José Claudio
Example of reading an gyroscope sensor (ITG3205)
Diff: ITG3205.cpp
- Revision:
- 0:d884c7453c85
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/ITG3205.cpp Tue May 21 13:50:20 2013 +0000
@@ -0,0 +1,200 @@
+
+#include "ITG3205.h"
+
+ITG3205::ITG3205(PinName sda, PinName scl) : i2c(sda, scl)
+{
+ char rx;
+ //400kHz, fast mode.
+ i2c.frequency(400000);
+ //===========================================================================================================
+ // Read chip_id
+ //===========================================================================================================
+ rx = Read(ITG3205_WHO_AM_I);
+ if (rx != 0x68 && rx!= 0x69) // Data sheet say's "The slave address of the ITG-3205
+ printf("\ninvalid chip id %d\r\n", rx); // devices is b110100X". This could be either, 0x68 or 0x69
+ //===========================================================================================================
+ // Let's reset the chip to it's default configuration
+ //===========================================================================================================
+ // The PWR_MGM (0x3E) is composed of six parameters, to reset is necessary to set the H_RESET (bit 7)
+ // PWR_MGM Register |===============================================|
+ // bits | 7 6 5 4 3 2 1 0 |
+ // | H_RESET SLEEP STBY_XG STBY_YG STBY_ZG CLK_SEL |
+ // | 1 0 0 0 0 0 0 0 |
+ // |===============================================|
+ Write(ITG3205_PWRM, 0x80);
+ //==========================================================================================================
+ // Let's define the low-pass filter's bandwidth to 42Hz (DLPF_CFG<2:0> -> 011) with internal sample rate of
+ // 1kHz, to reduce noise in the signal, and also, let's define the gyro's sensors (FS_SELT<4:3> -> 11) to
+ // FullScale Range (+/- 2000º/sec).
+ // To set the DLPF_CFG bit, we will have to acces the DLP_FS register (0x16)
+ //==========================================================================================================
+ // The DLP_FS is composed of the FS_SEL (Bit 4 and 3) and the DLPF_CFG (Bit 1 and 0)
+ // DPL_FS Register |================================|
+ // bits | 7 6 5 |4 3| |2 1 0| |
+ // | X X X |FS_SEL| |DLPF_CFG| |
+ // | 0 0 0 1 1 0 1 1 | -> (0x1B) Sets the gyro to FullScale Range (+/- 2000º/sec) and Low-Pass Filter
+ // |================================| with bandwidth of 42Hz and internal sample rate of 1kHz.
+ Write(ITG3205_DLPFS, 0x1B);
+ //Let's check
+ rx = Read(ITG3205_DLPFS); // procedure: readed value: i.e XXX1 1110 -> The bits that we want to check are the bits 0,1,2,3 and 4, so we have to eliminate the other bits
+ rx &= (~0xE0); //Mask // (AND) 0001 1111 -> (~DLPFSMask)
+ if(rx != 0x1B) // ---------
+ printf("DPL_FS register has not been written: %d\r\n", rx); // 0001 1110 -> Final value, compare with the wanted value (this one doesn't match)
+ //==========================================================================================================
+ // Now let's define the sample rate to 5msec.
+ // To do this, a formula is applied: Fsample = Finternal/(x+1) on wich Fsample is the inverse o our sample rate,
+ // and Finternal is equal to 1kHz, as defined in the low-pass filter's bandwidth.
+ // The SMPLRT register (0x15) controls the sample rate, so we must set this register to 4, as the result of x in the
+ // equation.
