Diff: digipot.cpp

Revision:

0:57bdd27601ad

Child:

1:0b0025664bb7

diff -r 000000000000 -r 57bdd27601ad digipot.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/digipot.cpp	Fri Apr 03 20:04:16 2015 +0000
@@ -0,0 +1,71 @@
+//Digipot code with 2nd CAN Transceiver for testing
+
+#include "mbed.h"
+
+static int id = 0x04;       //Module CAN ID, to be assigned by keypad team.
+static double input_amp = 3.3; //input analog signal is 3.3V
+
+static double R1 = 10;    //Opamp resistor between output and inverting-input
+static double R2 = 5.6;    //Opamp resistor between inverting-input and ground
+static double gain = 1 + R2/R1; //Non-inverting opamp gain
+
+//Debugging Variables
+DigitalOut led1(LED1);  //debugging LED1
+Ticker ticker;  //triggers debugging send
+char counter = 0;   //Output amplitude
+CAN can2(p30, p29);                 //2nd debugging send transceiver
+
+//Values to be used in final implementation
+DigitalOut led2(LED2);  //debugging LED2
+DigitalOut CS(p8);                 // inverted chip select
+SPI spi(p5, p6, p7);               // mosi, miso, sclk
+CAN can1(p9, p10);                  //reading transceiver
+
+
+void digipot (int OutputAmp)
+{
+    CS=0;                       // Deselects the digipot
+    // Setup the spi for 8 bit data, high steady state clock,
+    // second edge capture, with a 1MHz clock rate
+    spi.format(8,3);
+    spi.frequency(1000000);
+
+    uint8_t wiper = uint8_t(OutputAmp*(255/(input_amp * gain)));    //Generates appropriate Wiper position
+    
+    spi.write(0x11);      // Write data command, potentiometer zero
+    spi.write(wiper);           // Writes wiper value
+    
+    CS=1;                       // Selects the digipot, and executes command
+}
+
+void send() //For debugging
+{
+    if(can2.write(CANMessage(id, &counter, 1))) {
+        counter++;
+        if(counter ==6)
+        {
+            counter = 0;    //reset counter
+        }
+    } 
+    led1 = !led1;
+}
+
+int main()
+{
+        ticker.attach(&send,10);    //Debugging: Changes output amplitude every 10 seconds
+        
+        int OutputAmp = 0;  //Default output amplitude value
+        digipot(OutputAmp);
+        
+        CANMessage msg;
+                
+        while(1)
+        {
+            if(can1.read(msg) && msg.id == id)
+            {
+                OutputAmp = msg.data[0];    //Input is an int 0,1,2,3,4,5
+                digipot(OutputAmp);     //set digipot value
+                led2 = !led2;
+            }
+        }
+}
\ No newline at end of file