Kehinde Aina
MMA8452
Dependents: ECE2035_SUM17_Project
Diff: MMA8452.cpp
- Revision:
- 0:79012a2fa4d1
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/MMA8452.cpp Fri Jul 14 21:42:37 2017 +0000
@@ -0,0 +1,538 @@
+// Authors: Ashley Mills, Nicholas Herriot
+/* Copyright (c) 2013 Vodafone, MIT License
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+ * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "MMA8452.h"
+#include "mbed.h"
+
+#ifdef MMA8452_DEBUG
+// you need to define Serial pc(USBTX,USBRX) somewhere for the below line to make sense
+extern Serial pc;
+#define MMA8452_DBG(...) pc.printf(__VA_ARGS__); pc.printf("\r\n");
+#else
+#define MMA8452_DBG(...)
+#endif
+
+// Connect module at I2C address using I2C port pins sda and scl
+MMA8452::MMA8452(PinName sda, PinName scl, int frequency) : _i2c(sda, scl) , _frequency(frequency) {
+ MMA8452_DBG("Creating MMA8452");
+
+ // set I2C frequency
+ _i2c.frequency(_frequency);
+
+ // setup read and write addresses for convenience
+ _readAddress = MMA8452_ADDRESS | 0x01;
+ _writeAddress = MMA8452_ADDRESS & 0xFE;
+
+ // set some defaults
+ _bitDepth = BIT_DEPTH_UNKNOWN;
+ setBitDepth(BIT_DEPTH_12);
+ _dynamicRange = DYNAMIC_RANGE_UNKNOWN;
+ setDynamicRange(DYNAMIC_RANGE_2G);
+
+ MMA8452_DBG("Done");
+}
+
+
+// Destroys instance
+MMA8452::~MMA8452() {}
+
+// Setting the control register bit 1 to true to activate the MMA8452
+int MMA8452::activate() {
+ // perform write and return error code
+ return logicalORRegister(MMA8452_CTRL_REG_1,MMA8452_ACTIVE_MASK);
+}
+
+// Setting the control register bit 1 to 0 to standby the MMA8452
+int MMA8452::standby() {
+ // perform write and return error code
+ return logicalANDRegister(MMA8452_CTRL_REG_1,MMA8452_STANDBY_MASK);
+}
+
+// this reads a register, applies a bitmask with logical AND, sets a value with logical OR,
+// and optionally goes into and out of standby at the beginning and end of the function respectively
+int MMA8452::maskAndApplyRegister(char reg, char mask, char value, int toggleActivation) {
+ if(toggleActivation) {
+ if(standby()) {
+ return 1;
+ }
+ }
+
+ // read from register
+ char oldValue = 0;
+ if(readRegister(reg,&oldValue)) {
+ return 1;
+ }
+
+ // apply bitmask
+ oldValue &= mask;
+
+ // set value
+ oldValue |= value;
+
+ // write back to register
+ if(writeRegister(reg,oldValue)) {
+ return 1;
+ }
+
+ if(toggleActivation) {
+ if(activate()) {
+ return 1;
+ }
+ }
+ return 0;
+}
+
+int MMA8452::setDynamicRange(DynamicRange range, int toggleActivation) {
+ _dynamicRange = range;
+ return maskAndApplyRegister(
+ MMA8452_XYZ_DATA_CFG,
+ MMA8452_DYNAMIC_RANGE_MASK,
+ range,
+ toggleActivation
+ );
+}
+
+int MMA8452::setDataRate(DataRateHz dataRate, int toggleActivation) {
+ return maskAndApplyRegister(
+ MMA8452_CTRL_REG_1,
+ MMA8452_DATA_RATE_MASK,
+ dataRate<<MMA8452_DATA_RATE_MASK_SHIFT,
+ toggleActivation
+ );
+}
+
+int MMA8452::setBitDepth(BitDepth depth,int toggleActivation) {
+ _bitDepth = depth;
+ return maskAndApplyRegister(
+ MMA8452_CTRL_REG_1,
+ MMA8452_BIT_DEPTH_MASK,
+ depth<<MMA8452_BIT_DEPTH_MASK_SHIFT,
+ toggleActivation
+ );
+}
+
+char MMA8452::getMaskedRegister(int addr, char mask) {
+ char rval = 0;
+ if(readRegister(addr,&rval)) {
+ return 0;
+ }
+ return (rval&mask);
+}
+
+int MMA8452::isXYZReady() {
