Kim GiJeong / Mbed 2 deprecated try7_i2c

I2C example

Dependencies:   mbed

main.cpp@0:98e1e23e4a54, 2019-08-12 (annotated)

Committer:
GiJeongKim
Date:
Mon Aug 12 09:03:49 2019 +0000
Revision:
0:98e1e23e4a54
I2C example;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
GiJeongKim 0:98e1e23e4a54 1 #include "mbed.h"
GiJeongKim 0:98e1e23e4a54 2 //////////////////////////////////////////////////
GiJeongKim 0:98e1e23e4a54 3 // Testing AS5510 sensor with K22F //
GiJeongKim 0:98e1e23e4a54 4 // test results are sent to Tera Term //
GiJeongKim 0:98e1e23e4a54 5 // I2C frequency set @ 400kHz //
GiJeongKim 0:98e1e23e4a54 6 // //
GiJeongKim 0:98e1e23e4a54 7 // Note 1) //
GiJeongKim 0:98e1e23e4a54 8 // I2C address 0x1C is used by FXOS8700CQ //
GiJeongKim 0:98e1e23e4a54 9 // 3-axis accelerometer and 3-axis magetometer //
GiJeongKim 0:98e1e23e4a54 10 // //
GiJeongKim 0:98e1e23e4a54 11 // Note 2) //
GiJeongKim 0:98e1e23e4a54 12 // Without magnet present the AS5510 sensor is //
GiJeongKim 0:98e1e23e4a54 13 // expected to output a value of approx 511 //
GiJeongKim 0:98e1e23e4a54 14 // (1023/2= 511 //
GiJeongKim 0:98e1e23e4a54 15 // //
GiJeongKim 0:98e1e23e4a54 16 // Note 3) //
GiJeongKim 0:98e1e23e4a54 17 // Lateral Movement of a simple 2-pole magnet. //
GiJeongKim 0:98e1e23e4a54 18 // Magnet size diameter 1mm length 2mm //
GiJeongKim 0:98e1e23e4a54 19 // Distance to sensor approx 0.8mm //
GiJeongKim 0:98e1e23e4a54 20 // Output 10bit resolution //
GiJeongKim 0:98e1e23e4a54 21 //////////////////////////////////////////////////
GiJeongKim 0:98e1e23e4a54 22
GiJeongKim 0:98e1e23e4a54 23 Serial pc(USBTX, USBRX); // tx, rx
GiJeongKim 0:98e1e23e4a54 24 I2C i2c(PC_9,PA_8); // SDA, SCL (for K22F)
GiJeongKim 0:98e1e23e4a54 25 AnalogOut dac(PA_4);
GiJeongKim 0:98e1e23e4a54 26 unsigned int value;
GiJeongKim 0:98e1e23e4a54 27
GiJeongKim 0:98e1e23e4a54 28 const int i2c_slave_addr1 = 0x56; // sensor AS5510 number 1 (7 bits), 0x56 or 0x57
GiJeongKim 0:98e1e23e4a54 29 DigitalOut check(PC_3);
GiJeongKim 0:98e1e23e4a54 30
GiJeongKim 0:98e1e23e4a54 31 //--- public functions---
GiJeongKim 0:98e1e23e4a54 32 void init_as5510(int);
GiJeongKim 0:98e1e23e4a54 33 void read_field(int);
GiJeongKim 0:98e1e23e4a54 34 int offset_comp(int);
GiJeongKim 0:98e1e23e4a54 35 void look_for_hardware_i2c(void);
GiJeongKim 0:98e1e23e4a54 36
GiJeongKim 0:98e1e23e4a54 37
GiJeongKim 0:98e1e23e4a54 38 int main()
GiJeongKim 0:98e1e23e4a54 39 {
GiJeongKim 0:98e1e23e4a54 40 i2c.frequency(400 * 1000); // 0.4 mHz
GiJeongKim 0:98e1e23e4a54 41 wait_ms(2); // Power Up wait
GiJeongKim 0:98e1e23e4a54 42
GiJeongKim 0:98e1e23e4a54 43 look_for_hardware_i2c(); // Hardware present ?
