S5_mbed
library mma8452
Fork of
MMA8452
by 
Ashley Mills
Diff: MMA8452.cpp
- Revision:
- 8:89272163f395
- Parent:
- 7:8aa5123d403f
- Parent:
- 6:f6bde04bf8be
- Child:
- 9:dfb0f6a7a455
diff -r 8aa5123d403f -r 89272163f395 MMA8452.cpp
--- a/MMA8452.cpp Thu Oct 17 09:40:10 2013 +0000
+++ b/MMA8452.cpp Thu Oct 17 10:08:51 2013 +0000
@@ -19,20 +19,19 @@
# include "MMA8452.h"
-
-
-
-
-
// Connect module at I2C address using I2C port pins sda and scl
Accelerometer_MMA8452::Accelerometer_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;
}
// Destroys instance
-Accelerometer_MMA8452::~Accelerometer_MMA8452()
+Accelerometer_MMA8452::~Accelerometer_MMA8452()
{
}
@@ -40,75 +39,46 @@
// Setting the control register bit 1 to true to activate the MMA8452
int Accelerometer_MMA8452::activate()
{
- char mcu_address = (MMA8452_ADDRESS<<1);
- char init[2];
- init[0] = CTRL_REG_1; // control register 1
- init[1] = ACTIVE; // set to active
+ // set control register 1 to active
+ char init[2] = {CTRL_REG_1,ACTIVE};
- if(m_i2c.write(mcu_address,init,2) == 0)
- {
- return 0; // return 0 to indicate success
- }
- else
- {
- return 1; // crumbs it failed!!!
- }
-
+ // perform write and return error code
+ return m_i2c.write(_writeAddress,init,2);
}
// 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 Accelerometer_MMA8452::get_CTRL_Reg1(int& CTRL_Reg)
-{
+int Accelerometer_MMA8452::get_CTRL_Reg1(int* CTRL_Reg)
{
- 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
+ if( m_i2c.write(_writeAddress) == 0)
{
- return 1; // we failed to write the mcu address on the bus to initiate dialogue
+ return 1; // we failed to write the mcu address on the bus to initiate dialogue
}
if( m_i2c.write( CTRL_REG_1) == 0)
{
return 1; // we failed to write 'status' 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...
+ 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
}
- CTRL_Reg = m_i2c.read(0);
+ *CTRL_Reg = m_i2c.read(0);
m_i2c.stop();
return 0;
-
-
-}
-
-
-
-
}
// Setting the control register bit 1 to true to activate the MMA8452
int Accelerometer_MMA8452::standby()
{
- char mcu_address = (MMA8452_ADDRESS<<1);
- char init[2];
- init[0] = CTRL_REG_1; // control register 1
- init[1] = STANDBY; // set to standby
+ // set control register 1 to standby
+ char init[2] = {CTRL_REG_1,STANDBY};
- if(m_i2c.write(mcu_address,init,2) == 0)
- {
- // pc.printf("The initialisation worked");
- return 0; // return 0 to indicate success
- }
- else
- {
- // pc.printf("The initialisation failed");
- return 1; // crumbs it failed!!!
- }
-
+ // write to the register and return the error code
+ return m_i2c.write(_writeAddress,init,2);
}
@@ -126,9 +96,8 @@
// Get real time status of device - it can be STANDBY, WAKE or SLEEP
int Accelerometer_MMA8452::get_SystemMode(int& deviceSystemMode)
{
- 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
+ if( m_i2c.write(_writeAddress) == 0)
{
return 1; // we failed to write the mcu address on the bus to initiate dialogue
}
@@ -137,7 +106,7 @@
return 1; // we failed to write 'status' 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...
+ 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
}
@@ -153,18 +122,17 @@
// Get real time status of device - it can be STANDBY, WAKE or SLEEP
int Accelerometer_MMA8452::get_Status(int& deviceStatus)
{
- 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
+ if( m_i2c.write(_writeAddress) == 0) // tell the bus this is a write
{
return 1; // we failed to write the mcu address on the bus to initiate dialogue
}
- if( m_i2c.write( STATUS) == 0)
+ if( m_i2c.write(STATUS) == 0)
{
return 1; // we failed to write 'status' 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...
+ 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
}
@@ -179,9 +147,8 @@
// Get device ID
int Accelerometer_MMA8452::get_DeviceID(int& deviceID)
{
- 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
+ if( m_i2c.write(_writeAddress) == 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
}
@@ -190,7 +157,7 @@
return 1; // we failed to write 'who am i' 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...
+ 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
}
@@ -226,6 +193,25 @@
}
*/
+int Accelerometer_MMA8452::read_raw(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(m_i2c.read(_readAddress,dst,len)==0)
+ {
+ return 0;
+ }
+ }
+
+ // failure case, zero array and return error
+ for(int i=0; i<len; i++) {
+ dst[i] = 0x00;
+ }
+ return 1;
+}
// Reads x data. This method reads two registers containing the x-axis values from the accelerometer.
// It takes a 2 byte char array and copies the register values into the buffer. If it fails the char array
@@ -233,37 +219,23 @@
// the raw data.