+ return getMaskedRegister(MMA8452_STATUS,MMA8452_STATUS_ZYXDR_MASK)>0;
+}
+
+int MMA8452::isXReady() {
+ return getMaskedRegister(MMA8452_STATUS,MMA8452_STATUS_XDR_MASK)>0;
+}
+
+int MMA8452::isYReady() {
+ return getMaskedRegister(MMA8452_STATUS,MMA8452_STATUS_YDR_MASK)>0;
+}
+
+int MMA8452::isZReady() {
+ return getMaskedRegister(MMA8452_STATUS,MMA8452_STATUS_ZDR_MASK)>0;
+}
+
+
+int MMA8452::getDeviceID(char *dst) {
+ return readRegister(MMA8452_WHO_AM_I,dst);
+}
+
+int MMA8452::getStatus(char* dst) {
+ return readRegister(MMA8452_STATUS,dst);
+}
+
+MMA8452::DynamicRange MMA8452::getDynamicRange() {
+ char rval = 0;
+ if(readRegister(MMA8452_XYZ_DATA_CFG,&rval)) {
+ return MMA8452::DYNAMIC_RANGE_UNKNOWN;
+ }
+ rval &= (MMA8452_DYNAMIC_RANGE_MASK^0xFF);
+ return (MMA8452::DynamicRange)rval;
+}
+
+MMA8452::DataRateHz MMA8452::getDataRate() {
+ char rval = 0;
+ if(readRegister(MMA8452_CTRL_REG_1,&rval)) {
+ return MMA8452::RATE_UNKNOWN;
+ }
+ // logical AND with inverse of mask
+ rval = rval&(MMA8452_DATA_RATE_MASK^0xFF);
+ // shift back into position
+ rval >>= MMA8452_DATA_RATE_MASK_SHIFT;
+ return (MMA8452::DataRateHz)rval;
+}
+
+// Reads xyz
+int MMA8452::readXYZRaw(char *dst) {
+ if(_bitDepth==BIT_DEPTH_UNKNOWN) {
+ return 1;
+ }
+ int readLen = 3;
+ if(_bitDepth==BIT_DEPTH_12) {
+ readLen = 6;
+ }
+ return readRegister(MMA8452_OUT_X_MSB,dst,readLen);
+}
+
+int MMA8452::readXRaw(char *dst) {
+ if(_bitDepth==BIT_DEPTH_UNKNOWN) {
+ return 1;
+ }
+ int readLen = 1;
+ if(_bitDepth==BIT_DEPTH_12) {
+ readLen = 2;
+ }
+ return readRegister(MMA8452_OUT_X_MSB,dst,readLen);
+}
+
+int MMA8452::readYRaw(char *dst) {
+ if(_bitDepth==BIT_DEPTH_UNKNOWN) {
+ return 1;
+ }
+ int readLen = 1;
+ if(_bitDepth==BIT_DEPTH_12) {
+ readLen = 2;
+ }
+ return readRegister(MMA8452_OUT_Y_MSB,dst,readLen);
+}
+
+int MMA8452::readZRaw(char *dst) {
+ if(_bitDepth==BIT_DEPTH_UNKNOWN) {
+ return 1;
+ }
+ int readLen = 1;
+ if(_bitDepth==BIT_DEPTH_12) {
+ readLen = 2;
+ }
+ return readRegister(MMA8452_OUT_Z_MSB,dst,readLen);
+}
+
+int MMA8452::readXYZCounts(int *x, int *y, int *z) {
+ char buf[6];
+ if(readXYZRaw((char*)&buf)) {
+ return 1;
+ }
+ if(_bitDepth==BIT_DEPTH_12) {
+ *x = twelveBitToSigned(&buf[0]);
+ *y = twelveBitToSigned(&buf[2]);
+ *z = twelveBitToSigned(&buf[4]);
+ } else {
+ *x = eightBitToSigned(&buf[0]);
+ *y = eightBitToSigned(&buf[1]);
+ *z = eightBitToSigned(&buf[2]);
+ }
+
+ return 0;
+}
+
+int MMA8452::readXCount(int *x) {
+ char buf[2];
+ if(readXRaw((char*)&buf)) {
+ return 1;
+ }
+ if(_bitDepth==BIT_DEPTH_12) {
+ *x = twelveBitToSigned(&buf[0]);
+ } else {
+ *x = eightBitToSigned(&buf[0]);
+ }
+ return 0;
+}
+
+int MMA8452::readYCount(int *y) {
+ char buf[2];
+ if(readYRaw((char*)&buf)) {
+ return 1;
+ }
+ if(_bitDepth==BIT_DEPTH_12) {
+ *y = twelveBitToSigned(&buf[0]);
+ } else {
+ *y = eightBitToSigned(&buf[0]);
+ }
+ return 0;
+}
+
+int MMA8452::readZCount(int *z) {
+ char buf[2];
+ if(readZRaw((char*)&buf)) {
+ return 1;
+ }
+ if(_bitDepth==BIT_DEPTH_12) {
+ *z = twelveBitToSigned(&buf[0]);
+ } else {
+ *z = eightBitToSigned(&buf[0]);
+ }
+ return 0;
+}
+
+double MMA8452::convertCountToGravity(int count, int countsPerG) {
+ return (double)count/(double)countsPerG;
+}
+
+int MMA8452::getCountsPerG() {
+ // assume starting with DYNAMIC_RANGE_2G and BIT_DEPTH_12
