Example of reading and magnetometer sensor (HMC5883L)
Dependencies: MODSERIAL mbed-rtos mbed
Fork of ReadingMag_HMC5883L by
Diff: HMC5883L.cpp
- Revision:
- 0:6bc5f85ca6fa
diff -r 000000000000 -r 6bc5f85ca6fa HMC5883L.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/HMC5883L.cpp Tue May 21 13:48:10 2013 +0000 @@ -0,0 +1,133 @@ +#include "HMC5883L.h" + +HMC5883L::HMC5883L(PinName sda, PinName scl): i2c(sda, scl) +{ + //100KHz, as specified by the datasheet. + char rx; + + + i2c.frequency(100000); + //Testar depois com 400KHz + //========================================================================================================== + // Read chip_id + //========================================================================================================== + rx = Read(HMC5883L_IDENT_A); + if (rx != 0x48)//ID do chip + printf("\ninvalid chip id %d\r\n", rx); + + //========================================================================================================== + // Let's set the Configuration Register A + //========================================================================================================== + // This register set's the number of samples averaged per measurement output, the rate at which data is written + // to all three data output registers and the measurement flow of the device. + // ------------------------------------------------------- + // |CRA7 CRA6 CRA5 CRA4 CRA3 CRA2 CRA1 CRA0 | + // |(1) MA1(1) MA0(1) DO2(1) DO1(0) DO0(0) MS1(0) MS0(0)| -> This is the default value + // ------------------------------------------------------- + // CRA7 -> we have to clear this bit for correct operation (0) + // CRA6 to CRA5 -> Let's select the maximum number of samples averaged per measurement output (11) + // CRA4 to CRA2 -> Also let's select the maximum data output rate (110) + // CRA1 to CRA0 -> The measurement flow is defined to normal (00) + // ------------------------------------------------------- + // |CRA7 CRA6 CRA5 CRA4 CRA3 CRA2 CRA1 CRA0 | + // |(0) MA1(1) MA0(1) DO2(1) DO1(1) DO0(0) MS1(0) MS0(0)| -> This is the new value, 0x78 in hex + // ------------------------------------------------------- + //Write(HMC5883L_CONFIG_A,0x78); + //Write(HMC5883L_CONFIG_A,0x70); + + //========================================================================================================== + // The Configuration Register B is set to 0010 0000 by default, this is a +/- 1.3 Ga sensor field range and + // the gain of LSB/gauss is 1090. This is the maximum value, so let's leave it like that. + //========================================================================================================== + //Datasheet page 13. I will explain later + //Write(HMC5883L_CONFIG_B,0x20); + //Write(HMC5883L_CONFIG_B,0xA0); + + //========================================================================================================== + // Let's set the Mode Register + //========================================================================================================== + // This register set's the operation mode, from continuous-measurements mode, single-measurement mode and idle mode. + // We will set to Continuouse-measurement mode, so the device continuously performs measurements and places the + // result in the data register + // --------------------------------------------- + // |MR7 MR6 MR5 MR4 MR3 MR2 MR1 MR0 | -> This is the new value, 0x78 in hex, we are going to change + // |(1) (0) (0) (0) (0) (0) MD1(0) MD0(1)| the MD1 and MD0 to 00 and clear the MR7 for correct operation. + // --------------------------------------------- The final value is 0000 0000 (0x00). + Write(HMC5883L_MODE,0x00); +} + + +void HMC5883L::Write(char reg_address, char data) +{ + char tx[2]; + tx[0]=reg_address; + tx[1]=data; + + i2c.write(HMC5883L_I2C_WRITE,tx,2); +} + +char HMC5883L::Read(char data) +{ + char tx = data; + char rx; + + i2c.write(HMC5883L_I2C_WRITE, &tx, 1); + i2c.read(HMC5883L_I2C_READ, &rx, 1); + return rx; +} + +void HMC5883L::MultiByteRead(char address, char* output, int size) +{ + i2c.write(HMC5883L_I2C_WRITE, &address, 1); //tell it where to read from + i2c.read(HMC5883L_I2C_READ, output, size); //tell it where to store the data read +} + +float HMC5883L::getMx() +{ + //return (x * m_Scale); + char lsb_byte = 0; + signed short msb_byte; + + lsb_byte = Read(HMC5883L_X_MSB); + msb_byte = lsb_byte << 8; + msb_byte |= Read(HMC5883L_X_LSB); + return (float)msb_byte; + /* + char tx[1]; + char rx[2]; + + + tx[0]=HMC5883L_X_MSB; + i2c.write(HMC5883L_I2C_READ,tx,1); + i2c.read(HMC5883L_I2C_READ,rx,2); + return ((int)rx[0]<<8|(int)rx[1]); + */ + +} + +float HMC5883L::getMy() +{ + //return (y * m_Scale); + + char lsb_byte = 0; + signed short msb_byte; + + lsb_byte = Read(HMC5883L_Y_MSB); + msb_byte = lsb_byte << 8; + msb_byte |= Read(HMC5883L_Y_LSB); + return (float)msb_byte; +} + + +float HMC5883L::getMz() +{ + //return (z * m_Scale); + + char lsb_byte = 0; + signed short msb_byte; + + lsb_byte = Read(HMC5883L_Z_MSB); + msb_byte = lsb_byte << 8; + msb_byte |= Read(HMC5883L_Z_LSB); + return (float)msb_byte; + } \ No newline at end of file