Vali Abdrakhmanov
1
Diff: MMA8452.h
- Revision:
- 21:a92a632a0cc7
- Parent:
- 20:d55e9d7eb17e
- Child:
- 22:32dff3c99c30
--- a/MMA8452.h Fri Mar 07 11:55:30 2014 +0000
+++ b/MMA8452.h Fri Mar 07 14:53:40 2014 +0000
@@ -107,7 +107,10 @@
#define MMA8452_STATUS_ZDR_MASK 0x04
#define MMA8452_STATUS_YDR_MASK 0x02
#define MMA8452_STATUS_XDR_MASK 0x01
-
+
+/**
+ * Wrapper for the MMA8452 I2C driven accelerometer.
+ */
class MMA8452 {
public:
@@ -136,8 +139,7 @@
RATE_1_563,
RATE_UNKNOWN
};
-
-
+
/**
* Create an accelerometer object connected to the specified I2C pins.
*
@@ -162,84 +164,120 @@
* @return 0 on success, 1 on failure.
*/
int standby();
-
- /** Initialization of device MMA8452 (required)
- */
- void init();
/**
* Read the device ID from the accelerometer (should be 0x2a)
*
- * @param pointer to store the ID
+ * @param dst pointer to store the ID
* @return 0 on success, 1 on failure.
*/
int getDeviceID(char* dst);
+ /**
+ * Read the MMA8452 status register.
+ *
+ * @param dst pointer to store the register value.
+ * @ return 0 on success, 1 on failure.
+ */
int getStatus(char* dst);
/**
- * Read the x,y, and z registers of the MMA8452.
+ * Read the raw x, y, an z registers of the MMA8452 in one operation.
+ * All three registers are read sequentially and stored in the provided buffer.
+ * The stored values are signed 2's complement left-aligned 12 or 8 bit integers.
*
* @param dst The destination buffer. Note that this needs to be 3 bytes for
* BIT_DEPTH_8 and 6 bytes for BIT_DEPTH_12. It is upto the caller to ensure this.
* @return 0 for success, and 1 for failure
+ * @sa setBitDepth
*/
int readXYZRaw(char *dst);
+ /// Read the raw x register into the provided buffer. @sa readXYZRaw
int readXRaw(char *dst);
+ /// Read the raw y register into the provided buffer. @sa readXYZRaw
int readYRaw(char *dst);
+ /// Read the raw z register into the provided buffer. @sa readXYZRaw
int readZRaw(char *dst);
/**
- * Read the x, y, and z counts of the MMA7452 axes.
+ * Read the x, y, and z signed counts of the MMA8452 axes.
*
* Count resolution is either 8 bits or 12 bits, and the range is either +-2G, +-4G, or +-8G
- * depending on settings.
+ * depending on settings. The number of counts per G are 1024, 512, 256 for 2,4, and 8 G
+ * respectively at 12 bit resolution and 64, 32, 16 for 2, 4, and 8 G respectively at
+ * 8 bit resolution.
*
* This function queries the MMA8452 and returns the signed counts for each axes.
*
* @param x Pointer to integer to store x count
* @param y Pointer to integer to store y count
* @param z Pointer to integer to store z count
- * @return 0 on success, 1 on failure
+ * @return 0 on success, 1 on failure.
*/
int readXYZCounts(int *x, int *y, int *z);
+
+ /// Read the x axes signed count. @sa readXYZCounts
int readXCount(int *x);
+ /// Read the y axes signed count. @sa readXYZCounts
int readYCount(int *y);
+ /// Read the z axes signed count. @sa readXYZCounts
int readZCount(int *z);
+ /**
+ * Read the x, y, and z accelerations measured in G.
+ *
+ * The measurement resolution is controlled via setBitDepth which can
+ * be 8 or 12, and by setDynamicRange, which can be +-2G, +-4G, or +-8G.
+ *
+ * @param x A pointer to the double to store the x acceleration in.
+ * @param y A pointer to the double to store the y acceleration in.
+ * @param z A pointer to the double to store the z acceleration in.
+ *
+ * @return 0 on success, 1 on failure.
+ */
int readXYZGravity(double *x, double *y, double *z);
- int readXGravity(double *x);
- int readYGravity(double *y);
- int readZGravity(double *z);
- /// Returns 1 if data has been internally sampled (is available) for the x-axis since last read, 0 otherwise.
