FastPWM_LPC_SCT.cpp

00001 //For targets which use the SCT
00002 #if defined(TARGET_LPC81X) || defined(TARGET_LPC82X)
00003 
00004 #ifdef TARGET_LPC82X
00005 #define CTRL_U CTRL
00006 #endif
00007 
00008 #include "FastPWM.h"
00009 
00010 void FastPWM::initFastPWM( void ) {
00011     //Mbed uses the timer as a single unified 32-bit timer, who are we to argue with this, and it is easier
00012     bits = 32;
00013     
00014     #ifdef TARGET_LPC82X
00015     //The mbed lib uses the PWM peripheral slightly different, which is irritating. This sets it bck to the LPC81X
00016         _pwm.pwm->EVENT[_pwm.pwm_ch + 1].CTRL  = (1 << 12) | (_pwm.pwm_ch + 1);     // Event_n on Match_n 
00017         _pwm.pwm->EVENT[_pwm.pwm_ch + 1].STATE = 0xFFFFFFFF;                        // All states  
00018         _pwm.pwm->OUT[_pwm.pwm_ch].SET = (1 << 0);                                  // All PWM channels are SET on Event_0 
00019         _pwm.pwm->OUT[_pwm.pwm_ch].CLR = (1 << (_pwm.pwm_ch + 1));                  // PWM ch is CLRed on Event_(ch+1) 
00020     #endif
00021     
00022     //With 32-bit we fix prescaler to 1
00023     _pwm.pwm->CTRL_U |= (1 << 2) | (1 << 3);
00024     _pwm.pwm->CTRL_U &= ~(0x7F << 5);
00025     _pwm.pwm->CTRL_U &= ~(1 << 2);
00026 
00027 }
00028 
00029 void FastPWM::pulsewidth_ticks( uint32_t ticks ) {
00030     #ifdef TARGET_LPC81X
00031     _pwm.pwm->MATCHREL[_pwm.pwm_ch + 1].U = ticks;
00032     #else
00033     _pwm.pwm->MATCHREL[_pwm.pwm_ch + 1] = ticks;
00034     #endif
00035 }
00036 
00037 void FastPWM::period_ticks( uint32_t ticks ) {
00038     #ifdef TARGET_LPC81X
00039     _pwm.pwm->MATCHREL[0].U = ticks;
00040     #else
00041     _pwm.pwm->MATCHREL[0] = ticks;
00042     #endif
00043 }
00044 
00045 uint32_t FastPWM::getPeriod( void ) {
00046     #ifdef TARGET_LPC81X
00047     return _pwm.pwm->MATCHREL[0].U;
00048     #else
00049     return _pwm.pwm->MATCHREL[0];
00050     #endif
00051 }
00052 
00053 //Maybe implemented later, but needing to change the prescaler for a 32-bit
00054 //timer used in PWM mode is kinda unlikely.
00055 //If you really need to do it, rejoice, you can make it run so slow a period is over 40,000 year
00056 uint32_t FastPWM::setPrescaler(uint32_t reqScale) {
00057     //Disable dynamic prescaling
00058     dynamicPrescaler = false;
00059     
00060     return 1;
00061 }
00062 
00063 #endif