Diff: lib_ClockCounter.cpp

Revision:

0:d3c997729db1

Child:

1:bdbac277828a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib_ClockCounter.cpp	Thu Nov 21 09:17:25 2019 +0000
@@ -0,0 +1,56 @@
+/** Mbed Library Clock Counter
+* Hardware pulse counter with TIMER2 (CAP2.0 or CAP2.1) on Mbed LPC1768
+*
+* Counts signal transitions on p30(CAP2.0) or p29(CAP2.1).
+* Can detecte rising, falling or both signal edge.
+* Return the signal edge count during a periode in seconds.
+* Shannon's theorem say with an input signal frequency up to 48 MHz with 96 MHz CCLK.
+* Only tested with frequencys up to 20 MHz and it work.
+*
+* Example :
+* @code
+* #include "mbed.h"
+* #include "lib_ClockCounter.h"
+*
+* Serial pc(USBTX, USBRX);
+* ClockCounter Frequency;
+* 
+* int main()
+* {
+*     while(1) pc.printf("Frequency = %d Hz\r\n", Frequency.getCount());
+* }
+* @endcode
+*/
+
+#include "lib_ClockCounter.h"
+
+ClockCounter::ClockCounter(PinName PIN_CAP2, edgeDetection EDGE)
+{
+    switch(PIN_CAP2)
+    {
+        case p30: case p29:
+                                                                    // PCONP => Power Mode Control register
+            LPC_SC->PCONP |= (0x1<<22);                             // Bit(22) 1 => Timer2 power on
+                                                                    // PCLKSEL1 => Peripheral Clock Selection register 1
+            LPC_SC->PCLKSEL1 |= (0x1<<12);                          // Bits(13,12) 01 => PCLK_TIMER2 = CCLK(96 MHz)
+                                                                    // TCR => Timer Control Register
+            LPC_TIM2->TCR = 0x0;                                    // Bits(1,0) 00 => Timer2 disabled
+                                                                    // PINSEL0 => Pin Function Select register 0
+            LPC_PINCON->PINSEL0 |= (0x3<<((PIN_CAP2==p30)?8:10));   // Bits(9,8) 11 => pin function CAP2.0 (p30), Bits(11,10) 11 => pin function CAP2.1 (p29)
+                                                                    // CTCR => Count Control Register
+            LPC_TIM2->CTCR = ((PIN_CAP2==p30)?0:4)+EDGE;            // Bits(3,2) 00 => CAP2.0 (p30 signal is counter clock) or 11 => CAP2.1 (p29 signal is counter clock), Bits(1,0) XX => timer is incremented on edge
+                                                                    // CCR => Capture Control Register
+            LPC_TIM2->CCR = 0x0;                                    // Bits(5,4,3,2,1,0) 000000 => capture and interrupt on event disabled
+        break;
+    }
+}
+
+int ClockCounter::getCount(float period)
+{
+                                                                    // TCR => Timer Control Register
+    LPC_TIM2->TCR = 0x2;                                            // Bits(1,0) 10 => Timer2 count reset
+    LPC_TIM2->TCR = 0x1;                                            // Bits(1,0) 01 => Timer2 enabled
+    wait(period);
+    LPC_TIM2->TCR = 0x0;                                            // Bits(1,0) 00 => Timer2 disabled
+    return LPC_TIM2->TC;                                            // TC => Timer Counter
+}
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