yanay nevela
Works with 8g
Fork of
MMA8452
by 
Ashley Mills
Diff: MMA8452.cpp
- Revision:
- 11:dfd1e0afcb7b
- Parent:
- 10:ca9ba7ad4e94
- Child:
- 12:172540ff6b8b
--- a/MMA8452.cpp Tue Mar 04 11:14:34 2014 +0000
+++ b/MMA8452.cpp Tue Mar 04 16:23:40 2014 +0000
@@ -1,4 +1,4 @@
-// Author: Nicholas Herriot
+// Author: Nicholas Herriot, Ashley Mills
/* Copyright (c) 2013 Vodafone, MIT License
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
@@ -17,15 +17,20 @@
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
-# include "MMA8452.h"
+#include "MMA8452.h"
+#include "mbed.h"
+
+extern Serial pc;
// Connect module at I2C address using I2C port pins sda and scl
-MMA8452::MMA8452(PinName sda, PinName scl,int frequency) : m_i2c(sda, scl) , m_frequency(frequency) {
- //m_i2c.frequency(m_frequency);
-
- // setup read and write addresses to avoid duplication
- _readAddress = (MMA8452_ADDRESS<<1) | 0x01;
- _writeAddress = (MMA8452_ADDRESS<<1) & 0xFE;
+MMA8452::MMA8452(PinName sda, PinName scl, int frequency) : _i2c(sda, scl) , _frequency(frequency) {
+ DBG("Creating MMA8452");
+ _i2c.frequency(_frequency);
+
+ // setup read and write addresses to avoid duplication
+ _readAddress = MMA8452_ADDRESS | 0x01;
+ _writeAddress = MMA8452_ADDRESS & 0xFE;
+ DBG("Done");
}
@@ -34,99 +39,93 @@
// Setting the control register bit 1 to true to activate the MMA8452
int MMA8452::activate() {
- // set control register 1 to active
- char init[2] = {CTRL_REG_1,ACTIVE};
-
// perform write and return error code
- return m_i2c.write(_writeAddress,init,2);
+ return logicalORRegister(CTRL_REG_1,MMA8452_ACTIVE_MASK);
}
-
-// Get 'Fast Read Mode' called F_READ. If bit 1 is set '1' then F_READ is active. Fast read will skip LSB when reading xyz
-// resisters from 0x01 to 0x06. When F_READ is '0' then all 6 registers will be read.
-
-int MMA8452::get_CTRL_Reg1(int* dst)
-{
- return readRegister(CTRL_REG_1,dst);
+// Setting the control register bit 1 to 0 to standby the MMA8452
+int MMA8452::standby() {
+ // perform write and return error code
+ return logicalANDRegister(CTRL_REG_1,MMA8452_STANDBY_MASK);
}
-// Setting the control register bit 1 to true to activate the MMA8452
-int MMA8452::standby()
-{
- // set control register 1 to standby
- char init[2] = {CTRL_REG_1,STANDBY};
-
- // write to the register and return the error code
- return m_i2c.write(_writeAddress,init,2);
+// 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;
}
-
-
-// Device initialization
-void MMA8452::init()
-{
-
- writeRegister(INTSU_STATUS, 0x10); // automatic interrupt after every measurement
- writeRegister(SR_STATUS, 0x00); // 120 Samples/Second
- writeRegister(MODE_STATUS, 0x01); // Active Mode
-
+int MMA8452::setDynamicRange(DynamicRange range, int toggleActivation) {
+ return maskAndApplyRegister(
+ MMA8452_XYZ_DATA_CFG,
+ MMA8452_DYNAMIC_RANGE_MASK,
+ range,
+ toggleActivation
+ );
}
-// Get real time status of device - it can be STANDBY, WAKE or SLEEP
-int MMA8452::getSystemMode(int *dst)
-{
- return readRegister(SYSMOD,dst);
+int MMA8452::setDataRate(DataRateHz dataRate, int toggleActivation) {
+ return maskAndApplyRegister(
+ MMA8452_CTRL_REG_1,
+ MMA8452_DATA_RATE_MASK,
+ dataRate<<MMA8452_DATA_RATE_MASK_SHIFT,
+ toggleActivation
+ );
}
-
-
-// Get real time status of device - it can be STANDBY, WAKE or SLEEP
-int MMA8452::getStatus(int* dst)
-{
- return readRegister(STATUS,dst);
+int MMA8452::setBitDepth(BitDepth depth,int toggleActivation) {
+ return maskAndApplyRegister(
+ MMA8452_CTRL_REG_1,
+ MMA8452_BIT_DEPTH_MASK,
+ depth<<MMA8452_BIT_DEPTH_MASK_SHIFT,
+ toggleActivation
+ );
}
// Get device ID
-int MMA8452::getDeviceID(int *dst)
+int MMA8452::getDeviceID(char *dst)
{
return readRegister(WHO_AM_I,dst);
}
-/*
-// Reads x data
-int MMA8452::read_x(int& xaxisLSB)
-{
- char mcu_address = (MMA8452_ADDRESS<<1);
- m_i2c.start();
- if( m_i2c.write( mcu_address & 0xFE) == 0) // just good practice to force bit 1 to a '0' by ANDing with 0xFE
- {
- return 1; // we failed to write the mcu address on the bus to initiate dialogue
- }
- if( m_i2c.write( OUT_X_MSB) == 0)
- {
- return 1; // we failed to write 'X axis LSB' to the chip
- }
- m_i2c.start();
- if( m_i2c.write( mcu_address | 0x01) == 0) // this is asking to read the slave mcu address - even though it's a 'write' method!!! Crap API...
