Kim GiJeong
I2C example
Diff: main.cpp
- Revision:
- 0:98e1e23e4a54
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Mon Aug 12 09:03:49 2019 +0000
@@ -0,0 +1,160 @@
+#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);
+}
+
+