Library for the MMA7660 triple axis accelerometer
Dependents: Websocket_Ethernet_acc app-board-Sprint-WS-Acc app-board-Ethernet-Websocket app-board-Wifly-Websocket ... more
Revision 0:7bc29a9ea016, committed 2012-10-14
- Comitter:
- Sissors
- Date:
- Sun Oct 14 08:02:53 2012 +0000
- Child:
- 1:8997a1b348dd
- Commit message:
- v0.1
Changed in this revision
MMA7660.cpp | Show annotated file Show diff for this revision Revisions of this file |
MMA7660.h | Show annotated file Show diff for this revision Revisions of this file |
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MMA7660.cpp Sun Oct 14 08:02:53 2012 +0000 @@ -0,0 +1,123 @@ +#include "MMA7660.h" + +MMA7660::MMA7660(PinName sda, PinName scl, PinName interrupt) : _i2c(sda, scl) +{ + _interrupt = interrupt; + active = false; + samplerate = 120; +} + +//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); +} + +//Add timeout! +void MMA7660::readData(int *data) +{ + if (!active) { + setActive(true); + active = true; + } + + 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); +} + +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::getX( void ) { + return getSingle(0); + } + +float MMA7660::getY( void ) { + return getSingle(1); + } + +float MMA7660::getZ( void ) { + return getSingle(2); + } + +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); + active = true; + } + + 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); + + return temp / MMA7660_SENSITIVITY; +} \ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MMA7660.h Sun Oct 14 08:02:53 2012 +0000 @@ -0,0 +1,115 @@ +#include "mbed.h" + + +#ifndef MMA7660_H +#define MMA7660_H + +#define MMA7660_ADDRESS 0x98 +#define MMA7660_SENSITIVITY 21.33 + +#define MMA7660_XOUT_R 0x00 +#define MMA7660_YOUT_R 0x01 +#define MMA7660_ZOUT_R 0x02 +#define MMA7660_MODE_R 0x07 + +class MMA7660 +{ +public: + /** + * Creates a new MMA7660 object + * + * @param sda - I2C data pin + * @param scl - I2C clock pin + * @param interrupt - Interrupt pin (default = NC) + */ + MMA7660(PinName sda, PinName scl, PinName interrupt = NC); + + /** + * Tests if communication is possible with the MMA7660 + * + * Because the MMA7660 lacks a WHO_AM_I register, this function can only check + * if there is an I2C device that responds to the MMA7660 address + * + * @param return - true for successfull connection, false for no connection + */ + bool testConnection( void ); + + /** + * Sets the active state of the MMA7660 + * + * Note: This is unrelated to awake/sleep mode + * + * @param state - true for active, false for standby + */ + void setActive( bool state); + + /** + * Reads acceleration data from the sensor + * + * When the parameter is a pointer to an integer array it will be the raw data. + * When it is a pointer to a float array it will be the acceleration in g's + * + * @param data - pointer to array with length 3 where the acceleration data will be stores, X-Y-Z + */ + void readData( int *data); + void readData( float *data); + + /** Get X-data + * + * @param return - X-acceleration in g's + */ + float getX( void ); + + /** Get Y-data + * + * @param return - Y-acceleration in g's + */ + float getY( void ); + + /** Get Z-data + * + * @param return - Z-acceleration in g's + */ + float getZ( void ); + + +private: + + /** + * Writes data to the device, could be private, but public is handy so you can transmit directly to the MPU. + * + * @param adress - register address to write to + * @param data - data to write + */ + void write( char address, char data); + + /** + * Read data from the device, could be private, but public is handy so you can transmit directly to the MPU. + * + * @param adress - register address to write to + * @return - data from the register specified by RA + */ + char read( char adress); + + /** + * Read multiple regigsters from the device, more efficient than using multiple normal reads. + * + * @param adress - register address to write to + * @param length - number of bytes to read + * @param data - pointer where the data needs to be written to + */ + void read( char adress, char *data, int length); + + /** + * Reads single axis + */ + float getSingle(int number); + + I2C _i2c; + bool active; + PinName _interrupt; + float samplerate; +}; + + +#endif