Diff: main.cpp

Revision:

0:0d9b39b610c5

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Apr 20 21:09:27 2016 +0000
@@ -0,0 +1,81 @@
+// check pwm and 50us values for IRremote  IRremoteInt.h
+// CMT timer ch 39,  pin pg 196  CMT_IRO PTD7  on 2x4 RF header
+// derived from teensy 3 IRremote lib
+// https://forum.pjrc.com/threads/26331-IRRemote-issues?p=52316&viewfull=1#post52316
+
+#include "mbed.h"
+
+static uint32_t khz=40, CMT_PPS_VAL, fbus=60000000, cmd2=30, cmd4=19;
+DigitalOut led(LED1);
+
+volatile uint32_t ticks;
+
+extern "C" void CMT_IRQHandler() {
+     uint8_t tmp = CMT_MSC;  // reset interrupt
+     CMT_CMD2 = 30; 
+     led = !led; 
+     ticks++;
+}
+
+//  ref 39.7.3.1  30+1+19 = 50us period
+void init1() {
+    SIM_SCGC4 |= (1<<SIM_SCGC4_CMT_SHIFT);
+    CMT_PPS = CMT_PPS_VAL;    // 8 mhz
+    CMT_CGH1 = 1;
+    CMT_CGL1 = 1;
+    CMT_CMD1 = 0;
+    CMT_CMD2 = cmd2;    // mark low down counter  8-bit
+    CMT_CMD3 = 0;
+    CMT_CMD4 = cmd4;    // space low  period  8-bit
+    CMT_OC = 0;
+    CMT_MSC = 0x03;     // enable CMT and interrupt
+    NVIC_EnableIRQ(CMT_IRQn);
+}
+
+void init_pwm(int khz) {
+    SIM_SCGC4 |= (1<<SIM_SCGC4_CMT_SHIFT);
+    SIM_SOPT2 |= (1 << SIM_SOPT2_PTD7PAD_SHIFT);   // drive strength
+    CMT_PPS = CMT_PPS_VAL;    // 8 mhz
+    CMT_CGH1 = 2667 / khz;    // high time  30% duty  8-bit  ticks*.125us
+    CMT_CGL1 = 5333 / khz;    // low time
+    CMT_CMD1 = 0;
+    CMT_CMD2 = cmd2;              // no effect
+    CMT_CMD3 = 0;
+    CMT_CMD4 = 0;               // space low
+    CMT_OC = 0x60;     // enable IRO
+    CMT_MSC = 0x01; // enable
+
+    SIM_SCGC5 |= (1 << SIM_SCGC5_PORTD_SHIFT);  // power PORTD
+    PORTD_PCR7 = PORT_PCR_MUX(2)|(1<< PORT_PCR_DSE_SHIFT)|(1 << PORT_PCR_SRE_SHIFT);
+}
+
+main() {
+  // get F_BUS freq
+  fbus = SystemCoreClock / (((SIM->CLKDIV1 & SIM_CLKDIV1_OUTDIV2_MASK) >> SIM_CLKDIV1_OUTDIV2_SHIFT) + 1);
+  printf("\nSystemCoreClock %d  bus %d  %s %s\n",SystemCoreClock,fbus,__TIME__,__DATE__);
+  if (fbus == 48000000) CMT_PPS_VAL = 5 ;
+  else if (fbus == 24000000)CMT_PPS_VAL = 2 ;
+  else if (fbus == 16000000) CMT_PPS_VAL= 1 ;
+  else if (fbus ==  8000000)CMT_PPS_VAL = 0 ;
+  else if (fbus == 56000000)CMT_PPS_VAL = 6 ;
+  else if (fbus == 36000000) { CMT_PPS_VAL = 3 ; cmd4=25; khz=(32*khz)/36; }
+  else if (fbus == 60000000) { CMT_PPS_VAL = 6 ; cmd4=23; khz = (56*khz)/60; }
+  else if (fbus ==  4000000) { CMT_PPS_VAL = 0 ; cmd2=5;  khz=2*khz; }
+  else if (fbus ==  2000000) { CMT_PPS_VAL = 0 ; cmd2=5; cmd4=7; khz=4*khz; }
+
+
+#if 1
+  init_pwm(khz);    // pwm freq in khz
+  while(true) {
+      led= !led;
+      wait(1.0);
+  }
+#else
+    init1();      // 50us interrupts
+    while(true) {
+        printf("ticks %d\n",ticks);
+        wait(2.);
+    }
+#endif
+}
+