Neel Shah / Mbed 2 deprecated PWM_REG

Just tried to program the PWM register of LPC1768. The code has been well commented for use with LPC1768 based mBed

Dependencies:   mbed

main.cpp@0:0b19df35d533, 2013-02-03 (annotated)

Committer:
Neel
Date:
Sun Feb 03 21:08:53 2013 +0000
Revision:
0:0b19df35d533
PWM Register Level program

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Neel 0:0b19df35d533 1 #include "LPC17xx.h"
Neel 0:0b19df35d533 2 #include "mbed.h"
Neel 0:0b19df35d533 3
Neel 0:0b19df35d533 4 Serial pc(USBTX,USBRX);
Neel 0:0b19df35d533 5
Neel 0:0b19df35d533 6 int main()
Neel 0:0b19df35d533 7 {
Neel 0:0b19df35d533 8 // initialize the LED pins as outputs
Neel 0:0b19df35d533 9 //LPC_GPIO1->FIODIR = 1 << 18 | 1 << 27;
Neel 0:0b19df35d533 10 // PIN P26 is the output pin!
Neel 0:0b19df35d533 11 pc.printf("Welcome to LPC1768 PWM demo\n\r");
Neel 0:0b19df35d533 12 // ensure PWM peripheral is powered on (it is powered on by default)
Neel 0:0b19df35d533 13 LPC_SC->PCONP |= 1 << 6;
Neel 0:0b19df35d533 14 LPC_PWM1->TCR = 2; // bring PWM module into reset
Neel 0:0b19df35d533 15 LPC_PWM1->IR = 0xff; // clear any pending interrupts
Neel 0:0b19df35d533 16 // configure P2.0 for PWM1.1 - O - Pulse Width Modulator 1, channel 1 output.
Neel 0:0b19df35d533 17 LPC_PINCON->PINSEL4 = (LPC_PINCON->PINSEL4 & ~(0x3 << 0)) | (0x1 << 0);
Neel 0:0b19df35d533 18 // Disable pullups for P2.0
Neel 0:0b19df35d533 19 LPC_PINCON->PINMODE4 = (LPC_PINCON->PINMODE4 & ~0x3) | 0x2;
Neel 0:0b19df35d533 20 // Set prescale so we have a resolution of 1us
Neel 0:0b19df35d533 21 LPC_PWM1->PR = SystemCoreClock / (4 * 1000000) - 1;
Neel 0:0b19df35d533 22 LPC_PWM1->MR0 = 20000; // set the period in us. 50Hz rate
Neel 0:0b19df35d533 23 LPC_PWM1->MR1 = 1500; // set duty of 1.5ms
Neel 0:0b19df35d533 24 LPC_PWM1->MR2 = 19000; // set a match that occurs 1ms before the TC resets.
Neel 0:0b19df35d533 25 LPC_PWM1->LER = 0x07; // set latch-enable register
Neel 0:0b19df35d533 26 LPC_PWM1->MCR = 0x02 | (1 << 6); // reset on MR0, interrupt on MR2
Neel 0:0b19df35d533 27 LPC_PWM1->PCR = 1 << 9; // enable PWM1 with single-edge operation
Neel 0:0b19df35d533 28 LPC_PWM1->TCR = (1 << 3) | 1; // enable PWM mode and counting
Neel 0:0b19df35d533 29 while(1) {
Neel 0:0b19df35d533 30 // wait for MR2 interrupt flag to be raised
Neel 0:0b19df35d533 31 while((LPC_PWM1->IR & (1 << 2)) == 0);
Neel 0:0b19df35d533 32 LPC_PWM1->IR = 0xff; // clear interrupt flags
Neel 0:0b19df35d533 33 // write duty cycle value and set Latch-enable register
Neel 0:0b19df35d533 34 LPC_PWM1->MR1 = 10000; //from 200 = 1% and 20000 = 100%
Neel 0:0b19df35d533 35 LPC_PWM1->LER = 1 << 1;
Neel 0:0b19df35d533 36 }
Neel 0:0b19df35d533 37
Neel 0:0b19df35d533 38 }