LPC800-MAX RGB demo using SCT and MRT
LPC800-MAX RGB demo using State-Configurable Timer(SCT) and Multi-Rate Timer(MRT).
http://www.youtube.com/watch?v=PABxoWZB0YM
Diff: SCT_PWM.cpp
- Revision:
- 1:4e19f154ec21
diff -r f86c572491c3 -r 4e19f154ec21 SCT_PWM.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/SCT_PWM.cpp Mon Oct 14 03:59:30 2013 +0000 @@ -0,0 +1,99 @@ +#include "SCT_PWM.h" + +#define BIT_ON(A) (1<<A) + +// http://www.lpcware.com/content/nxpfile/lpc80-sct-cookbook-and-tutorial-code-examples + +SCT_PWM::SCT_PWM(int pin, int channel) : ch(channel) +{ + static bool insted = false; + + if (!insted) { + inst(); + insted = true; + } + swm(pin); + + LPC_SCT->EVENT[ch + 1].STATE = LPC_SCT->EVENT[0].STATE; + LPC_SCT->EVENT[ch + 1].CTRL = LPC_SCT->EVENT[0].CTRL | (ch+1)<<0; // match 1...5 + + LPC_SCT->OUT[ch].SET = BIT_ON(0); // event 0 + LPC_SCT->OUT[ch].CLR = BIT_ON(ch+1); // event 1...5 +} + +void SCT_PWM::inst() +{ + LPC_SYSCON->SYSAHBCLKCTRL |= (1<<8); // enable SCT + LPC_SYSCON->PRESETCTRL |= (1<<8); // reset SCT + + LPC_SCT->EVENT[0].STATE = BIT_ON(0); // state 0 + LPC_SCT->EVENT[0].CTRL = (1<<12) | (1<<14); + + LPC_SCT->LIMIT_L |= BIT_ON(0); // event 0 + + LPC_SCT->CONFIG |= (1<<0) | (1<<17); // unify, auto limit + LPC_SCT->CTRL_L |= (SystemCoreClock/1000000-1)<<5; // set prescaler, SCT clock = 1 MHz + + LPC_SCT->CTRL_L &= ~(1<<2); // unhalt it by clearing bit 2 of CTRL reg +} + +void SCT_PWM::swm(int pin) +{ + switch(ch) { + case 0: // CTOUT_0 + LPC_SWM->PINASSIGN6 = (LPC_SWM->PINASSIGN6 & 0x00ffffff) | pin<<24; + break; + case 1: // CTOUT_1 + LPC_SWM->PINASSIGN7 = (LPC_SWM->PINASSIGN7 & 0xffffff00) | pin<<0; + break; + case 2: // CTOUT_2 + LPC_SWM->PINASSIGN7 = (LPC_SWM->PINASSIGN7 & 0xffff00ff) | pin<<8; + break; + case 3: // CTOUT_3 + LPC_SWM->PINASSIGN7 = (LPC_SWM->PINASSIGN7 & 0xff00ffff) | pin<<16; + break; + } +} + +void SCT_PWM::period(float seconds) +{ + period_us(seconds * 1000000); +} + +void SCT_PWM::period_ms(int ms) +{ + period_us(ms * 1000); +} + +void SCT_PWM::period_us(int us) +{ + LPC_SCT->MATCHREL[0].U = us - 1; +} + +void SCT_PWM::pulsewidth(float seconds) +{ + pulsewidth_us(seconds * 1000000); +} + +void SCT_PWM::pulsewidth_ms(int ms) +{ + pulsewidth_us(ms * 1000); +} + +void SCT_PWM::pulsewidth_us(int us) +{ + LPC_SCT->MATCHREL[ch + 1].U = us; +} + +void SCT_PWM::write(float value) +{ + LPC_SCT->MATCHREL[ch + 1].U = value * LPC_SCT->MATCHREL[0].U; +} + +float SCT_PWM::read() +{ + if (LPC_SCT->MATCHREL[0].U == 0) { + return 0.0; + } + return (float)LPC_SCT->MATCHREL[ch + 1].U / LPC_SCT->MATCHREL[0].U; +}