- {
- return 1; // we failed to request a read from that mcu - this really is just writing the mcu vaule on the bus
- }
- xaxisLSB = m_i2c.read(0);
- m_i2c.stop();
- return 0;
-}
-*/
-
int MMA8452::readRaw(char src, char *dst, int len) {
// this is the register we want to get data from
char register_address[1];
register_address[0] = src;
- if(m_i2c.write(_writeAddress,register_address,1,true) == 0)
+ if(_i2c.write(_writeAddress,register_address,1,true) == 0)
{
- if(m_i2c.read(_readAddress,dst,len)==0)
+ if(_i2c.read(_readAddress,dst,len)==0)
{
return 0;
}
@@ -144,8 +143,7 @@
// is set to '0'. It returns '0' success '1' fail. This method does nothing to the registers - just returns
// the raw data.
//int MMA8452::read_x(int& xaxisLSB)
-int MMA8452::readRawX(char *xaxis)
-{
+int MMA8452::readRawX(char *xaxis) {
return readRaw(OUT_X_MSB,xaxis,2);
}
@@ -178,37 +176,57 @@
{
char mcu_address = (MMA8452_ADDRESS <<1);
- m_i2c.start(); // Start
- m_i2c.write(mcu_address); // A write to device 0x98
- m_i2c.write(OUT_Y_MSB); // Register to read
- m_i2c.start();
- m_i2c.write(mcu_address); // Read from device 0x99
- int y = m_i2c.read(0); // Read the data
- m_i2c.stop();
+ _i2c.start(); // Start
+ _i2c.write(mcu_address); // A write to device 0x98
+ _i2c.write(OUT_Y_MSB); // Register to read
+ _i2c.start();
+ _i2c.write(mcu_address); // Read from device 0x99
+ int y = _i2c.read(0); // Read the data
+ _i2c.stop();
return y;
}
-
// Reads z data
int MMA8452::read_z()
{
char mcu_address = (MMA8452_ADDRESS <<1);
- m_i2c.start(); // Start
- m_i2c.write(mcu_address); // A write to device 0x98
- m_i2c.write(OUT_Z_MSB); // Register to read
- m_i2c.start();
- m_i2c.write(mcu_address); // Read from device 0x99
- int z = m_i2c.read(0); // Read the data
- m_i2c.stop();
+ _i2c.start(); // Start
+ _i2c.write(mcu_address); // A write to device 0x98
+ _i2c.write(OUT_Z_MSB); // Register to read
+ _i2c.start();
+ _i2c.write(mcu_address); // Read from device 0x99
+ int z = _i2c.read(0); // Read the data
+ _i2c.stop();
return z;
}
+MMA8452::DynamicRange MMA8452::getDynamicRange() {
+ char rval = 0;
+ if(readRegister(MMA8452_CTRL_REG_1,&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::readRawXYZ(char *x, char *y, char *z)
{
@@ -217,12 +235,12 @@
char mcu_address = (MMA8452_ADDRESS <<1);
char register_buffer[6] ={0,0,0,0,0,0};
const char Addr_X = OUT_X_MSB;
- m_i2c.write(mcu_address); // A write to device 0x98
- m_i2c.write(MMA8452_ADDRESS, &Addr_X, 1); // Pointer to the OUT_X_MSB register
+ _i2c.write(mcu_address); // A write to device 0x98
+ _i2c.write(MMA8452_ADDRESS, &Addr_X, 1); // Pointer to the OUT_X_MSB register
- if(m_i2c.write(mcu_address,&Addr_X,1) == 0)
+ if(_i2c.write(mcu_address,&Addr_X,1) == 0)
{
- if(m_i2c.read(mcu_address,register_buffer,6) == 0)
