Grant Phillips / LIS3DSH

Class library for a LIS3DSH MEMS digital output motion sensor (acceleromoter).

Dependents:   stm32f407 mbed_blinky STM32F407

LIS3DSH.cpp@5:e6a312714223, 2016-08-09 (annotated)

Committer:
grantphillips
Date:
Tue Aug 09 13:45:18 2016 +0000
Revision:
5:e6a312714223
Parent:
0:36febce4f85e 
Updated comments

Who changed what in which revision?

UserRevisionLine numberNew contents of line
grantphillips 0:36febce4f85e 1 #include "LIS3DSH.h"
grantphillips 0:36febce4f85e 2 #include "mbed.h"
grantphillips 0:36febce4f85e 3
grantphillips 0:36febce4f85e 4 #define LIS3DSH_INFO1 0x0D
grantphillips 0:36febce4f85e 5 #define LIS3DSH_INFO2 0x0E
grantphillips 0:36febce4f85e 6 #define LIS3DSH_WHO_AM_I 0x0F
grantphillips 0:36febce4f85e 7 #define LIS3DSH_OFF_X 0x10
grantphillips 0:36febce4f85e 8 #define LIS3DSH_OFF_Y 0x11
grantphillips 0:36febce4f85e 9 #define LIS3DSH_OFF_Z 0x12
grantphillips 0:36febce4f85e 10 #define LIS3DSH_CTRL_REG4 0x20
grantphillips 0:36febce4f85e 11 #define LIS3DSH_CTRL_REG1 0x21
grantphillips 0:36febce4f85e 12 #define LIS3DSH_CTRL_REG2 0x22
grantphillips 0:36febce4f85e 13 #define LIS3DSH_CTRL_REG3 0x23
grantphillips 0:36febce4f85e 14 #define LIS3DSH_CTRL_REG5 0x24
grantphillips 0:36febce4f85e 15 #define LIS3DSH_CTRL_REG6 0x25
grantphillips 0:36febce4f85e 16 #define LIS3DSH_OUT_X_L 0x28
grantphillips 0:36febce4f85e 17 #define LIS3DSH_OUT_X_H 0x29
grantphillips 0:36febce4f85e 18 #define LIS3DSH_OUT_Y_L 0x2A
grantphillips 0:36febce4f85e 19 #define LIS3DSH_OUT_Y_H 0x2B
grantphillips 0:36febce4f85e 20 #define LIS3DSH_OUT_Z_L 0x2C
grantphillips 0:36febce4f85e 21 #define LIS3DSH_OUT_Z_H 0x2D
grantphillips 0:36febce4f85e 22 #define LIS3DSH_FIFO_CTRL_REG 0x2E
grantphillips 0:36febce4f85e 23
grantphillips 0:36febce4f85e 24 #define LIS3DSH_READ 0x80
grantphillips 0:36febce4f85e 25 #define LIS3DSH_WRITE 0x00
grantphillips 0:36febce4f85e 26
grantphillips 0:36febce4f85e 27 LIS3DSH::LIS3DSH(PinName mosi, PinName miso, PinName clk, PinName cs)
grantphillips 0:36febce4f85e 28 : _spi(mosi, miso, clk), _cs(cs) {
grantphillips 0:36febce4f85e 29
grantphillips 0:36febce4f85e 30 // Make sure CS is high
grantphillips 0:36febce4f85e 31 _cs = 1;
grantphillips 0:36febce4f85e 32
grantphillips 0:36febce4f85e 33 // Set up the spi interface
grantphillips 0:36febce4f85e 34 _spi.format(8, 3);
grantphillips 0:36febce4f85e 35 _spi.frequency(1000000);
grantphillips 0:36febce4f85e 36
grantphillips 0:36febce4f85e 37 // Configure LIS3DSH
grantphillips 0:36febce4f85e 38 WriteReg(LIS3DSH_CTRL_REG4, 0x5F); // Normal power mode, all axes enabled, 50 Hz ODR
grantphillips 0:36febce4f85e 39 WriteReg(LIS3DSH_CTRL_REG5, 0x80); // 200 Hz antialias filter, +/- 2g FS range
grantphillips 0:36febce4f85e 40 WriteReg(LIS3DSH_FIFO_CTRL_REG, 0); // configure FIFO for bypass mode
grantphillips 0:36febce4f85e 41 WriteReg(LIS3DSH_CTRL_REG6, 0x10); // disable FIFO, enable register address auto-increment
grantphillips 0:36febce4f85e 42
grantphillips 0:36febce4f85e 43 /* these two lines prevents lock-up of sampling according to:
grantphillips 0:36febce4f85e 44 https://my.st.com/public/STe2ecommunities/mems_sensors/Lists/Accelerometers/DispForm.aspx?ID=304&Source=/public/STe2ecommunities/mems_sensors/Tags.aspx?tags=sampling
grantphillips 0:36febce4f85e 45
grantphillips 0:36febce4f85e 46 Not sure why it works
grantphillips 0:36febce4f85e 47 */
grantphillips 0:36febce4f85e 48 WriteReg(LIS3DSH_CTRL_REG4, 0x00);
grantphillips 0:36febce4f85e 49 WriteReg(LIS3DSH_CTRL_REG4, 0x37);
grantphillips 0:36febce4f85e 50 }
grantphillips 0:36febce4f85e 51
grantphillips 0:36febce4f85e 52 void LIS3DSH::WriteReg(uint8_t addr, uint8_t data) {
grantphillips 0:36febce4f85e 53 _cs = 0;
grantphillips 0:36febce4f85e 54 _spi.write(LIS3DSH_WRITE | addr);
grantphillips 0:36febce4f85e 55 _spi.write(data);
grantphillips 0:36febce4f85e 56 _cs = 1;
grantphillips 0:36febce4f85e 57 }
grantphillips 0:36febce4f85e 58