+ int countsPerG = 1024;
+ if(_bitDepth==BIT_DEPTH_8) {
+ countsPerG = 64;
+ }
+ switch(_dynamicRange) {
+ case DYNAMIC_RANGE_4G:
+ countsPerG /= 2;
+ break;
+ case DYNAMIC_RANGE_8G:
+ countsPerG /= 4;
+ break;
+ }
+ return countsPerG;
+}
+
+int MMA8452::readXYZGravity(double *x, double *y, double *z) {
+ int xCount = 0, yCount = 0, zCount = 0;
+ if(readXYZCounts(&xCount,&yCount,&zCount)) {
+ return 1;
+ }
+ int countsPerG = getCountsPerG();
+
+ *x = convertCountToGravity(xCount,countsPerG);
+ *y = convertCountToGravity(yCount,countsPerG);
+ *z = convertCountToGravity(zCount,countsPerG);
+ return 0;
+}
+
+int MMA8452::readXGravity(double *x) {
+ int xCount = 0;
+ if(readXCount(&xCount)) {
+ return 1;
+ }
+ int countsPerG = getCountsPerG();
+
+ *x = convertCountToGravity(xCount,countsPerG);
+ return 0;
+}
+
+int MMA8452::readYGravity(double *y) {
+ int yCount = 0;
+ if(readYCount(&yCount)) {
+ return 1;
+ }
+ int countsPerG = getCountsPerG();
+
+ *y = convertCountToGravity(yCount,countsPerG);
+ return 0;
+}
+
+int MMA8452::readZGravity(double *z) {
+ int zCount = 0;
+ if(readZCount(&zCount)) {
+ return 1;
+ }
+ int countsPerG = getCountsPerG();
+
+ *z = convertCountToGravity(zCount,countsPerG);
+ return 0;
+}
+
+// apply an AND mask to a register. read register value, apply mask, write it back
+int MMA8452::logicalANDRegister(char addr, char mask) {
+ char value = 0;
+ // read register value
+ if(readRegister(addr,&value)) {
+ return 0;
+ }
+ // apply mask
+ value &= mask;
+ return writeRegister(addr,value);
+}
+
+
+// apply an OR mask to a register. read register value, apply mask, write it back
+int MMA8452::logicalORRegister(char addr, char mask) {
+ char value = 0;
+ // read register value
+ if(readRegister(addr,&value)) {
+ return 0;
+ }
+ // apply mask
+ value |= mask;
+ return writeRegister(addr,value);
+}
+
+// apply an OR mask to a register. read register value, apply mask, write it back
+int MMA8452::logicalXORRegister(char addr, char mask) {
+ char value = 0;
+ // read register value
+ if(readRegister(addr,&value)) {
+ return 0;
+ }
+ // apply mask
+ value ^= mask;
+ return writeRegister(addr,value);
+}
+
+// Write register (The device must be placed in Standby Mode to change the value of the registers)
+int MMA8452::writeRegister(char addr, char data) {
+ // what this actually does is the following
+ // 1. tell I2C bus to start transaction
+ // 2. tell slave we want to write (slave address & write flag)
+ // 3. send the write address
+ // 4. send the data to write
+ // 5. tell I2C bus to end transaction
+
+ // we can wrap this up in the I2C library write function
+ char buf[2] = {0,0};
+ buf[0] = addr;
+ buf[1] = data;
+ return _i2c.write(MMA8452_ADDRESS, buf,2);
+ // note, could also do return writeRegister(addr,&data,1);
+}
+
+int MMA8452::eightBitToSigned(char *buf) {
+ return (int8_t)*buf;
+}
+
+int MMA8452::twelveBitToSigned(char *buf) {
+ // cheat by using the int16_t internal type
+ // all we need to do is convert to little-endian format and shift right
+ int16_t x = 0;
+ ((char*)&x)[1] = buf[0];
+ ((char*)&x)[0] = buf[1];
+ // note this only works because the below is an arithmetic right shift
+ return x>>4;
+}
+
+int MMA8452::writeRegister(char addr, char *data, int nbytes) {
+ // writing multiple bytes is a little bit annoying because
