main.cpp

00001 #include "mbed.h"
00002 #include "FastIO.h"
00003 #include "FastPWM.h"
00004 
00005 FastOut<LED1> led;
00006 
00007 //Pin 29 and 30 are connected to pin 21
00008 FastIn<p29> CAP_2_1_input;
00009 FastIn<p30> CAP_2_0_input;
00010 FastPWM pwm(p21);
00011 
00012 
00013 Serial pc(USBTX, USBRX); // tx, rx
00014 
00015 #define TIM2CR0 LPC_TIM2->CR0
00016 #define TIM2CR1 LPC_TIM2->CR1
00017 
00018 //void _cap_2_1_falling() {
00019   //  pc.printf("Interrupt: %X\n", LPC_TIM2->IR);
00020     //led = 1;
00021 //}
00022 
00023 int main()
00024 {
00025     
00026     unsigned int ticks = 226;
00027     
00028     // This signal should give a manchester encoded 101010101
00029     pwm.period_ticks(ticks);
00030     pwm.pulsewidth_ticks(ticks / 2);
00031     
00032     // Setup TIM2
00033     
00034     // SC
00035     LPC_SC->PCONP |= (1<<22);               // Power on the Timer2
00036     LPC_SC->PCLKSEL1 &= ~(3<<12);           // Select CCLK/4 for TIM2 (whipes previous clock setting)
00037     LPC_SC->PCLKSEL1 |= (1<<12);            // Select CCLK for TIM2
00038     
00039     // CCR
00040     LPC_TIM2->CCR |= (3 << 1);  // Set CAP2.0 on falling edge with interrupt
00041     LPC_TIM2->CCR |= (1 << 3);  // Set CAP2.1 on rising edge
00042        
00043     pc.printf("CCR: %X\n", LPC_TIM2->CCR);
00044 
00045     // TCR
00046     LPC_TIM2->TCR = 0x0002;                  // Reset TIM2
00047     LPC_TIM2->TCR = 0x0001;                  // Enable TIM2
00048     
00049     bool buffer [16];
00050     int bits = 0;
00051         
00052     //NVIC_DisableIRQ(TIMER2_IRQn);
00053     //NVIC_SetVector(TIMER2_IRQn, (uint32_t)&_cap_2_1_falling);
00054     //NVIC_EnableIRQ(TIMER2_IRQn);
00055     
00056     while(1) {        
00057         
00058         //pc.printf("Interrupt: %X\n", LPC_TIM2->IR);
00059 
00060         // Poll CRO (falling edge) intterupt
00061         if (LPC_TIM2->IR & (1 << 4)) {
00062             
00063             led = 1;
00064             
00065             wait(100);
00066             
00067             led = 0;
00068             
00069             int diff = (TIM2CR0 - TIM2CR1) % 0xFFFFFFFF;
00070             
00071             if (diff > 90 && diff < 136) {          // Check if diff is equal to T=1/848kHz with 20% error
00072                 // bit transition                
00073 
00074                 if (bits == 0) {                     // Start of sequence
00075                     buffer[0] = 1;
00076                 } else {
00077                     buffer[bits] = !buffer[bits-1];
00078                 }
00079                 
00080                 pc.printf("Trasition: %u\n", diff);
00081                 
00082             } else if (diff > 45 && diff < 68) {    // Check if diff is equal to T/2
00083                 // repeat last bit
00084                 
00085                 if (bits == 0) {                     // Start of sequence
00086                     buffer[0] = 1;
00087                 } else {
00088                     buffer[bits] = buffer[bits-1];
00089                 }
00090                 
00091                 pc.printf("Repeat: %u\n", diff);
00092 
00093             } else {
00094                 // error, default to 1 
00095                 pc.printf("Error: %u\n", diff);
00096             }
00097             
00098             bits = bits + 1 % 16;
00099             
00100             LPC_TIM2->IR |= (1 << 4);               // Clear IR by writing a one
00101                      
00102         }
00103         
00104 //        if (bits == 0) {
00105 //            
00106 //            for (int i = 0; i< 16; i++) {
00107 //                pc.printf("%u", (int) buffer[i]);
00108 //            }
00109 //            
00110 //            pc.printf("\n");
00111 //
00112 //        }
00113         
00114 //        // Poll CRO (rising edge) intterupt
00115 //        if (LCP_TIM2-IR != (1 << 5)) {
00116 //            
00117 //            int diff = (TIM2CR1 - TIM2CR2) % 0xFFFFFFFF;
00118 //
00119 //            // Do checks
00120 //            
00121 //            // End checks
00122 //            
00123 //            
00124 //            LCP_TIM2->IR &= ~(1 << 5);
00125 //        }
00126                 
00127     
00128     
00129     }
00130     
00131 }