+ if(_i2c.read(mcu_address,register_buffer,6) == 0)
{
*x = register_buffer[1];
*y = register_buffer[3];
@@ -241,47 +259,159 @@
}
- // Write register (The device must be placed in Standby Mode to change the value of the registers)
-void MMA8452::writeRegister(char addr, char data)
-{
+// 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);
+}
+
- char cmd[2] = {0, 0};
-
- cmd[0] = MODE_STATUS;
- cmd[1] = 0x00; // Standby Mode on
- m_i2c.write(MMA8452_ADDRESS, cmd, 2);
-
- cmd[0] = addr;
- cmd[1] = data; // New value of the register
- m_i2c.write(MMA8452_ADDRESS, cmd, 2);
-
- cmd[0] = MODE_STATUS;
- cmd[1] = 0x01; // Active Mode on
- m_i2c.write(MMA8452_ADDRESS, cmd, 2);
-
+// 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);
}
- // Read from specified MMA7660FC register
-int MMA8452::readRegister(char addr, int *dst)
-{
+
+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
- m_i2c.start();
- if( m_i2c.write(_writeAddress) == 0)
- {
- return 1; // we failed to write the mcu address on the bus to initiate dialogue
+ // 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;
}
- if( m_i2c.write(addr) == 0)
- {
- return 1; // we failed to write 'status' to the chip
- }
- m_i2c.start();
- if( m_i2c.write(_readAddress) == 0) // this is asking to read the slave mcu address - even though it's a 'write' method!!! Crap API...
- {
- return 1; // we failed to request a read from that mcu - this really is just writing the mcu vaule on the bus
- }
- *dst = m_i2c.read(0);
- m_i2c.stop();
-
- return 0;
-
+ 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);
}
+
+void MMA8452::debugRegister(char reg) {
+ // get register value
+ char v = 0;
+ if(readRegister(reg,&v)) {
+ DBG("Error reading control register");
+ return;
+ }
+ // print out details
+ switch(reg) {
+ case MMA8452_CTRL_REG_1:
+ DBG("CTRL_REG_1 has value: 0x%x",v);
+ DBG(" 7 ALSP_RATE_1: %d",(v&0x80)>>7);
+ DBG(" 6 ALSP_RATE_0: %d",(v&0x40)>>6);
+ DBG(" 5 DR2: %d", (v&0x20)>>5);
+ DBG(" 4 DR1: %d", (v&0x10)>>4);
+ DBG(" 3 DR0: %d", (v&0x08)>>3);
+ DBG(" 2 LNOISE: %d", (v&0x04)>>2);
+ DBG(" 1 FREAD: %d", (v&0x02)>>1);
+ DBG(" 0 ACTIVE: %d", (v&0x01));
+ break;
+
+ case MMA8452_XYZ_DATA_CFG:
+ DBG("XYZ_DATA_CFG has value: 0x%x",v);
+ DBG(" 7 Unused: %d", (v&0x80)>>7);
+ DBG(" 6 0: %d", (v&0x40)>>6);
+ DBG(" 5 0: %d", (v&0x20)>>5);
+ DBG(" 4 HPF_Out: %d",(v&0x10)>>4);
+ DBG(" 3 0: %d", (v&0x08)>>3);
+ DBG(" 2 0: %d", (v&0x04)>>2);
+ DBG(" 1 FS1: %d", (v&0x02)>>1);
+ DBG(" 0 FS0: %d", (v&0x01));
+ switch(v&0x03) {
+ case 0:
+ DBG("Dynamic range: 2G");
+ break;
+ case 1:
+ DBG("Dynamic range: 4G");
+ break;
+ case 2:
+ DBG("Dynamic range: 8G");
+ break;
+ default:
+ DBG("Unknown dynamic range");
+ break;
+ }
+ break;
+
+ default:
+ DBG("Unknown register address: 0x%x",reg);
+ break;
+ }
+}
\ No newline at end of file