José Claudio
Example of reading and magnetometer sensor (HMC5883L)
Revision 0:6bc5f85ca6fa, committed 2013-05-21
- Comitter:
- jose_claudiojr
- Date:
- Tue May 21 13:48:10 2013 +0000
- Commit message:
- Example of reading and magnetometer sensor (HMC5883L)
Changed in this revision
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
diff -r 000000000000 -r 6bc5f85ca6fa HMC5883L.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/HMC5883L.h Tue May 21 13:48:10 2013 +0000
@@ -0,0 +1,41 @@
+#ifndef HMC5883L_H
+#define HMC5883L_H
+
+#include "mbed.h"
+
+#define HMC5883L_IDENT_A 0x0A // In this case the identification register A is used to identify the devide. ASCII value H
+#define HMC5883L_I2C 0x1E // 7-bit address. 0x3C write, 0x3D read.
+#define HMC5883L_I2C_WRITE 0x3C // Same as (& 0xFE), ensure that the MSB bit is being set to zero (RW=0 -> Writing)
+#define HMC5883L_I2C_READ 0x3D // Same as (| 0x01), ensure that the MSB bit is being set to one (RW=1 -> Reading)
+
+#define HMC5883L_CONFIG_A 0x00
+#define HMC5883L_CONFIG_B 0x01
+#define HMC5883L_MODE 0x02
+#define HMC5883L_STATUS 0x09
+
+#define HMC5883L_X_MSB 0x03
+#define HMC5883L_X_LSB 0x04
+#define HMC5883L_Z_MSB 0x05
+#define HMC5883L_Z_LSB 0x06
+#define HMC5883L_Y_MSB 0x07
+#define HMC5883L_Y_LSB 0x08
+
+
+class HMC5883L
+{
+
+public:
+
+ HMC5883L(PinName sda, PinName scl);
+ float getMx();
+ float getMy();
+ float getMz();
+private:
+ void Write(char reg_address, char data);
+ char Read(char data);
+ void MultiByteRead(char address, char* output, int size);
+ I2C i2c;
+
+};
+
+#endif /* HMC5883L_H */
\ No newline at end of file
diff -r 000000000000 -r 6bc5f85ca6fa main.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Tue May 21 13:48:10 2013 +0000
@@ -0,0 +1,69 @@
+#include "mbed.h"
+#include "HMC5883L.h"
+
+#include <math.h>
+
+#define SDA p9
+#define SCL p10
+#define PI 3.14159265
+
+int main()
+{
+ float x, y, z, heading;
+ /*
+ float m_x, m_y, m_z;
+ */
+ printf("Inicializing...\r\n");
+ HMC5883L hmc5883l(SDA, SCL);
+ //HMC5883L *hmc5883l = new HMC5883L(SDA, SCL);
+ printf("OK...\r\n");
+ /*
+ for (int i = 0 ; i < 100 ; i++)
+ {
+ x += hmc5883l.getMx()/100;
+ y += hmc5883l.getMy()/100;
+ z += hmc5883l.getMz()/100;
+ wait_ms(100);
+ }
+
+
+ m_x = x/2;
+ m_y = y/2;
+ m_z = z/2;
+ */
+ wait(1);
+
+ while(1)
+ {
+ /*
+ x = m_x - hmc5883l.getMx()*0.92;
+ y = m_y - hmc5883l.getMy()*0.92;
+ z = m_z - hmc5883l.getMz()*0.92;
+ */
+ x = hmc5883l.getMx();
+ y = hmc5883l.getMy();
+ z = hmc5883l.getMz();
+
+ heading = atan2(y, x);
+ if(heading < 0)
+ heading += 2*PI;
+ if(heading > 2*PI)
+ heading -= 2*PI;
+
+ heading = heading * 180 / PI;
+
+ // Correct for when signs are reversed.
+ //if(heading < 0)
+ // heading += 2*PI;
+ //if(heading > 2*PI)
+ // heading -= 2*PI;
+
+ //while(heading < 0) heading += 360;
+ //while(heading > 360) heading -= 360;
+
+
+ printf("x: %f \t\ty: %f \t\t z: %f \t\t heading: %f \t\r\n", x, y, z, heading);
+ wait_ms(200);
+
+ }
+}
diff -r 000000000000 -r 6bc5f85ca6fa mbed.bld --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Tue May 21 13:48:10 2013 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/5e5da4a5990b \ No newline at end of file