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#include "MMA7660.h"
MMA7660::MMA7660(PinName sda, PinName scl, bool active) : _i2c(sda, scl)
{
setActive(active);
samplerate = 64;
}
//Since the MMA lacks a WHO_AM_I register, we can only check if there is a device that answers to the I2C address
bool MMA7660::testConnection( void )
{
if (_i2c.write(MMA7660_ADDRESS, NULL, 0) == 0 )
return true;
else
return false;
}
void MMA7660::setActive(bool state)
{
char modereg = read(MMA7660_MODE_R);
modereg &= ~(1<<0);
//If it somehow was in testmode, disable that
if (modereg && (1<<2)) {
modereg &= ~(1<<2);
write(MMA7660_MODE_R, modereg);
}
modereg += state;
write(MMA7660_MODE_R, modereg);
}
void MMA7660::readData(int *data)
{
if (!active) {
setActive(true);
active = true;
wait(0.012 + 1/samplerate); //Wait until new sample is ready, my experience is that 1/samplerate isnt needed, but datasheet says so
}
char temp[3];
bool alert;
do {
alert = false;
read(MMA7660_XOUT_R, temp, 3);
for (int i = 0; i<3; i++) {
if (temp[i] > 63)
alert = true;
if (temp[i] > 31)
temp[i] += 128+64;
data[i] = (signed char)temp[i];
}
} while (alert);
if (!active)
setActive(false);
}
void MMA7660::readData(float *data)
{
int intdata[3];
readData(intdata);
for (int i = 0; i<3; i++)
data[i] = intdata[i]/MMA7660_SENSITIVITY;
}
float MMA7660::x( void )
{
return getSingle(0);
}
float MMA7660::y( void )
{
return getSingle(1);
}
float MMA7660::z( void )
{
return getSingle(2);
}
void MMA7660::setSampleRate(int samplerate)
{
setActive(false); //Not allowed to be active to change anything
int rates[] = {120, 64, 32, 16, 8, 4, 2, 1}; //Alowed samplerates (and their number in array is also number required for MMA)
int sampleLoc = 0, sampleError = 10000, temp;
for (int i = 0; i<8; i++) {
temp = abs( rates[i] - samplerate );
if (temp<sampleError) {
sampleLoc = i;
sampleError=temp;
}
}
//Update the samplerate reg
temp = read(MMA7660_SR_R);
temp &= ~0x07; //Awake sample rate are lowest 3 bit
temp |= sampleLoc;
write(MMA7660_SR_R, temp);
this->samplerate = rates[sampleLoc];
setActive(active); //Restore previous active state
}
MMA7660::Orientation MMA7660::getSide( void )
{
char tiltreg = read(MMA7660_TILT_R);
//We care about 2 LSBs
tiltreg &= 0x03;
if (tiltreg == 0x01)
return MMA7660::Front;
if (tiltreg == 0x02)
return MMA7660::Back;
return MMA7660::Unknown;
}
MMA7660::Orientation MMA7660::getOrientation( void )
{
char tiltreg = read(MMA7660_TILT_R);
//We care about bit 2, 3 and 4 (counting from zero)
tiltreg &= 0x07<<2;
tiltreg >>= 2;
if (tiltreg == 0x01)
return MMA7660::Left;
if (tiltreg == 0x02)
return MMA7660::Right;
if (tiltreg == 0x05)
return MMA7660::Down;
if (tiltreg == 0x06)
return MMA7660::Up;
return MMA7660::Unknown;
}
//////////////////////////////////////////////
///////////////PRIVATE////////////////////////
//////////////////////////////////////////////
void MMA7660::write(char address, char data)
{
char temp[2];
temp[0]=address;
temp[1]=data;
_i2c.write(MMA7660_ADDRESS, temp, 2);
}
char MMA7660::read(char address)
{
char retval;
_i2c.write(MMA7660_ADDRESS, &address, 1, true);
_i2c.read(MMA7660_ADDRESS, &retval, 1);
return retval;
}
void MMA7660::read(char address, char *data, int length)
{
_i2c.write(MMA7660_ADDRESS, &address, 1, true);
_i2c.read(MMA7660_ADDRESS, data, length);
}
float MMA7660::getSingle( int number )
{
if (!active) {
setActive(true);
wait(0.012 + 1/samplerate); //Wait until new sample is ready
}
signed char temp;
bool alert;
do {
alert = false;
temp = read(MMA7660_XOUT_R + number);
if (temp > 63)
alert = true;
if (temp > 31)
temp += 128+64;
} while (alert);
if (!active)
setActive(false);
return temp / MMA7660_SENSITIVITY;
}
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