Diff: Timer2.cpp

Revision:

0:e619b6823668

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Timer2.cpp	Tue Jan 28 17:01:19 2014 +0000
@@ -0,0 +1,53 @@
+
+/*
+    This counter establishes the measurent interval.
+    MAT2.0 (P8) is set when the interval has elapsed.
+
+    This code generates timed intervals T = <prescale> * 100 ms.
+    mbed pin 8 goes high at the beginning of the interval and returns to zero at the end.
+    The interrupt occurs at the end of the interval.
+*/
+#include "TARGET_LPC1768/LPC17xx.h"
+#include "mbed.h"
+#include "Timer2.h"
+
+funcptr timer2ISR;
+
+void Timer2_IRQHandler(void)
+{
+    if (LPC_TIM2->IR & 1)           // MR0 interrupt
+    {
+        LPC_TIM2->IR = 1;           // clear the interrupt
+        if (timer2ISR)
+            timer2ISR();
+    }
+}
+
+void Timer2_init(funcptr callback)
+{
+    timer2ISR = callback;
+    LPC_SC->PCONP |= (1<<22);           // Power on the Timer2
+    LPC_SC->PCLKSEL1 &= ~(3<<12);
+    LPC_SC->PCLKSEL1 |= (1<<12);        // Select  CCLK for Timer2
+    LPC_PINCON->PINSEL0 &=~(3<<12);
+    LPC_PINCON->PINSEL0 |= (3<<12);     // Connect MAT2.0 to mbed P8
+    LPC_PINCON->PINMODE0 &=~(3<<12);
+    LPC_PINCON->PINMODE0 |= (2<<12);    // no pull-p or pull-down
+    if (callback)
+    {
+        NVIC_SetPriority(TIMER2_IRQn, 10);
+        NVIC_SetVector(TIMER2_IRQn, (uint32_t)&Timer2_IRQHandler);
+        NVIC_EnableIRQ(TIMER2_IRQn);
+    }
+}
+void Timer2_start(int prescale)
+{
+    LPC_TIM2->TCR = 2;                  // Reset the timer and prescale counters on next PCLK
+    LPC_TIM2->MR0 = CLOCK/10;           // Set the Timer2 match register for 100 ms resolution
+    LPC_TIM2->CTCR = 0;                 // Timer2 is incremented when the prescale register == 0
+    LPC_TIM2->PR = prescale;            // Update prescale register
+    LPC_TIM2->MCR = 3;                  // Interrupt on MR0 and reset
+    LPC_TIM2->EMR = (3<<4)|1;           // Toggle MAT2.0 when match occurs.
+    LPC_TIM2->TCR = 1;                  // Enable Timer2
+    LPC_TIM3->TCR = 1;                  // Enable Timer3
+}