//int Accelerometer_MMA8452::read_x(int& xaxisLSB)
int Accelerometer_MMA8452::read_x_raw(char *xaxis)
-{
- char mcu_address = (MMA8452_ADDRESS<<1); // this is the slave address on the bus we want data from
- char xaxis_buffer[2]; // this will contain data from that register
- char xaxis_register[1];
- xaxis_register[0] = OUT_X_MSB; // this is the register we want to get data from
+{
+ // this is the register we want to get data from
+ char xaxis_register[1] = {OUT_X_MSB};
//signed short s = 0;
- if(m_i2c.write(mcu_address,xaxis_register,1,true) == 0)
+ if(m_i2c.write(_writeAddress,xaxis_register,1,true) == 0)
{
- if(m_i2c.read(mcu_address,xaxis_buffer,2) == 0)
+ if(m_i2c.read(_readAddress,xaxis,2)==0)
{
- //strcpy(xaxis, xaxis_buffer);
- memcpy(xaxis, xaxis_buffer, 2);
- //xaxis[0] = 0x00; // make sure the array is set to zero
- //xaxis[1] = 0x00;
- //s = *reinterpret_cast<short*>(&xaxis);
- return 0; // great we got the two octets
- }
- else
- {
- xaxis[0] = 0x00; // make sure the array is set to zero
- xaxis[1] = 0x00;
- return 1; // failed to read the 12 bit x value
+ return 0;
}
}
- else
- {
- xaxis[0] = 0x00; // make sure the array is set to zero
- xaxis[1] = 0x00;
- return 1; // failed to write and request the OUT_X_MSB bit
- }
+
+ // failure case
+ xaxis[0] = 0x00; // make sure the array is set to zero
+ xaxis[1] = 0x00;
+ return 1; // failed to write and request the OUT_X_MSB bit
}
@@ -272,38 +244,8 @@
// is set to '0'. It returns '0' success '1' fail. This method does nothing to the registers - just returns
// the raw data.
-int Accelerometer_MMA8452::read_y_raw(char *yaxis)
-{
- char mcu_address = (MMA8452_ADDRESS<<1); // this is the slave address on the bus we want data from
- char yaxis_buffer[2]; // this will contain data from that register
- char yaxis_register[1];
- yaxis_register[0] = OUT_Y_MSB; // this is the register we want to get data from
- //signed short s = 0;
-
- if(m_i2c.write(mcu_address,yaxis_register,1,true) == 0)
- {
- if(m_i2c.read(mcu_address,yaxis_buffer,2) == 0)
- {
- //strcpy(yaxis, yaxis_buffer);
- memcpy(yaxis, yaxis_buffer, 2);
- //yaxis[0] = 0x00; // make sure the array is set to zero
- //yaxis[1] = 0x00;
- //s = *reinterpret_cast<short*>(&xaxis);
- return 0; // great we got the two octets
- }
- else
- {
- yaxis[0] = 0x00; // make sure the array is set to zero
- yaxis[1] = 0x00;
- return 1; // failed to read the 12 bit y value
- }
- }
- else
- {
- yaxis[0] = 0x00; // make sure the array is set to zero
- yaxis[1] = 0x00;
- return 1; // failed to write and request the OUT_Y_MSB bit
- }
+int Accelerometer_MMA8452::read_y_raw(char *yaxis) {
+ return read_raw(OUT_Y_MSB,yaxis,2);
}
@@ -315,37 +257,7 @@
int Accelerometer_MMA8452::read_z_raw(char *zaxis)
{
- char mcu_address = (MMA8452_ADDRESS<<1); // this is the slave address on the bus we want data from
- char zaxis_buffer[2]; // this will contain data from that register
- char zaxis_register[1];
- zaxis_register[0] = OUT_Z_MSB; // this is the register we want to get data from
- //signed short s = 0;
-
- if(m_i2c.write(mcu_address,zaxis_register,1,true) == 0)
- {
- //if(m_i2c.read(mcu_address,zaxis_buffer,2) == 0)
- if(m_i2c.read(mcu_address,zaxis,2) == 0)
- {
- //strcpy(yaxis, yaxis_buffer);
- //memcpy(zaxis, zaxis_buffer, 2);
- //yaxis[0] = 0x00; // make sure the array is set to zero
- //yaxis[1] = 0x00;
- //s = *reinterpret_cast<short*>(&xaxis);
- return 0; // great we got the two octets
- }
- else
- {
- zaxis[0] = 0x00; // make sure the array is set to zero
- zaxis[1] = 0x00;
- return 1; // failed to read the 12 bit y value
- }
- }
- else
- {
- zaxis[0] = 0x00; // make sure the array is set to zero
- zaxis[1] = 0x00;
- return 1; // failed to write and request the OUT_Y_MSB bit
- }
+ return read_raw(OUT_Z_MSB,zaxis,2);
}
@@ -444,13 +356,22 @@
char Accelerometer_MMA8452::read_reg(char addr)
{
- m_i2c.start(); // Start
- m_i2c.write(0x98); // A write to device 0x98
- m_i2c.write(addr); // Register to read
- m_i2c.start();
- m_i2c.write(0x99); // Read from device 0x99
- char c = m_i2c.read(0); // Read the data
- m_i2c.stop();
+ m_i2c.start();
+ if( m_i2c.write(_writeAddress) == 0)
+ {
+ return 1; // we failed to write the mcu address on the bus to initiate dialogue
+ }
+ 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
+ }
+ char c = m_i2c.read(0);
+ m_i2c.stop();
return c;