Kim GiJeong
/
try7_i2c
I2C example
main.cpp
- Committer:
- GiJeongKim
- Date:
- 2019-08-12
- Revision:
- 0:98e1e23e4a54
File content as of revision 0:98e1e23e4a54:
#include "mbed.h" ////////////////////////////////////////////////// // Testing AS5510 sensor with K22F // // test results are sent to Tera Term // // I2C frequency set @ 400kHz // // // // Note 1) // // I2C address 0x1C is used by FXOS8700CQ // // 3-axis accelerometer and 3-axis magetometer // // // // Note 2) // // Without magnet present the AS5510 sensor is // // expected to output a value of approx 511 // // (1023/2= 511 // // // // Note 3) // // Lateral Movement of a simple 2-pole magnet. // // Magnet size diameter 1mm length 2mm // // Distance to sensor approx 0.8mm // // Output 10bit resolution // ////////////////////////////////////////////////// Serial pc(USBTX, USBRX); // tx, rx I2C i2c(PC_9,PA_8); // SDA, SCL (for K22F) AnalogOut dac(PA_4); unsigned int value; const int i2c_slave_addr1 = 0x56; // sensor AS5510 number 1 (7 bits), 0x56 or 0x57 DigitalOut check(PC_3); //--- public functions--- void init_as5510(int); void read_field(int); int offset_comp(int); void look_for_hardware_i2c(void); int main() { i2c.frequency(400 * 1000); // 0.4 mHz wait_ms(2); // Power Up wait look_for_hardware_i2c(); // Hardware present ? init_as5510(i2c_slave_addr1); // Initialize // //----------Setup register---------------------- // while (!offset_comp(i2c_slave_addr1)); // while (!offset_comp(i2c_slave_addr2)); // pc.printf("Offset compensation process is completed \r\n"); //----------Get the results---------------------- // flipper.attach(&flip, 0.0002f); while (true) { check=1; read_field(i2c_slave_addr1); // Read magnetic Field sensor #1 check=0; wait(0.005f); dac=(float) value/1024.0; pc.printf("%d\n",value); } } void look_for_hardware_i2c() { pc.printf("\r\n\n\n"); pc.printf("Note I2C address 0x1C used by FXOS8700CQ 3-axis accelerometer and 3-axis magetometer\r\n"); pc.printf("Start hardware search..... \r\n"); int count = 0; for (int address=12; address<256; address+=2) { if (!i2c.write(address, NULL, 0)) { // 0 returned is OK pc.printf(" - I2C device found at address 0x%02X\n\r", address >>1); count++; } } pc.printf("%d devices found \n\r", count); } void init_as5510(int i2c_address) { int i2c_adrs=0; char idata[2]; int result=0; pc.printf("\r\n"); pc.printf("Start AS5510 init.. \r\n"); i2c_adrs= (i2c_address << 1); // AS5510 Slave address lsb= 0 for write //---------- Magnet selection -------------------------------- //----0x00= <50mT-----------Strong magnet //----0x01= <25mT //----0x02= <18.7mT //----0x03= <12.5mT---------Weak magnet //----------------------------------------------------------- idata[0]=0x0B; // Register for Sensitivity idata[1]=0x00; // Byte result= i2c.write(i2c_adrs, idata, 2, 0); // Now write_sensitivity if (result != 0) pc.printf("No ACK bit! (09)\n\r"); //----------- Operation mode selection------------------------ idata[0]=0x02; // 0x02 address setup register for operation, speed, polarity idata[1]=0x04; // Normal Operation, Slow mode (1), NORMAL Polarity (0), Power Up (0) result= i2c.write(i2c_adrs, idata, 2, 0); // Now write_operation if (result != 0) pc.printf("No ACK bit! (11)\n\r"); pc.printf("AS5510 init done\r\n"); } int offset_comp(int i2c_address) { int adrss=0; int oresult=0; char off_data[2]; int ocf_done=0; // First, now Write pointer to register 0x00---------------------------- adrss= (i2c_address << 1); // AS5510 Slave address lsb= 0 for write oresult= i2c.write(adrss, 0x00, 1, 0); // write one byte if (oresult != 0) pc.printf("No ACK bit! (33)\n\r"); // Second, now Read register 0x00 and 0x01-------------------------------- memset(off_data, 0, sizeof(off_data)); adrss= (i2c_address << 1) | 0x01; // AS5510 address lsb= 1 for read oresult= i2c.read(adrss, off_data, 2, 0); // read two bytes // Now analyse register 0x01 ---------------------------------------------- ocf_done= off_data[1] & 0x08; // mask off bits, 1= done if (ocf_done== 0) return(0); // return(0)= compensation process is pending else return(1); // return(1)= compensation process is completed } void read_field(int i2c_address) { int adr=0; char rx_data[2]; int rresult=0; char lsb, msb; // First, now Write pointer to register 0x00---------------------------- adr= (i2c_address << 1); // AS5510 address lsb= 0 for write rresult= i2c.write(adr, 0x00, 1, 0); // write one byte to register 0x00 for magnetic field strength // if (rresult != 0) pc.printf("No ACK bit! (22)\n\r"); // Second, now Read register 0x00 and 0x01-------------------------------- // memset(rx_data, 0, sizeof(rx_data)); adr= (i2c_address << 1) | 0x01; // AS5510 address lsb= 1 for read rresult= i2c.read(adr, rx_data, 2, 0); // read two bytes // Now analyse register 0x01 ---------------------------------------------- lsb= rx_data[0]; // get LSB msb= rx_data[1]&0x03; // need only 2 low bits og MSB value = ((msb & 0x03)<<8) + lsb; // 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); }