Diff: main.cpp

Revision:

0:6ecb1db6315e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Dec 13 21:22:07 2010 +0000
@@ -0,0 +1,141 @@
+#include "mbed.h"
+#include "extra.h"
+
+#define MARK 125  // 2000Hz 
+#define SPACE 250    //1000Hz
+#define BAUD 300
+#define BIT_PERIOD_US 1/BAUD
+
+//DigitalOut led(LED1);
+PwmOut led(p21);
+int output=0;
+int buf_mod[10]={0};
+int buf_index = 0;
+Timeout stop;
+Serial bt(p9, p10); // tx, rx
+
+
+void stop_pwm(void);
+void read_serial(void);
+int main() {
+
+    int i;
+    pc.baud(115200);
+    bt.baud(115200); 
+    pc.attach(&read_serial);
+    bt.attach(&read_serial); 
+    timerSetup();
+    int bit_index = 0;
+    float period;
+    state = IDLE;
+
+    while (1) {
+
+
+        if (output==0 && buf_mod[0] != 0) {
+            if (!bit_index) {
+
+                led=0.5;
+                led.period_us(SPACE);
+                //pc.printf("start bit\n");
+                stop.attach_us(&stop_pwm,1000000*(float)BIT_PERIOD_US);
+                bit_index++;
+                output=1;
+                continue;
+            }
+            period = ( 0x01 & (buf_mod[0] >> (bit_index-1)))? MARK:SPACE ;
+            led = 0.5;
+            pc.printf("Bit=%c", (period == MARK)?'H':'L' );
+
+            led.period_us(period);
+            stop.attach_us(&stop_pwm,1000000*(float)BIT_PERIOD_US);
+
+            bit_index++;
+            output = 1;
+
+            //Transmission complete
+            if (bit_index == 9) {
+
+                bit_index = 0;
+                buf_index--;
+                i=0;
+                led.period_us(MARK);
+                //while (buf[i] != 0) {
+                while (i <= buf_index) {
+                    buf_mod[i] = buf_mod[i+1];
+                    i++;
+                }
+                buf_mod[buf_index]=0;
+
+            }
+        }
+
+
+        // DEMOD:
+        if ( state == IDLE && n_long_periods == 3 ) {
+            pc.printf("START ");
+            state = READING;
+            buf = 0;
+            bit_count=0;
+            n_long_periods = 0;
+        } else if (state == READING ) {
+            if (n_short_periods > 150 ) {
+                // Error condition : You ve missed a bit
+                state = IDLE;
+                pc.printf("\n Error buf = %d",buf);
+                buf = 0;
+                bit_count = 0;
+                continue;
+            }
+
+            if (n_short_periods == 90) {
+                pc.printf("MARK ");
+                buf = (0x80 | (buf >>1));
+                bit_count++;
+
+
+            }
+            if (n_short_periods >100 ) {
+                n_short_periods = 0;
+            }
+
+            if (n_long_periods == 4 ) {
+
+                pc.printf("SPACE ");
+                buf = buf >>1;
+                bit_count++;
+                n_long_periods=0;
+            }
+
+            if (bit_count == 8 ) {
+                // all bits received
+                pc.printf("\n Rx from UE = %c",buf);
+                bt.putc(buf); 
+                state = IDLE;
+                buf = 0;
+                bit_count=0 ;
+            }
+        }
+    }
+}
+void read_serial(void) {
+
+    if (pc.readable()) {
+
+        buf_mod[buf_index++] = (int)pc.getc();
+        //pc.printf("%d",buf[buf_index-1]);
+        //buf[buf_index++]=171;
+        buf_mod[buf_index]= 0;
+    }
+    if (bt.readable()) {
+
+        buf_mod[buf_index++] = (int)bt.getc();
+        //pc.printf("%d",buf[buf_index-1]);
+        //buf[buf_index++]=171;
+        buf_mod[buf_index]= 0;
+    }
+}
+void stop_pwm(void) {
+    output = 0;
+    //led = 0;
+}
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