- int isXReady();
-
- /// Returns 1 if data has been internally sampled (is available) for the y-axis since last read, 0 otherwise.
- int isYReady();
-
- /// Returns 1 if data has been internally sampled (is available) for the z-axis since last read, 0 otherwise.
- int isZReady();
+ /// Read the x gravity in G into the provided double pointer. @sa readXYZGravity
+ int readXGravity(double *x);
+ /// Read the y gravity in G into the provided double pointer. @sa readXYZGravity
+ int readYGravity(double *y);
+ /// Read the z gravity in G into the provided double pointer. @sa readXYZGravity
+ int readZGravity(double *z);
/// Returns 1 if data has been internally sampled (is available) for all axes since last read, 0 otherwise.
int isXYZReady();
+ /// Returns 1 if data has been internally sampled (is available) for the x-axis since last read, 0 otherwise.
+ int isXReady();
+ /// Returns 1 if data has been internally sampled (is available) for the y-axis since last read, 0 otherwise.
+ int isYReady();
+ /// Returns 1 if data has been internally sampled (is available) for the z-axis since last read, 0 otherwise.
+ int isZReady();
/**
- * Read from specified MMA8452 register.
+ * Reads a single byte from the specified MMA8452 register.
*
- * @param addr The internal registeraddress of the MMA8452
- * @return The value of the register
+ * @param addr The internal register address.
+ * @param dst The destination buffer address.
+ * @return 1 on success, 0 on failure.
*/
int readRegister(char addr, char *dst);
+ /**
+ * Reads n bytes from the specified MMA8452 register.
+ *
+ * @param addr The internal register address.
+ * @param dst The destination buffer address.
+ * @param nbytes The number of bytes to read.
+ * @return 1 on success, 0 on failure.
+ */
int readRegister(char addr, char *dst, int nbytes);
/**
* Write to the specified MMA8452 register.
*
* @param addr The internal register address
- * @param data Data to write
+ * @param data Data byte to write
*/
int writeRegister(char addr, char data);
@@ -247,15 +285,11 @@
* Write a data buffer to the specified MMA8452 register.
*
* @param addr The internal register address
- * @param data Data buffer to write
+ * @param data Pointer to data buffer to write
* @param nbytes The length of the data buffer to write
*/
int writeRegister(char addr, char *data, int nbytes);
- int logicalANDRegister(char addr, char mask);
- int logicalORRegister(char addr, char mask);
- int logicalXORRegister(char addr, char mask);
-
int setDynamicRange(DynamicRange range, int toggleActivation=1);
int setBitDepth(BitDepth depth, int toggleActivation=1);
int setDataRate(DataRateHz dataRate, int toggleActivation=1);
@@ -269,13 +303,34 @@
#endif
private:
- int readRaw(char src, char *dst, int len);
+ /**
+ * Reads the specified register, applies the mask with logical AND, logical ORs the value
+ * and writes back the result to the register. If toggleActivation is set to true then the
+ * device is put in standby before the operation, and activated at the end.
+ * Setting it to false is useful for setting options on a device that you want to keep in
+ * standby.
+ */
int maskAndApplyRegister(char reg, char mask, char value, int toggleActivation);
+ /// Reads the specified register, applies the mask with logical AND, and writes the result back.
+ int logicalANDRegister(char addr, char mask);
+ /// Reads the specified register, applies the mask with logical OR, and writes the result back.
+ int logicalORRegister(char addr, char mask);
+ /// Reads the specified register, applies the mask with logical XOR, and writes the result back.
+ int logicalXORRegister(char addr, char mask);
+
+ /// Converts the 12-bit two's complement number in buf to a signed integer. Returns the integer.
int twelveBitToSigned(char *buf);
+ /// Converts the 8-bit two's complement number in buf to a signed integer. Returns the integer.
int eightBitToSigned(char *buf);
+
+ /// Converts a count to a gravity using the supplied countsPerG. Returns the gravity.
double convertCountToGravity(int count, int countsPerG);
- char getMaskedRegister(int reg, char mask);
+
+ /// Reads the register at addr, applies the mask with logical AND, and returns the result.
+ char getMaskedRegister(int addr, char mask);
+
+ /// Get the counts per G for the current settings of bit depth and dynamic range.
int getCountsPerG();
I2C _i2c;
@@ -284,6 +339,5 @@
int _writeAddress;
BitDepth _bitDepth;
- DynamicRange _dynamicRange;
-
+ DynamicRange _dynamicRange;
};
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