+ // the I2C library doesn't support sending the address separately
+ // so we just do it manually
+
+ // 1. tell I2C bus to start transaction
+ _i2c.start();
+ // 2. tell slave we want to write (slave address & write flag)
+ if(_i2c.write(_writeAddress)!=1) {
+ return 1;
+ }
+ // 3. send the write address
+ if(_i2c.write(addr)!=1) {
+ return 1;
+ }
+ // 4. send the data to write
+ for(int i=0; i<nbytes; i++) {
+ if(_i2c.write(data[i])!=1) {
+ return 1;
+ }
+ }
+ // 5. tell I2C bus to end transaction
+ _i2c.stop();
+ return 0;
+}
+
+int MMA8452::readRegister(char addr, char *dst, int nbytes) {
+ // this is a bit odd, but basically proceeds like this
+ // 1. Send a start command
+ // 2. Tell the slave we want to write (slave address & write flag)
+ // 3. Send the address of the register (addr)
+ // 4. Send another start command to delineate read portion
+ // 5. Tell the slave we want to read (slave address & read flag)
+ // 6. Read the register value bytes
+ // 7. Send a stop command
+
+ // we can wrap this process in the I2C library read and write commands
+ if(_i2c.write(MMA8452_ADDRESS,&addr,1,true)) {
+ return 1;
+ }
+ return _i2c.read(MMA8452_ADDRESS,dst,nbytes);
+}
+
+// most registers are 1 byte, so here is a convenience function
+int MMA8452::readRegister(char addr, char *dst) {
+ return readRegister(addr,dst,1);
+}
+
+MMA8452::BitDepth MMA8452::getBitDepth() {
+ return _bitDepth;
+}
+
+#ifdef MMA8452_DEBUG
+void MMA8452::debugRegister(char reg) {
+ // get register value
+ char v = 0;
+ if(readRegister(reg,&v)) {
+ MMA8452_DBG("Error reading specified register");
+ return;
+ }
+ // print out details
+ switch(reg) {
+ case MMA8452_CTRL_REG_1:
+ MMA8452_DBG("CTRL_REG_1 has value: 0x%x",v);
+ MMA8452_DBG(" 7 ALSP_RATE_1: %d",(v&0x80)>>7);
+ MMA8452_DBG(" 6 ALSP_RATE_0: %d",(v&0x40)>>6);
+ MMA8452_DBG(" 5 DR2: %d", (v&0x20)>>5);
+ MMA8452_DBG(" 4 DR1: %d", (v&0x10)>>4);
+ MMA8452_DBG(" 3 DR0: %d", (v&0x08)>>3);
+ MMA8452_DBG(" 2 LNOISE: %d", (v&0x04)>>2);
+ MMA8452_DBG(" 1 FREAD: %d", (v&0x02)>>1);
+ MMA8452_DBG(" 0 ACTIVE: %d", (v&0x01));
+ break;
+
+ case MMA8452_XYZ_DATA_CFG:
+ MMA8452_DBG("XYZ_DATA_CFG has value: 0x%x",v);
+ MMA8452_DBG(" 7 Unused: %d", (v&0x80)>>7);
+ MMA8452_DBG(" 6 0: %d", (v&0x40)>>6);
+ MMA8452_DBG(" 5 0: %d", (v&0x20)>>5);
+ MMA8452_DBG(" 4 HPF_Out: %d",(v&0x10)>>4);
+ MMA8452_DBG(" 3 0: %d", (v&0x08)>>3);
+ MMA8452_DBG(" 2 0: %d", (v&0x04)>>2);
+ MMA8452_DBG(" 1 FS1: %d", (v&0x02)>>1);
+ MMA8452_DBG(" 0 FS0: %d", (v&0x01));
+ switch(v&0x03) {
+ case 0:
+ MMA8452_DBG("Dynamic range: 2G");
+ break;
+ case 1:
+ MMA8452_DBG("Dynamic range: 4G");
+ break;
+ case 2:
+ MMA8452_DBG("Dynamic range: 8G");
+ break;
+ default:
+ MMA8452_DBG("Unknown dynamic range");
+ break;
+ }
+ break;
+
+ case MMA8452_STATUS:
+ MMA8452_DBG("STATUS has value: 0x%x",v);
+ MMA8452_DBG(" 7 ZYXOW: %d",(v&0x80)>>7);
+ MMA8452_DBG(" 6 ZOW: %d", (v&0x40)>>6);
+ MMA8452_DBG(" 5 YOW: %d", (v&0x20)>>5);
+ MMA8452_DBG(" 4 XOW: %d", (v&0x10)>>4);
+ MMA8452_DBG(" 3 ZYXDR: %d",(v&0x08)>>3);
+ MMA8452_DBG(" 2 ZDR: %d", (v&0x04)>>2);
+ MMA8452_DBG(" 1 YDR: %d", (v&0x02)>>1);
+ MMA8452_DBG(" 0 XDR: %d", (v&0x01));
+ break;
+
+ default:
+ MMA8452_DBG("Unknown register address: 0x%x",reg);
+ break;
+ }
+}
+#endif
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