Diff: main.cpp

Revision:

67:f141b2ad5fcd

Parent:

66:0a43d8aeeb76

--- a/main.cpp	Tue Jun 26 17:52:09 2018 +0000
+++ b/main.cpp	Thu Aug 23 14:07:02 2018 +0000
@@ -1,14 +1,44 @@
 #include "mbed.h"
+// Bits are: Start (1), SGL/DIFF (1 for single), ODD/SIGN (0 for channel 0), MSBF (1 for MSB first)
+#define MCP3002_CH0 0x68  // 0110 1000
+#define MCP3002_CH1 0x78  // 0111 1000
 
-DigitalOut led1(LED1);
+Serial pc(USBTX, USBRX);
+SPI spi(p5, p6, p7); // mosi, miso, sclk
+DigitalOut cs(p20); // Chip select, active low
+AnalogOut aout(p18);
 
-// main() runs in its own thread in the OS
+// Note that using CS means that the chip itself has no address
+
 int main() {
-    while (true) {
-        led1 = !led1;
-        wait(0.02);
-        led1 = !led1;
-        wait(0.02);
+    pc.printf("Starting program \r\n");
+    // Chip must be deselected
+    cs = 1;
+    // Setup the spi for 8 bit data, CPOL = 0, CPHA = 0
+    // with a 10KHz clock rate
+    spi.format(8,0);
+    spi.frequency(10000);
+    int data1, data2, mask, channel;
+    // Supply voltage is nominally 3.3V
+    float VCC=3.3, vIn;
+    while(1) {
+        for (channel = 0; channel<2; channel++){
+            if(channel == 0){
+                mask = MCP3002_CH0;
+            }else{
+                mask = MCP3002_CH1;
+            }     
+            cs = 0;
+            data1 = spi.write(mask);
+            data2 = spi.write(0);
+            cs = 1;  
+// Format for MSB set
+            data1 &= 0x03;  // keep only three bits
+            data2 |= data1 << 8 ; // shift and add to LSB
+// data2 ranges from 0 to 1023 for voltage from 0 to VCC
+            vIn = VCC*data2/1000.;
+            pc.printf("Channel %i Voltage is %f \r\n",channel,vIn);
+        }
+        wait(1);
     }
 }
-