 0:de08120b71bd 64 {
GerritPathuis 0:de08120b71bd 65 int i2c_adrs=0;
GerritPathuis 0:de08120b71bd 66 char idata[2];
GerritPathuis 0:de08120b71bd 67 int result=0;
GerritPathuis 0:de08120b71bd 68
GerritPathuis 0:de08120b71bd 69 pc.printf("\r\n");
GerritPathuis 0:de08120b71bd 70 pc.printf("Start AS5510 init.. \r\n");
GerritPathuis 0:de08120b71bd 71
GerritPathuis 0:de08120b71bd 72 i2c_adrs= (i2c_slave_addr1 << 1); // AS5510 Slave address lsb= 0 for write
GerritPathuis 2:dc991201ff3c 73
GerritPathuis 2:dc991201ff3c 74 //---------- Magnet selection --------------------------------
GerritPathuis 2:dc991201ff3c 75 //----0x00= <50mT-----------Strong magnet
GerritPathuis 2:dc991201ff3c 76 //----0x01= <25mT
GerritPathuis 2:dc991201ff3c 77 //----0x02= <18.7mT
GerritPathuis 2:dc991201ff3c 78 //----0x03= <12.5mT---------Weak magnet
GerritPathuis 2:dc991201ff3c 79 //-----------------------------------------------------------
GerritPathuis 0:de08120b71bd 80 idata[0]=0x0B; // Register for Sensitivity
GerritPathuis 2:dc991201ff3c 81 idata[1]=0x00; // Byte
GerritPathuis 0:de08120b71bd 82 result= i2c.write(i2c_adrs, idata, 2, 0); // Now write_sensitivity
GerritPathuis 0:de08120b71bd 83 if (result != 0) pc.printf("No ACK bit! (09)\n\r");
GerritPathuis 0:de08120b71bd 84
GerritPathuis 2:dc991201ff3c 85 //----------- Operation mode selection------------------------
GerritPathuis 0:de08120b71bd 86 idata[0]=0x02; // 0x02 address setup register for operation, speed, polarity
GerritPathuis 0:de08120b71bd 87 idata[1]=0x04; // Normal Operation, Slow mode (1), NORMAL Polarity (0), Power Up (0)
GerritPathuis 0:de08120b71bd 88 result= i2c.write(i2c_adrs, idata, 2, 0); // Now write_operation
GerritPathuis 0:de08120b71bd 89 if (result != 0) pc.printf("No ACK bit! (11)\n\r");
GerritPathuis 0:de08120b71bd 90
GerritPathuis 0:de08120b71bd 91 pc.printf("AS5510 init done\r\n");
GerritPathuis 0:de08120b71bd 92 }
GerritPathuis 0:de08120b71bd 93
GerritPathuis 0:de08120b71bd 94
GerritPathuis 0:de08120b71bd 95 int offset_comp(void)
GerritPathuis 0:de08120b71bd 96 {
GerritPathuis 0:de08120b71bd 97 int adrss=0;
GerritPathuis 0:de08120b71bd 98 int oresult=0;
GerritPathuis 0:de08120b71bd 99 char off_data[2];
GerritPathuis 0:de08120b71bd 100 int ocf_done=0;
GerritPathuis 0:de08120b71bd 101
GerritPathuis 0:de08120b71bd 102 // First, now Write pointer to register 0x00----------------------------
GerritPathuis 0:de08120b71bd 103 adrss= (i2c_slave_addr1 << 1); // AS5510 Slave address lsb= 0 for write
GerritPathuis 0:de08120b71bd 104 oresult= i2c.write(adrss, 0x00, 1, 0); // write one byte
GerritPathuis 0:de08120b71bd 105 if (oresult != 0) pc.printf("No ACK bit! (33)\n\r");
GerritPathuis 0:de08120b71bd 106
GerritPathuis 0:de08120b71bd 107 // Second, now Read register 0x00 and 0x01--------------------------------
GerritPathuis 0:de08120b71bd 108 memset(off_data, 0, sizeof(off_data));
GerritPathuis 0:de08120b71bd 109 adrss= (i2c_slave_addr1 << 1) | 0x01; // AS5510 address lsb= 1 for read
GerritPathuis 0:de08120b71bd 110 oresult= i2c.read(adrss, off_data, 2, 0); // read two bytes
GerritPathuis 0:de08120b71bd 111
GerritPathuis 0:de08120b71bd 112 // Now analyse register 0x01 ----------------------------------------------
GerritPathuis 0:de08120b71bd 113 ocf_done= off_data[1] & 0x08; // mask off bits, 1= done
GerritPathuis 2:dc991201ff3c 114 if (ocf_done== 0) return(0); // return(0)= compensation process is pending
GerritPathuis 2:dc991201ff3c 115 else return(1); // return(1)= compensation process is completed
GerritPathuis 0:de08120b71bd 116 }
GerritPathuis 0:de08120b71bd 117
GerritPathuis 0:de08120b71bd 118
GerritPathuis 0:de08120b71bd 119 void read_field()
GerritPathuis 0:de08120b71bd 120 {
GerritPathuis 0:de08120b71bd 121 int adr=0;
GerritPathuis 0:de08120b71bd 122 char rx_data[2];
GerritPathuis 0:de08120b71bd 123 int rresult=0;
GerritPathuis 0:de08120b71bd 124 char lsb, msb;
GerritPathuis 0:de08120b71bd 125 unsigned int value;
GerritPathuis 0:de08120b71bd 126
GerritPathuis 0:de08120b71bd 127 // First, now Write pointer to register 0x00----------------------------
GerritPathuis 0:de08120b71bd 128 adr= (i2c_slave_addr1 << 1); // AS5510 address lsb= 0 for write
GerritPathuis 0:de08120b71bd 129 rresult= i2c.write(adr, 0x00, 1, 0); // write one byte to register 0x00 for magnetic field strength
GerritPathuis 0:de08120b71bd 130 if (rresult != 0) pc.printf("No ACK bit! (22)\n\r");
GerritPathuis 0:de08120b71bd 131
GerritPathuis 0:de08120b71bd 132 // Second, now Read register 0x00 and 0x01--------------------------------
GerritPathuis 0:de08120b71bd 133 memset(rx_data, 0, sizeof(rx_data));
GerritPathuis 0:de08120b71bd 134 adr= (i2c_slave_addr1 << 1) | 0x01; // AS5510 address lsb= 1 for read
GerritPathuis 0:de08120b71bd 135 rresult= i2c.read(adr, rx_data, 2, 0); // read two bytes
GerritPathuis 0:de08120b71bd 136
GerritPathuis 0:de08120b71bd 137
GerritPathuis 0:de08120b71bd 138 // Now analyse register 0x01 ----------------------------------------------
GerritPathuis 0:de08120b71bd 139 lsb= rx_data[0]; // get LSB
GerritPathuis 0:de08120b71bd 140 msb= rx_data[1]&0x03; // need only 2 low bits og MSB
GerritPathuis 0:de08120b71bd 141 value = ((msb & 0x03)<<8) + lsb;
GerritPathuis 0:de08120b71bd 142 pc.printf("Magnetic Field => msb= 0x%02X, lsb= 0x%02X, decimal 10-bit value = %u \r\n ", rx_data[0],rx_data[1], value);
GerritPathuis 0:de08120b71bd 143 }
GerritPathuis 0:de08120b71bd 144
GerritPathuis 0:de08120b71bd 145