Neel Shah
Just tried to program the PWM register of LPC1768. The code has been well commented for use with LPC1768 based mBed
Revision 0:0b19df35d533, committed 2013-02-03
- Comitter:
- Neel
- Date:
- Sun Feb 03 21:08:53 2013 +0000
- Commit message:
- PWM Register Level program
Changed in this revision
| main.cpp | Show annotated file Show diff for this revision Revisions of this file |
| mbed.bld | Show annotated file Show diff for this revision Revisions of this file |
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Sun Feb 03 21:08:53 2013 +0000
@@ -0,0 +1,38 @@
+#include "LPC17xx.h"
+#include "mbed.h"
+
+Serial pc(USBTX,USBRX);
+
+int main()
+{
+ // initialize the LED pins as outputs
+ //LPC_GPIO1->FIODIR = 1 << 18 | 1 << 27;
+ // PIN P26 is the output pin!
+ pc.printf("Welcome to LPC1768 PWM demo\n\r");
+ // ensure PWM peripheral is powered on (it is powered on by default)
+ LPC_SC->PCONP |= 1 << 6;
+ LPC_PWM1->TCR = 2; // bring PWM module into reset
+ LPC_PWM1->IR = 0xff; // clear any pending interrupts
+ // configure P2.0 for PWM1.1 - O - Pulse Width Modulator 1, channel 1 output.
+ LPC_PINCON->PINSEL4 = (LPC_PINCON->PINSEL4 & ~(0x3 << 0)) | (0x1 << 0);
+ // Disable pullups for P2.0
+ LPC_PINCON->PINMODE4 = (LPC_PINCON->PINMODE4 & ~0x3) | 0x2;
+ // Set prescale so we have a resolution of 1us
+ LPC_PWM1->PR = SystemCoreClock / (4 * 1000000) - 1;
+ LPC_PWM1->MR0 = 20000; // set the period in us. 50Hz rate
+ LPC_PWM1->MR1 = 1500; // set duty of 1.5ms
+ LPC_PWM1->MR2 = 19000; // set a match that occurs 1ms before the TC resets.
+ LPC_PWM1->LER = 0x07; // set latch-enable register
+ LPC_PWM1->MCR = 0x02 | (1 << 6); // reset on MR0, interrupt on MR2
+ LPC_PWM1->PCR = 1 << 9; // enable PWM1 with single-edge operation
+ LPC_PWM1->TCR = (1 << 3) | 1; // enable PWM mode and counting
+ while(1) {
+ // wait for MR2 interrupt flag to be raised
+ while((LPC_PWM1->IR & (1 << 2)) == 0);
+ LPC_PWM1->IR = 0xff; // clear interrupt flags
+ // write duty cycle value and set Latch-enable register
+ LPC_PWM1->MR1 = 10000; //from 200 = 1% and 20000 = 100%
+ LPC_PWM1->LER = 1 << 1;
+ }
+
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Sun Feb 03 21:08:53 2013 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/cd19af002ccc \ No newline at end of file