+ //==========================================================================================================
+ /*
+ Write(ITG3205_SMPLRT, 0x04);
+ //Let's check
+ rx = Read(ITG3205_SMPLRT);
+ if(rx != 0x04)
+ printf("SMPLRT register has not been written: %d\r\n", rx);
+ */
+ //==========================================================================================================
+ // Generate interrupt when device is ready or raw data ready
+ //==========================================================================================================
+ // The PWR_MGM is composed of six parameters, to reset is necessary to set the H_RESET (bit 7)
+ // PWR_MGM Register |==========================================================================|
+ // bits | 7 6 5 4 3 2 1 0 |
+ // | ACTL OPEN LATCH_INT_EN INT_ANYRD_2CLEAR 0 ITG_RDY_EN 0 RAW_RDY_EN |
+ // | 0 0 0 0 0 1 0 1 | -> 0x05
+ // |==========================================================================|
+ //Write(ITG3205_INT_CFG, 0x05);
+ Write(ITG3205_INT_CFG, 0x00);
+ //==========================================================================================================
+ // Back the PWR_MGM to what it was
+ //==========================================================================================================
+ Write(ITG3205_PWRM, 0x00);
+}
+
+
+
+void ITG3205::Write(char reg, char data)
+{
+ char c_data[2];
+ c_data[0] = reg;
+ c_data[1] = data;
+ i2c.write((ITG3205_ADDR << 1), c_data, 2);
+}
+
+char ITG3205::Read(char data)
+{
+ char tx = data;
+ char rx;
+
+ i2c.write((ITG3205_ADDR << 1) & 0xFE, &tx, 1); // 0xFE ensure that the MSB bit is being set to zero (RW=0 -> Writing)
+ i2c.read((ITG3205_ADDR << 1) | 0x01, &rx, 1); // 0x01 ensure that the MSB bit is being set to one (RW=1 -> Reading)
+ // The read/write method of I2C does this automatically, so it's useless to set manually
+ return rx;
+}
+/*
+int ITG3205::getInternalSampleRate(void){
+
+ char tx = ITG3205_DLPFS;
+ char rx;
+
+ i2c_.write((ITG3200_I2C_ADDRESS << 1) & 0xFE, &tx, 1);
+
+ i2c_.read((ITG3200_I2C_ADDRESS << 1) | 0x01, &rx, 1);
+
+ //DLPF_CFG == 0 -> sample rate = 8kHz.
+ if(rx == 0){
+ return 8;
+ }
+ //DLPF_CFG = 1..7 -> sample rate = 1kHz.
+ else if(rx >= 1 && rx <= 7){
+ return 1;
+ }
+ //DLPF_CFG = anything else -> something's wrong!
+ else{
+ return -1;
+ }
+
+}
+*/
+bool ITG3205::isRawReady()
+{
+ if(Read(ITG3205_INT_STATUS) == 0x01)
+ return true;
+ else
+ return false;
+
+}
+
+float ITG3205::getGyroX(void)
+{
+ char lsb_byte = 0;
+ signed short msb_byte;
+ float acc;
+
+ lsb_byte = Read(ITG3205_XMSB);
+ msb_byte = lsb_byte << 8;
+ msb_byte |= Read(ITG3205_XLSB);
+ acc = (float)msb_byte;
+ return acc;
+ /*
+ char tx = GYRO_XOUT_H_REG;
+ char rx[2];
+
+ i2c.write((ITG3205_ADDR << 1) & 0xFE, &tx, 1);
+ i2c.read((ITG3205_ADDR << 1) | 0x01, rx, 2);
+
+ int16_t output = ((int) rx[0] << 8) | ((int) rx[1]);
+
+ return output;
+ */
+}
+
+float ITG3205::getGyroY(void)
+{
+ char lsb_byte = 0;
+ signed short msb_byte;
+ float acc;
+
+ lsb_byte = Read(ITG3205_YMSB);
+ msb_byte = lsb_byte << 8;
+ msb_byte |= Read(ITG3205_YLSB);
+ acc = (float)msb_byte;
+ return acc;
+ /*
+ char tx = GYRO_YOUT_H_REG;
+ char rx[2];
+
+ i2c.write((ITG3205_ADDR << 1) & 0xFE, &tx, 1);
+
+ i2c.read((ITG3205_ADDR << 1) | 0x01, rx, 2);
+
+ int16_t output = ((int) rx[0] << 8) | ((int) rx[1]);
+
+ return output;
+ */
+}
+
+float ITG3205::getGyroZ(void)
+{
+ char lsb_byte = 0;
+ signed short msb_byte;
+ float acc;
+
+ lsb_byte = Read(ITG3205_ZMSB);
+ msb_byte = lsb_byte << 8;
+ msb_byte |= Read(ITG3205_ZLSB);
+ acc = (float)msb_byte;
+ return acc;
+ /*
+ char tx = GYRO_ZOUT_H_REG;
+ char rx[2];
+
+ i2c.write((ITG3205_ADDR << 1) & 0xFE, &tx, 1);
+
+ i2c.read((ITG3205_ADDR << 1) | 0x01, rx, 2);
+
+ int16_t output = ((int) rx[0] << 8) | ((int) rx[1]);
+
+ return output;
+ */
+}
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