TimerCapture.cpp

00001 #include "TimerCapture.h"
00002 
00003 bool TimerCapture::timerStarted = false;
00004 
00005 TimerCapture::TimerCapture(PinName pCapturePin) {
00006     uint8_t bitcount_pinselect = 0;
00007     uint8_t bitcount_capture_control = 0;
00008     
00009     #if DEBUG
00010     printf("Entering ctor\r\n");
00011     #endif
00012     
00013     switch (pCapturePin) {
00014         case p30:
00015             bitcount_pinselect = 8;
00016             bitcount_capture_control = 0;
00017             break;
00018         case p29:
00019             bitcount_pinselect = 10;
00020             bitcount_capture_control = 3;
00021             break;
00022         default:
00023             error("TimerCapture: Invalid pin specified! Pick either p29 (P0.5) or p30 (p0.4).");
00024             break;
00025     }
00026     
00027     #if DEBUG
00028     printf("Bitcounts selected: %d (pinselect) %d (capture control)\r\n", bitcount_pinselect, bitcount_capture_control);
00029     #endif
00030     
00031     uint32_t bitmask_pinselect = (0x3 << bitcount_pinselect);
00032     mCapturePin = pCapturePin;
00033     
00034     // error out if the pin is already configured.
00035     if ((LPC_PINCON->PINSEL0 & bitmask_pinselect) == bitmask_pinselect) {
00036         error("TimerCapture: Pin is already configured!");
00037     }
00038     
00039     
00040     //check if peripheral has power, else this operation will hang!
00041     if ((LPC_SC->PCONP & (1 << 22)) == 0) {
00042         error("TimerCapture: Attempted to write to timer registers with power off!");
00043     }
00044     
00045     #if DEBUG
00046     printf("OK to configure registers\r\n");
00047     #endif
00048     
00049     // configure the pin
00050     LPC_PINCON->PINSEL0 |= bitmask_pinselect;
00051     
00052     #if DEBUG
00053     printf("Configuring rising edge. Register is %08x\r\n", LPC_TIM2->CCR);
00054     #endif
00055     
00056     // store on rising edge of input
00057     LPC_TIM2->CCR |= (1 << bitcount_capture_control); 
00058     
00059     #if DEBUG
00060     printf("Leaving ctor\r\n");
00061     #endif
00062 }
00063 
00064 void TimerCapture::startTimer() {
00065     if (!timerStarted) {
00066         timerStarted = true;
00067         
00068         configureTimer();
00069         
00070         //start timer
00071         LPC_TIM2->TCR = 1;
00072     }
00073 }
00074 
00075 void TimerCapture::stopTimer() {
00076     timerStarted = false;
00077     //stop timer
00078     LPC_TIM2->TCR = 0;
00079 }
00080 
00081 bool TimerCapture::isRunning() {
00082     return timerStarted;
00083 }
00084 
00085 void TimerCapture::resetTimer() {
00086     //reset timer
00087     LPC_TIM2->TCR = 2;
00088     LPC_TIM2->TCR = 0;
00089     LPC_TIM2->CR0 = 0;
00090     LPC_TIM2->CR1 = 0;
00091 }
00092 
00093 uint32_t TimerCapture::getTime() {
00094     uint32_t observedTime = 0;
00095     switch(mCapturePin) {
00096         case p30:
00097             observedTime = LPC_TIM2->CR0;
00098             break;
00099         case p29:
00100             observedTime = LPC_TIM2->CR1;
00101             break;
00102         default:
00103             observedTime = 0;
00104             break;
00105     }
00106     
00107     return observedTime;
00108 }
00109 
00110 void TimerCapture::configureTimer() {
00111     // Power on Peripheral TIMER2
00112     LPC_SC->PCONP |= (1 << 22);
00113     
00114     // Set clock source for TIMER2
00115     uint8_t clockSel = 0x01;
00116     LPC_SC->PCLKSEL1 |= (clockSel << 12);
00117     
00118     // Set prescaler counter
00119     LPC_TIM2->PR = SystemCoreClock/1000; //should increment once a milisecond.
00120     
00121 }
00122