Diff: main.cpp

Revision:

0:646cd75bed54

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Oct 29 20:28:45 2010 +0000
@@ -0,0 +1,184 @@
+// 9430 Quadrature Decoder using mbed edge-triggered interrupts
+// 
+// Read quadrature encoder and drive LEDs
+// Version 0.1
+// Created by Wayne Chin
+// October 28, 2010
+
+#include "mbed.h"
+
+#define ON 0 // LED drives are inverted
+#define OFF 1 // LED drives are inverted
+#define MAXAMPS200 200
+#define MINAMPSET 25
+#define DEBOUNCETIME 6000 // Debounce delay in us
+
+// mbed LEDs
+DigitalOut led1(LED1);
+DigitalOut led2(LED2);
+DigitalOut led3(LED3);
+DigitalOut led4(LED4);
+
+// Quadrature encoder inputs
+InterruptIn quada(p21);
+InterruptIn quadb(p22);
+InterruptIn quadsw(p30);
+
+// mbed API timers used for edge sensing and debouncing
+Timer debouncetimerrisea;
+Timer debouncetimerfalla;
+Timer debouncetimerriseb;
+Timer debouncetimerfallb;
+Timeout debouncerisea;
+Timeout debouncefalla;
+Timeout debounceriseb;
+Timeout debouncefallb;
+
+Ticker updateserial;
+Serial pc(USBTX, USBRX); // tx, rx
+
+int counter; // Global counter variable
+
+void serialout()
+{
+    pc.printf("%d\n\r", counter);
+}
+
+void display()
+{
+    if (counter > MAXAMPS200)
+        counter = MAXAMPS200; // Clip counter at high end
+    else if (counter < MINAMPSET)
+        counter = MINAMPSET; // Clip at low end
+    switch (counter % 4) // Get 2 LSBs and display sequence on mbed LEDs
+    {
+        case 0:
+            led1 = 1; led2 = 0; led3 = 0; led4 = 0;
+            break;
+        case 1:
+            led1 = 0; led2 = 1; led3 = 0; led4 = 0;
+            break;
+        case 2:
+            led1 = 0; led2 = 0; led3 = 1; led4 = 0;
+            break;
+        default:
+            led1 = 0; led2 = 0; led3 = 0; led4 = 1;
+            break;
+    } // switch
+}
+
+// Read quadrature encoder, update counter variable, and update LEDs
+// Quadrature clockwise states: 00 -> 10 -> 11 -> 01
+// Quadrature counter-clockwise states: 00 -> 01 -> 11 -> 10
+void checkrisea()
+{
+    debouncetimerrisea.stop();
+    debouncetimerrisea.reset();
+    debouncerisea.detach();
+    if (quada == 1 && quadb == 0)
+        counter++;
+    else if (quada == 1 && quadb == 1)
+        counter--;
+    display();
+}
+
+void checkfalla()
+{
+    debouncetimerfalla.stop();
+    debouncetimerfalla.reset();
+    debouncefalla.detach();
+    if (quada == 0 && quadb == 1)
+        counter++;
+    else if (quada == 0 && quadb == 0)
+        counter--;
+    display();
+}
+
+void checkriseb()
+{
+    debouncetimerriseb.stop();
+    debouncetimerriseb.reset();
+    if (quadb == 1 && quada == 1)
+        counter++;
+    else if (quadb == 1 && quada == 0)
+        counter--;
+    display();
+}
+
+void checkfallb()
+{
+    debouncetimerfallb.stop();
+    debouncetimerfallb.reset();
+    if (quadb == 0 && quada == 0)
+        counter++;
+    else if (quadb == 0 && quada == 1)
+        counter--;
+    display();
+}
+
+// Start of edge-triggered interrupts
+void risea()
+{
+    if (debouncetimerrisea.read_ms() == 0)
+    {
+        debouncetimerrisea.start();
+        debouncerisea.attach_us(&checkrisea, DEBOUNCETIME); // Check on switch later
+    }
+} // risea()
+
+void falla()
+{
+    if (debouncetimerfalla.read_ms() == 0)
+    {
+        debouncetimerfalla.start();
+        debouncefalla.attach_us(&checkfalla, DEBOUNCETIME); // Check on switch later
+    }
+} // falla()
+
+void riseb()
+{
+    if (debouncetimerriseb.read_ms() == 0)
+    {
+        debouncetimerriseb.start();
+        debounceriseb.attach_us(&checkriseb, DEBOUNCETIME); // Check on switch later
+    }
+} // riseb()
+
+void fallb()
+{
+    if (debouncetimerfallb.read_ms() == 0)
+    {
+        debouncetimerfallb.start();
+        debouncefallb.attach_us(&checkfallb, DEBOUNCETIME); // Check on switch later
+    }
+} // fallb()
+
+int main() {
+    quada.mode(PullUp); // Enable pullup
+    quadb.mode(PullUp); // Enable pullup
+    quadsw.mode(PullUp); // Enable pullup
+    quada.rise(&risea); // Call function risea() on rising edge
+    quada.fall(&falla); // Call function falla() on falling edge
+    quadb.rise(&riseb); // Call function riseb() on rising edge
+    quadb.fall(&fallb); // Call function fallb() on falling edge
+    counter = 0; // Reset counter
+
+    pc.baud(19200);
+    pc.printf("\n\rConnected to mBed...\r\n");
+    
+    debouncetimerrisea.stop();
+    debouncetimerrisea.reset();
+    debouncetimerfalla.stop();
+    debouncetimerfalla.reset();
+    debouncetimerriseb.stop();
+    debouncetimerriseb.reset();
+    debouncetimerfallb.stop();
+    debouncetimerfallb.reset();
+
+    // Set up interrupt call for serial port update
+    //updateserial.attach_us(&serialout, 500000); // setup updateserial to call serialout every 500 ms
+
+    while (1)
+    {
+    }// while (1)
+} // main()