Revision 0:fe041345c169, committed 2011-05-29

Comitter:

aberk

Date:

Sun May 29 14:13:20 2011 +0000

Child:

1:f5f2e79304fb

Commit message:

Version 1.0

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SCA3000.cpp	Sun May 29 14:13:20 2011 +0000
@@ -0,0 +1,165 @@
+/**
+ * @author Aaron Berk
+ *
+ * @section LICENSE
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @section DESCRIPTION
+ *
+ * SCA3000, triple axis, digital interface, accelerometer.
+ *
+ * Datasheet:
+ *
+ * http://www.sparkfun.com/datasheets/Sensors/Accelerometer/SCA3000-D01.pdf
+ */
+
+/**
+ * Includes
+ */
+#include "SCA3000.h"
+
+SCA3000::SCA3000(PinName mosi,
+                 PinName miso,
+                 PinName sck,
+                 PinName cs,
+                 PinName nr) : spi_(mosi, miso, sck), nCS_(cs), nR_(nr) {
+
+    //1MHz rate.
+    spi_.frequency(1000000);
+    //8-bit frame, POL = 0, PHA = 0.
+    spi_.format(8,0);
+    //Chip select is active low [so set it high initially].
+    nCS_ = 1;
+    //Pulse reset.
+    nR_ = 0;
+    wait(0.1);
+    nR_ = 1;
+
+    int status = 0;
+    //Check whether the device successfully reset by reading
+    //the CSME bit of the STATUS register.
+    //0 => no error
+    //1 => error
+    status = oneByteRead(SCA3000_STATUS_REG);
+    //CSME bit = 1... uh oh...
+    if (status & 0x2) {
+    
+    }
+
+}
+
+int SCA3000::getRevId(void) {
+
+    return oneByteRead(SCA3000_REVID_REG);
+
+}
+
+float SCA3000::getAcceleration(int axis) {
+
+    int acceleration = 0;
+    int axis_lsb     = 0;
+    int axis_msb     = 0;
+
+    switch (axis) {
+
+        case SCA3000_X_AXIS:
+
+            axis_lsb = oneByteRead(SCA3000_X_LSB);
+            axis_msb = oneByteRead(SCA3000_X_MSB);
+            
+            break;
+
+        case SCA3000_Y_AXIS:
+
+            axis_lsb = oneByteRead(SCA3000_Y_LSB);
+            axis_msb = oneByteRead(SCA3000_Y_MSB);
+            
+            break;
+
+        case SCA3000_Z_AXIS:
+
+            axis_lsb = oneByteRead(SCA3000_Z_LSB);
+            axis_msb = oneByteRead(SCA3000_Z_MSB);
+            
+            break;
+
+            //An invalid axis value has been passed.
+        default:
+        
+            break;
+
+    }
+
+    acceleration = ( axis_msb << 8 | axis_lsb );
+
+    return countsToMg(acceleration);
+
+}
+
+float SCA3000::countsToMg(int counts){
+
+    float acceleration = 0.0;
+
+    //If this looks like nonsense it's because
+    //the datasheet is completely wrong.
+    if(counts & 0x8000){
+        counts = (counts >> 3) & 0x1FFF;
+        counts = (~counts & 0x1FFF)+ 1;
+        acceleration = counts * -0.75;
+    }
+    else{
+        counts = (counts >> 3) & 0xFFF;
+        acceleration = counts * 0.75;
+    }
+    
+    return acceleration;
+
+}
+
+int SCA3000::oneByteRead(int address) {
+
+    //Register address sits in the first 6 bits of the transmission.
+    int tx = ((address << 2) | SCA3000_SPI_READ);
+    int rx = 0;
+
+    nCS_ = 0;
+    //Send address to read from.
+    spi_.write(tx);
+    //Read back contents of address.
+    rx = spi_.write(0x00);
+    nCS_ = 1;
+
+    return rx;
+
+}
+
+void SCA3000::oneByteWrite(int address, char data) {
+
+    //Register address sits in the first 6 bits of the transmission.
+    int tx = ((address << 2) | SCA3000_SPI_WRITE);
+
+    nCS_ = 0;
+    //Send address to write to.
+    spi_.write(tx);
+    //Send data to be written.
+    spi_.write(data);
+    nCS_ = 1;
+
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SCA3000.h	Sun May 29 14:13:20 2011 +0000
@@ -0,0 +1,131 @@
+/**
+ * @author Aaron Berk
+ *
+ * @section LICENSE
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @section DESCRIPTION
+ *
+ * SCA3000, triple axis, digital interface, accelerometer.
+ *
+ * Datasheet:
+ *
+ * http://www.sparkfun.com/datasheets/Sensors/Accelerometer/SCA3000-D01.pdf
+ */
+
+#ifndef MBED_SCA3000_H
+#define MBED_SCA3000_H
+
+/**
+ * Includes
+ */
+#include "mbed.h"
+
+/**
+ * Defines
+ */
+//Registers.
+#define SCA3000_REVID_REG  0x00
+#define SCA3000_STATUS_REG 0x02
+#define SCA3000_X_LSB      0x04
+#define SCA3000_X_MSB      0x05
+#define SCA3000_Y_LSB      0x06
+#define SCA3000_Y_MSB      0x07
+#define SCA3000_Z_LSB      0x08
+#define SCA3000_Z_MSB      0x09
+ 
+#define SCA3000_SPI_READ   0x00
+#define SCA3000_SPI_WRITE  0x02
+
+#define SCA3000_X_AXIS     0x00
+#define SCA3000_Y_AXIS     0x01
+#define SCA3000_Z_AXIS     0x02
+
+/**
+ * SCA3000, triple axis, digital interface, accelerometer.
+ */
+class SCA3000 {
+
+public:
+
+    /**
+     * Constructor.
+     *
+     * @param mosi mbed pin to use for MOSI line of SPI interface.
+     * @param miso mbed pin to use for MISO line of SPI interface.
+     * @param sck mbed pin to use for SCK line of SPI interface.
+     * @param cs mbed pin to use for not chip select line of SPI interface.
+     * @param nr mbed pin to use for the not reset line.
+     */
+    SCA3000(PinName mosi, PinName miso, PinName sck, PinName cs, PinName nr);
+    
+    /**
+     * Read the revision ID register on the device.
+     *
+     * @return The revision ID number.
+     */
+    int getRevId(void);
+    
+    /**
+     * Get the register contents acceleration value for the
+     * given axis.
+     *
+     * @param axis The axis to get acceleration values for.
+     *
+     * @return The acceleration on the specified axis in mg.
+     */
+    float getAcceleration(int axis);
+
+private:
+
+    SPI        spi_;
+    DigitalOut nCS_;
+    DigitalOut nR_;
+    
+    /**
+     * Converts the contents of acceleration registers (MSB << 8 | LSB)
+     * to mg.
+     * 
+     * @param counts The contents of acceleration registers.
+     *
+     * @return The acceleration in mg.
+     */
+    float countsToMg(int counts);
+    
+    /**
+     * Read one byte from a register on the device.
+     *
+     * @param address Address of the register to read.
+     *
+     * @return The contents of the register address.
+     */
+    int oneByteRead(int address);
+    
+    /**
+     * Write one byte to a register on the device.
+     *
+     * @param address Address of the register to write to.
+     * @param data The data to write into the register.
+     */
+    void oneByteWrite(int address, char data);
+
+};
+
+#endif /* MBED_SCA3000_H */