Revision 3:2ce85aa45d7d, committed 2014-05-28

Comitter:

trm

Date:

Wed May 28 18:38:09 2014 +0000

Parent:

2:4c2f8a3549a9

Child:

4:e2fe752b881e

Commit message:

Updates to documentation and comments.

Changed in this revision

--- a/FXOS8700CQ.cpp	Wed May 28 17:08:33 2014 +0000
+++ b/FXOS8700CQ.cpp	Wed May 28 18:38:09 2014 +0000
@@ -8,18 +8,16 @@
 {
     // Initialization of the FXOS8700CQ
     dev_i2c.frequency(I2C_400K); // Use maximum I2C frequency
-    uint8_t data[6] = {0, 0, 0, 0, 0, 0}; // target device write address, single byte to write at address
+    uint8_t data[6] = {0, 0, 0, 0, 0, 0}; // to write over I2C: device register, up to 5 bytes data
 
     // TODO: verify WHOAMI?
 
-    // TODO: un-magic-number register configuration
-
     // Place peripheral in standby for configuration, resetting CTRL_REG1
     data[0] = FXOS8700CQ_CTRL_REG1;
     data[1] = 0x00; // this will unset CTRL_REG1:active
     write_regs(data, 2);
 
-    // Now that the device is in standby, configure registers
+    // Now that the device is in standby, configure registers at will
 
     // Setup for write-though for CTRL_REG series
     // Keep data[0] as FXOS8700CQ_CTRL_REG1
@@ -33,15 +31,15 @@
         FXOS8700CQ_CTRL_REG2_MODS2(1); // 0b01 gives low noise, low power oversampling mode
 
     // No configuration changes from default 0x00 in CTRL_REG3
-    // Interrupts will be active low
+    // Interrupts will be active low, their outputs in push-pull mode
     data[3] = 0x00;
 
     // FXOS8700CQ_CTRL_REG4;
     data[4] =
-        FXOS8700CQ_CTRL_REG4_INT_EN_DRDY;
+        FXOS8700CQ_CTRL_REG4_INT_EN_DRDY; // Enable the Data-Ready interrupt
 
     // No configuration changes from default 0x00 in CTRL_REG5
-    // Data ready interrupt will appear on INT2
+    // Data-Ready interrupt will appear on INT2
     data[5] = 0x00;
 
     // Write to the 5 CTRL_REG registers
@@ -153,6 +151,7 @@
     read_regs(FXOS8700CQ_XYZ_DATA_CFG, &data, 1);
     data &= FXOS8700CQ_XYZ_DATA_CFG_FS2(3); // mask with 0b11
 
+    // Choose output value based on masked data
     switch(data) {
         case FXOS8700CQ_XYZ_DATA_CFG_FS2(0):
             return 2;
@@ -167,6 +166,8 @@
 
 // Private methods
 
+// Excepting the call to dev_i2c.frequency() in the constructor,
+// the use of the mbed I2C class is restricted to these methods
 void FXOS8700CQ::read_regs(int reg_addr, uint8_t* data, int len)
 {
     char t[1] = {reg_addr};

--- a/FXOS8700CQ.h	Wed May 28 17:08:33 2014 +0000
+++ b/FXOS8700CQ.h	Wed May 28 18:38:09 2014 +0000
@@ -116,7 +116,7 @@
 * A driver on top of mbed-I2C to operate the FXOS8700CQ accelerometer/magnetometer
 * on the FRDM-K64F.
 *
-* Warning: incomplete code!
+* Code has been completed, but likely not optimized and potentially buggy.
 */
 class FXOS8700CQ
 {
@@ -137,9 +137,18 @@
 
     void enable(void);
     void disable(void);
+
+    /**
+    * @return the contents of device register FXOS8700CQ_WHOAMI 0x0D,
+    * should be FXOS8700CQ_WHOAMI_VAL 0xC7
+    */
     uint8_t get_whoami(void);
+    
+    /**
+    * @return the contents of device register FXOS8700CQ_STATUS 0x00
+    */
     uint8_t status(void);
-    
+
     /**
     * Data retrieval from the FXOS8700CQ
     *
@@ -148,10 +157,10 @@
     * @return 0 on success, non-zero on failure
     */
     uint8_t get_data(SRAWDATA *accel_data, SRAWDATA *magn_data);
-    
+
     /**
     * Retrieve the full-range scale value of the accelerometer
-    * 
+    *
     * @return 2, 4, or 8, depending on part configuration; 0 on error
     */
     uint8_t get_accel_scale(void);
@@ -161,7 +170,7 @@
 private:
     I2C dev_i2c; // instance of the mbed I2C class
     uint8_t dev_addr; // Device I2C address, in (7-bit << 1) form
-    bool enabled;
+    bool enabled; // keep track of enable bit of device
 
     // I2C helper methods
     void read_regs(int reg_addr, uint8_t* data, int len);