GiJeongKim 0:98e1e23e4a54 44 init_as5510(i2c_slave_addr1); // Initialize
GiJeongKim 0:98e1e23e4a54 45 // //----------Setup register----------------------
GiJeongKim 0:98e1e23e4a54 46 // while (!offset_comp(i2c_slave_addr1));
GiJeongKim 0:98e1e23e4a54 47 // while (!offset_comp(i2c_slave_addr2));
GiJeongKim 0:98e1e23e4a54 48 // pc.printf("Offset compensation process is completed \r\n");
GiJeongKim 0:98e1e23e4a54 49
GiJeongKim 0:98e1e23e4a54 50 //----------Get the results----------------------
GiJeongKim 0:98e1e23e4a54 51 // flipper.attach(&flip, 0.0002f);
GiJeongKim 0:98e1e23e4a54 52 while (true) {
GiJeongKim 0:98e1e23e4a54 53 check=1;
GiJeongKim 0:98e1e23e4a54 54 read_field(i2c_slave_addr1); // Read magnetic Field sensor #1
GiJeongKim 0:98e1e23e4a54 55 check=0;
GiJeongKim 0:98e1e23e4a54 56 wait(0.005f);
GiJeongKim 0:98e1e23e4a54 57 dac=(float) value/1024.0;
GiJeongKim 0:98e1e23e4a54 58 pc.printf("%d\n",value);
GiJeongKim 0:98e1e23e4a54 59 }
GiJeongKim 0:98e1e23e4a54 60 }
GiJeongKim 0:98e1e23e4a54 61
GiJeongKim 0:98e1e23e4a54 62
GiJeongKim 0:98e1e23e4a54 63 void look_for_hardware_i2c()
GiJeongKim 0:98e1e23e4a54 64 {
GiJeongKim 0:98e1e23e4a54 65 pc.printf("\r\n\n\n");
GiJeongKim 0:98e1e23e4a54 66 pc.printf("Note I2C address 0x1C used by FXOS8700CQ 3-axis accelerometer and 3-axis magetometer\r\n");
GiJeongKim 0:98e1e23e4a54 67 pc.printf("Start hardware search..... \r\n");
GiJeongKim 0:98e1e23e4a54 68
GiJeongKim 0:98e1e23e4a54 69 int count = 0;
GiJeongKim 0:98e1e23e4a54 70 for (int address=12; address<256; address+=2) {
GiJeongKim 0:98e1e23e4a54 71 if (!i2c.write(address, NULL, 0)) { // 0 returned is OK
GiJeongKim 0:98e1e23e4a54 72 pc.printf(" - I2C device found at address 0x%02X\n\r", address >>1);
GiJeongKim 0:98e1e23e4a54 73 count++;
GiJeongKim 0:98e1e23e4a54 74 }
GiJeongKim 0:98e1e23e4a54 75 }
GiJeongKim 0:98e1e23e4a54 76 pc.printf("%d devices found \n\r", count);
GiJeongKim 0:98e1e23e4a54 77 }
GiJeongKim 0:98e1e23e4a54 78
GiJeongKim 0:98e1e23e4a54 79 void init_as5510(int i2c_address)
GiJeongKim 0:98e1e23e4a54 80 {
GiJeongKim 0:98e1e23e4a54 81 int i2c_adrs=0;
GiJeongKim 0:98e1e23e4a54 82 char idata[2];
GiJeongKim 0:98e1e23e4a54 83 int result=0;
GiJeongKim 0:98e1e23e4a54 84
GiJeongKim 0:98e1e23e4a54 85 pc.printf("\r\n");
GiJeongKim 0:98e1e23e4a54 86 pc.printf("Start AS5510 init.. \r\n");
GiJeongKim 0:98e1e23e4a54 87
GiJeongKim 0:98e1e23e4a54 88 i2c_adrs= (i2c_address << 1); // AS5510 Slave address lsb= 0 for write
GiJeongKim 0:98e1e23e4a54 89
GiJeongKim 0:98e1e23e4a54 90 //---------- Magnet selection --------------------------------
GiJeongKim 0:98e1e23e4a54 91 //----0x00= <50mT-----------Strong magnet
GiJeongKim 0:98e1e23e4a54 92 //----0x01= <25mT
GiJeongKim 0:98e1e23e4a54 93 //----0x02= <18.7mT
GiJeongKim 0:98e1e23e4a54 94 //----0x03= <12.5mT---------Weak magnet
GiJeongKim 0:98e1e23e4a54 95 //-----------------------------------------------------------
GiJeongKim 0:98e1e23e4a54 96 idata[0]=0x0B; // Register for Sensitivity
GiJeongKim 0:98e1e23e4a54 97 idata[1]=0x00; // Byte
GiJeongKim 0:98e1e23e4a54 98 result= i2c.write(i2c_adrs, idata, 2, 0); // Now write_sensitivity
GiJeongKim 0:98e1e23e4a54 99 if (result != 0) pc.printf("No ACK bit! (09)\n\r");
GiJeongKim 0:98e1e23e4a54 100
GiJeongKim 0:98e1e23e4a54 101 //----------- Operation mode selection------------------------
GiJeongKim 0:98e1e23e4a54 102 idata[0]=0x02; // 0x02 address setup register for operation, speed, polarity
GiJeongKim 0:98e1e23e4a54 103 idata[1]=0x04; // Normal Operation, Slow mode (1), NORMAL Polarity (0), Power Up (0)
GiJeongKim 0:98e1e23e4a54 104 result= i2c.write(i2c_adrs, idata, 2, 0); // Now write_operation
