Diff: DMU.cpp

Revision:

0:e4342b551612

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/DMU.cpp	Mon Mar 11 16:34:51 2013 +0000
@@ -0,0 +1,169 @@
+#include "DMU.h"
+
+DMU::DMU(PinName MOSI, PinName MISO, PinName SCLK, 
+         PinName S0,   PinName S1,   PinName S2){
+    _spi = new SPI(MOSI, MISO, SCLK);               //communication
+    _cs = new BusOut(S0, S1, S2);                   //slave select/axis selct
+                                               
+    _init();
+    
+    
+} 
+
+float DMU::acceleration(char axis){
+
+    
+    bool correctRead;
+    do{
+        _selectAxis(axis);
+        correctRead = _write(0x01);
+    }while (!correctRead);
+    
+    short dispA = (data2<<8) | data3;
+    int negTester = 0x8000;
+    if (negTester & dispA) dispA = -1 * (65536 - dispA);
+    
+    return dispA * .00366;
+
+}
+
+float DMU::roll(){
+
+    bool correctRead;
+    do{
+        _selectAxis('x');
+        correctRead = _write(0x01);
+    }while (!correctRead);
+    
+    short dispA = (data0<<8) | data1;
+    int negTester = 0x8000;
+    if (negTester & dispA) dispA = -1 * (65536 - dispA);
+    
+    return dispA * .03125;
+
+}
+float DMU::pitch(){
+
+    bool correctRead;
+    do{
+        _selectAxis('y');
+        correctRead = _write(0x01);
+    }while (!correctRead);
+    
+    short dispA = (data0<<8) | data1;
+    int negTester = 0x8000;
+    if (negTester & dispA) dispA = -1 * (65536 - dispA);
+    
+    return dispA * .03125;
+
+}
+float DMU::yaw(){
+
+    bool correctRead;
+    do{
+        _selectAxis('z');
+        correctRead = _write(0x01);
+    }while (!correctRead);
+    
+    short dispA = (data0<<8) | data1;
+    int negTester = 0x8000;
+    if (negTester & dispA) dispA = -1 * (65536 - dispA);
+    
+    return dispA * .03125;
+
+}
+
+void DMU::test(){
+
+    bool correctRead;
+    do{
+        _selectAxis('z');
+        correctRead = _write(0x05);
+    }while (!correctRead);
+    
+    do{
+        _selectAxis('y');
+        correctRead = _write(0x05);
+    }while (!correctRead);
+    
+    do{
+        _selectAxis('x');
+        correctRead = _write(0x05);
+    }while (!correctRead);
+
+}
+
+ 
+ 
+/*  Init the DMU
+ *  
+ *  
+ */
+void DMU::_init() {
+    _repClock.start();              // start clock to allow first call of select axis to read from clock
+    _spi->frequency(1150000);       // f = 1.15MHz, max f = 1.25MHz, min f = 4kHz
+    _spi->format(8,0);              // 8 bits of data, CPOL = 0, CPHA = 0
+  
+}
+
+void DMU::_selectAxis(char axis) {
+    while (_repClock.read_ms() < 100);  //check to ensure device isn't read more than once every 100 ms
+    _repClock.stop();
+    _repClock.reset();
+    switch (axis){
+        case 'x':
+            _repClock.start();
+            _cs->write(6);              //drive SS to set x line low
+            break;
+        case 'y':
+            _repClock.start();
+            _cs->write(3);              //drive SS to set y line low
+            break;
+        case 'z':
+            _repClock.start();
+            _cs->write(5);              //drive SS to set z line low
+    }
+    wait(.000010);                      // wait time needed for device setup
+}
+ 
+void DMU::_deselectAxis() {
+
+    _cs->write(7);
+
+}
+
+bool DMU::_write(char controlByte) {
+
+    char status = _spi->write(controlByte);
+    wait(.0000015);
+    
+    data0 = _spi->write(0x00);
+    wait(.0000015);                             //min wait time between successive bytes is 1.1us
+    
+    data1 = _spi->write(0x00);
+    wait(.0000015);
+    
+    data2 = _spi->write(0x00);
+    wait(.0000015);
+    
+    data3 = _spi->write(0x00);
+    wait(.0000015);
+
+    char rCS = _spi->write(~controlByte);
+    _deselectAxis();                            //deselect chip to ensure message duration is under 270 us
+    
+    
+    return _correctChecksumReceived(status, rCS);
+
+
+
+}
+
+bool DMU::_correctChecksumReceived(char statusByte, char chkSum){
+
+    char calculatedChecksum = statusByte + data0 + data1 + data2 + data3;
+    
+    if ((char)~chkSum != calculatedChecksum) return 0;
+    return 1;
+
+}
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