grantphillips 0:36febce4f85e 59 uint8_t LIS3DSH::ReadReg(uint8_t addr) {
grantphillips 0:36febce4f85e 60 uint8_t data;
grantphillips 0:36febce4f85e 61
grantphillips 0:36febce4f85e 62 _cs = 0;
grantphillips 0:36febce4f85e 63 _spi.write(LIS3DSH_READ | addr);
grantphillips 0:36febce4f85e 64 data = _spi.write(0x00);
grantphillips 0:36febce4f85e 65 _cs = 1;
grantphillips 0:36febce4f85e 66
grantphillips 0:36febce4f85e 67 return(data);
grantphillips 0:36febce4f85e 68 }
grantphillips 0:36febce4f85e 69
grantphillips 0:36febce4f85e 70 int LIS3DSH::Detect(void) {
grantphillips 0:36febce4f85e 71 if(ReadReg(LIS3DSH_WHO_AM_I) == 0x3F)
grantphillips 0:36febce4f85e 72 return(1);
grantphillips 0:36febce4f85e 73 else
grantphillips 0:36febce4f85e 74 return(0);
grantphillips 0:36febce4f85e 75 }
grantphillips 0:36febce4f85e 76
grantphillips 0:36febce4f85e 77 void LIS3DSH::ReadData(int16_t *X, int16_t *Y, int16_t *Z) {
grantphillips 0:36febce4f85e 78 uint8_t xLSB=0, xMSB, yLSB, yMSB, zLSB, zMSB; // 8-bit values from accelerometer
grantphillips 0:36febce4f85e 79
grantphillips 0:36febce4f85e 80 xMSB = ReadReg(LIS3DSH_OUT_X_H); // read X high byte register
grantphillips 0:36febce4f85e 81 xLSB = ReadReg(LIS3DSH_OUT_X_L); // read X low byte register
grantphillips 0:36febce4f85e 82 yMSB = ReadReg(LIS3DSH_OUT_Y_H);
grantphillips 0:36febce4f85e 83 yLSB = ReadReg(LIS3DSH_OUT_Y_L);
grantphillips 0:36febce4f85e 84 zMSB = ReadReg(LIS3DSH_OUT_Z_H);
grantphillips 0:36febce4f85e 85 zLSB = ReadReg(LIS3DSH_OUT_Z_L);
grantphillips 0:36febce4f85e 86
grantphillips 0:36febce4f85e 87 //pack MSB and LSB bytes for X, Y, and Z
grantphillips 0:36febce4f85e 88 *X = (xMSB << 8) | (xLSB);
grantphillips 0:36febce4f85e 89 *Y = (yMSB << 8) | (yLSB);
grantphillips 0:36febce4f85e 90 *Z = (zMSB << 8) | (zLSB);
grantphillips 0:36febce4f85e 91 }
grantphillips 0:36febce4f85e 92
grantphillips 0:36febce4f85e 93 void LIS3DSH::ReadAngles(float *Roll, float *Pitch) {
grantphillips 0:36febce4f85e 94 int16_t Xg, Yg, Zg; // 16-bit values from accelerometer
grantphillips 0:36febce4f85e 95
grantphillips 0:36febce4f85e 96 //Read X, Y, Z raw values from acceleromoter
grantphillips 0:36febce4f85e 97 ReadData(&Xg, &Yg, &Zg);
grantphillips 0:36febce4f85e 98
grantphillips 0:36febce4f85e 99 //Convert X, Y, and Z accelerometer values to meters per second squared
grantphillips 0:36febce4f85e 100 Xg /= -141;
grantphillips 0:36febce4f85e 101 Zg /= -141;
grantphillips 0:36febce4f85e 102 Yg /= -141;
grantphillips 0:36febce4f85e 103
grantphillips 0:36febce4f85e 104 *Roll = gToDegrees(Zg, Xg); // get degrees between Z and X planes
grantphillips 0:36febce4f85e 105 *Pitch = gToDegrees(Zg, Yg); // get degrees between Z and Y planes
grantphillips 0:36febce4f85e 106 }
grantphillips 0:36febce4f85e 107
grantphillips 0:36febce4f85e 108 float LIS3DSH::gToDegrees(float V, float H)
grantphillips 0:36febce4f85e 109 {
grantphillips 0:36febce4f85e 110 float retval;
grantphillips 0:36febce4f85e 111 uint16_t orientation=0;
grantphillips 0:36febce4f85e 112
grantphillips 0:36febce4f85e 113 if (H == 0) H = 0.001; // preventing division by zero
grantphillips 0:36febce4f85e 114 if (V == 0) V = 0.001; // preventing division by zero
grantphillips 0:36febce4f85e 115
grantphillips 0:36febce4f85e 116 if ((H > 0) && (V > 0)) orientation = 0;
grantphillips 0:36febce4f85e 117 if ((H < 0) && (V > 0)) orientation = 90;
grantphillips 0:36febce4f85e 118 if ((H < 0) && (V < 0)) orientation = 180;
grantphillips 0:36febce4f85e 119 if ((H > 0) && (V < 0)) orientation = 270;
grantphillips 0:36febce4f85e 120
grantphillips 0:36febce4f85e 121 retval = (atan((double)V/(double)H)/3.14159)*180.0;
grantphillips 0:36febce4f85e 122 if ((double)retval < 0)
grantphillips 0:36febce4f85e 123 retval = (double)retval + 90.0;
grantphillips 0:36febce4f85e 124 retval = fabs(retval) + orientation;
grantphillips 0:36febce4f85e 125 return retval;
grantphillips 0:36febce4f85e 126 }