GiJeongKim 0:98e1e23e4a54 105 if (result != 0) pc.printf("No ACK bit! (11)\n\r");
GiJeongKim 0:98e1e23e4a54 106
GiJeongKim 0:98e1e23e4a54 107 pc.printf("AS5510 init done\r\n");
GiJeongKim 0:98e1e23e4a54 108 }
GiJeongKim 0:98e1e23e4a54 109
GiJeongKim 0:98e1e23e4a54 110
GiJeongKim 0:98e1e23e4a54 111 int offset_comp(int i2c_address)
GiJeongKim 0:98e1e23e4a54 112 {
GiJeongKim 0:98e1e23e4a54 113 int adrss=0;
GiJeongKim 0:98e1e23e4a54 114 int oresult=0;
GiJeongKim 0:98e1e23e4a54 115 char off_data[2];
GiJeongKim 0:98e1e23e4a54 116 int ocf_done=0;
GiJeongKim 0:98e1e23e4a54 117
GiJeongKim 0:98e1e23e4a54 118 // First, now Write pointer to register 0x00----------------------------
GiJeongKim 0:98e1e23e4a54 119 adrss= (i2c_address << 1); // AS5510 Slave address lsb= 0 for write
GiJeongKim 0:98e1e23e4a54 120 oresult= i2c.write(adrss, 0x00, 1, 0); // write one byte
GiJeongKim 0:98e1e23e4a54 121 if (oresult != 0) pc.printf("No ACK bit! (33)\n\r");
GiJeongKim 0:98e1e23e4a54 122
GiJeongKim 0:98e1e23e4a54 123 // Second, now Read register 0x00 and 0x01--------------------------------
GiJeongKim 0:98e1e23e4a54 124 memset(off_data, 0, sizeof(off_data));
GiJeongKim 0:98e1e23e4a54 125 adrss= (i2c_address << 1) | 0x01; // AS5510 address lsb= 1 for read
GiJeongKim 0:98e1e23e4a54 126 oresult= i2c.read(adrss, off_data, 2, 0); // read two bytes
GiJeongKim 0:98e1e23e4a54 127
GiJeongKim 0:98e1e23e4a54 128 // Now analyse register 0x01 ----------------------------------------------
GiJeongKim 0:98e1e23e4a54 129 ocf_done= off_data[1] & 0x08; // mask off bits, 1= done
GiJeongKim 0:98e1e23e4a54 130 if (ocf_done== 0) return(0); // return(0)= compensation process is pending
GiJeongKim 0:98e1e23e4a54 131 else return(1); // return(1)= compensation process is completed
GiJeongKim 0:98e1e23e4a54 132 }
GiJeongKim 0:98e1e23e4a54 133
GiJeongKim 0:98e1e23e4a54 134
GiJeongKim 0:98e1e23e4a54 135 void read_field(int i2c_address)
GiJeongKim 0:98e1e23e4a54 136 {
GiJeongKim 0:98e1e23e4a54 137 int adr=0;
GiJeongKim 0:98e1e23e4a54 138 char rx_data[2];
GiJeongKim 0:98e1e23e4a54 139 int rresult=0;
GiJeongKim 0:98e1e23e4a54 140 char lsb, msb;
GiJeongKim 0:98e1e23e4a54 141
GiJeongKim 0:98e1e23e4a54 142 // First, now Write pointer to register 0x00----------------------------
GiJeongKim 0:98e1e23e4a54 143 adr= (i2c_address << 1); // AS5510 address lsb= 0 for write
GiJeongKim 0:98e1e23e4a54 144 rresult= i2c.write(adr, 0x00, 1, 0); // write one byte to register 0x00 for magnetic field strength
GiJeongKim 0:98e1e23e4a54 145 // if (rresult != 0) pc.printf("No ACK bit! (22)\n\r");
GiJeongKim 0:98e1e23e4a54 146
GiJeongKim 0:98e1e23e4a54 147 // Second, now Read register 0x00 and 0x01--------------------------------
GiJeongKim 0:98e1e23e4a54 148 // memset(rx_data, 0, sizeof(rx_data));
GiJeongKim 0:98e1e23e4a54 149 adr= (i2c_address << 1) | 0x01; // AS5510 address lsb= 1 for read
GiJeongKim 0:98e1e23e4a54 150 rresult= i2c.read(adr, rx_data, 2, 0); // read two bytes
GiJeongKim 0:98e1e23e4a54 151
GiJeongKim 0:98e1e23e4a54 152
GiJeongKim 0:98e1e23e4a54 153 // Now analyse register 0x01 ----------------------------------------------
GiJeongKim 0:98e1e23e4a54 154 lsb= rx_data[0]; // get LSB
GiJeongKim 0:98e1e23e4a54 155 msb= rx_data[1]&0x03; // need only 2 low bits og MSB
GiJeongKim 0:98e1e23e4a54 156 value = ((msb & 0x03)<<8) + lsb;
GiJeongKim 0:98e1e23e4a54 157 // pc.printf("I2C adres= 0x%02X, Magnetic Field => msb= 0x%02X, lsb= 0x%02X, decimal 10-bit value = %u \r\n ", i2c_address, rx_data[0],rx_data[1], value);
GiJeongKim 0:98e1e23e4a54 158 }
GiJeongKim 0:98e1e23e4a54 159
GiJeongKim 0:98e1e23e4a54 160