main.cpp

00001 // Phase-shifted PWM Test Code
00002 // 
00003 // Attempt to run two PWM outputs with 180° phase shifting
00004 // Version x.x
00005 // Created by Wayne Chin
00006 // October 15, 2010
00007 
00008 #include "mbed.h"
00009 
00010 #define TRUE 1
00011 #define FALSE 0
00012 
00013 DigitalOut led1(LED1);
00014 DigitalOut led2(LED2);
00015 DigitalOut led3(LED3);
00016 DigitalOut led4(LED4);
00017 
00018 Ticker pwmramp1;
00019 Ticker pwmramp2;
00020 int duty1; // Duty cycle in integer %
00021 int duty2; // Duty cycle in integer %
00022 int PWMclock; // PWM clock = system clock / 4
00023 int PWMrate; // Use to calculate PWM rate (period)
00024 
00025 Serial pc(USBTX, USBRX); // tx, rx
00026 
00027 void pwmupdate1()
00028 {
00029     int PWMwidth, PWMhalf, PWMrising, PWMfalling;
00030     if (duty1++ > 100) duty1 = 0; // Clamp at 100% pulsewidth
00031     PWMwidth = (duty1 * PWMrate) / 100;
00032     PWMhalf = PWMwidth / 2;
00033     PWMrising = PWMrate - PWMhalf;
00034     PWMfalling = PWMhalf;
00035     LPC_PWM1->MR3 = PWMrising; // Set rising edge
00036     LPC_PWM1->MR4 = PWMfalling; // Set falling edge
00037     LPC_PWM1->LER |= 0x18; // Enable PWM Match 3 & 4 latch
00038     led4 = !led4;
00039 }
00040 
00041 void pwmupdate2()
00042 {
00043     int PWMcenter, PWMwidth, PWMhalf, PWMrising, PWMfalling;
00044     if (duty2++ > 100) duty2 = 0; // Clamp at 100% pulsewidth
00045     PWMcenter = PWMrate / 2;
00046     PWMwidth = (duty2 * PWMrate) / 100;
00047     PWMhalf = PWMwidth / 2;
00048     PWMrising = PWMcenter - PWMhalf;
00049     PWMfalling = PWMcenter + PWMhalf;
00050     LPC_PWM1->MR5 = PWMrising;
00051     LPC_PWM1->MR6 = PWMfalling;
00052     LPC_PWM1->LER |= 0x60; // Enable PWM Match 5 & 6 latch
00053     led2 = !led2;
00054 }
00055 
00056 int main() 
00057 {
00058     /****** Program Starts Here *******/
00059     pc.baud(19200);
00060     pc.printf("\n\rConnected to mBed...\r\n");
00061     // Initialize variables
00062     duty1 = 0;
00063     duty2 = 0;
00064     
00065     printf("SystemCoreClock = %d Hz\r\n", SystemCoreClock);
00066     // Verify power control for peripherals register
00067     printf("PCLKSEL0: %x\n\r", LPC_SC->PCLKSEL0);          // Leave at CCLK/4
00068     PWMclock = SystemCoreClock / 4;
00069     PWMrate = PWMclock / 15000;                            // 15kHz
00070     printf("PWMrate: %x\n\r", PWMrate);
00071     //printf("PINSEL4: %x\n\r", LPC_PINCON->PINSEL4);        // Comes up as GPIO
00072     LPC_PINCON->PINSEL4 |= 0x00000040;                     // Set P2.3 for PWM1.4
00073     LPC_PINCON->PINSEL4 |= 0x00000400;                     // Set P2.5 for PWM1.6
00074     printf("PINSEL4: %x\n\r", LPC_PINCON->PINSEL4);
00075     // Set up count control register
00076     printf("PWM1CTCR: %x\n\r", LPC_PWM1->CTCR); // Should already come up in timer mode
00077     // Set up match control register
00078     printf("PWM1MCR: %x\n\r", LPC_PWM1->MCR);
00079     //LPC_PWM1->MCR |= 0x00002000; // Reset PWM4 on match - do not use
00080     //LPC_PWM1->MCR |= 0x00080000; // Reset PWM6 on match - do not use
00081     LPC_PWM1->MCR |= 0x00000002; // Reset PWM0 on match
00082     printf("PWM1MCR: %x\n\r", LPC_PWM1->MCR);
00083     // Set up match registers
00084     LPC_PWM1->MR0 = PWMrate; // Set MR0 (PWM rate)
00085     LPC_PWM1->MR3 = 0x000; // Reset MR3
00086     LPC_PWM1->MR4 = 0x320; // Reset MR4
00087     LPC_PWM1->MR5 = 0x160; // Reset MR5
00088     LPC_PWM1->MR6 = 0x480; // Reset MR6
00089     printf("PWM1MR0,3,4,5,6: %x %x %x %x %x\n\r", LPC_PWM1->MR0, LPC_PWM1->MR3, LPC_PWM1->MR4, LPC_PWM1->MR5, LPC_PWM1->MR6);
00090     // Set up latch enable register
00091     printf("PWM1LER: %x\n\r", LPC_PWM1->LER);
00092     LPC_PWM1->LER |= 0x08; // Enable PWM Match 3 latch
00093     LPC_PWM1->LER |= 0x10; // Enable PWM Match 4 latch
00094     LPC_PWM1->LER |= 0x20; // Enable PWM Match 5 latch
00095     LPC_PWM1->LER |= 0x40; // Enable PWM Match 6 latch
00096     printf("PWM1LER: %x\n\r", LPC_PWM1->LER);
00097     // Set up PWM control register
00098     printf("PWM1PCR: %x\n\r", LPC_PWM1->PCR);
00099     LPC_PWM1->PCR |= 0x00000010; // Select double edge PWM for PWM4
00100     LPC_PWM1->PCR |= 0x00000040; // Select double edge PWM for PWM6
00101     LPC_PWM1->PCR |= 0x00001000; // Enable PWM4
00102     LPC_PWM1->PCR |= 0x00004000; // Enable PWM6
00103     printf("PWM1PCR: %x\n\r", LPC_PWM1->PCR);
00104     // Set up timer control register
00105     printf("PWM1TCR: %x\n\r", LPC_PWM1->TCR);
00106     LPC_PWM1->TCR |= 0x08; // Enable PWM mode
00107     LPC_PWM1->TCR |= 0x01; // Enable counter
00108     printf("PWM1TCR: %x\n\r", LPC_PWM1->TCR);
00109 
00110     // Set up timeout calls
00111     pwmramp1.attach_us(&pwmupdate1, 250000); // setup pwmramp1 to call pwmupdate after 250 ms
00112     pwmramp2.attach_us(&pwmupdate2, 500000); // setup pwmramp2 to call pwmupdate after 500 ms
00113 
00114     while (1)
00115     {
00116         
00117     }//while
00118 }//main