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@elcojacobs
elcojacobs committed May 5, 2012
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372 changes: 372 additions & 0 deletions CShiftPWM.cpp
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/*
ShiftPWM.h - Library for Arduino to PWM many outputs using shift registers - Version 1
Copyright (c) 2011 Elco Jacobs, Technical University of Eindhoven, department of
Industrial Design, Electronics Atelier.
All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
---> See ShiftPWM.h for more info
*/

#include "CShiftPWM.h"
#if defined(ARDUINO) && ARDUINO >= 100
#include <Arduino.h>
#else
#include <WProgram.h>
#endif

#include "CShiftPWM.h"

extern const bool ShiftPWM_invertOutputs;

CShiftPWM::CShiftPWM(int timerInUse) : m_timer(timerInUse){ //Timer is set in initializer list, because it is const
m_ledFrequency = 0;
m_maxBrightness = 0;
m_amountOfRegisters = 0;
m_amountOfOutputs=0;
counter =0;

unsigned char * m_PWMValues=0;
}

CShiftPWM::~CShiftPWM() {
if(m_PWMValues>0){
free( m_PWMValues );
}
}

bool CShiftPWM::IsValidPin(int pin){
if(pin<m_amountOfOutputs){
return 1;
}
else{
Serial.print("Error: Trying to write duty cycle of pin ");
Serial.print(pin);
Serial.print(" , while number of outputs is ");
Serial.print(m_amountOfOutputs);
Serial.print(" , numbered 0-");
Serial.println(m_amountOfOutputs-1);
delay(1000);
return 0;
}
}


void CShiftPWM::SetOne(int pin, unsigned char value){
if(IsValidPin(pin) ){
m_PWMValues[pin]=value;
}
}

void CShiftPWM::SetAll(unsigned char value){
for(int k=0 ; k<(m_amountOfOutputs);k++){
m_PWMValues[k]=value;
}
}

void CShiftPWM::SetGroupOf2(int group, unsigned char v0,unsigned char v1){
if(IsValidPin(group*2+1) ){
m_PWMValues[group*2]=v0;
m_PWMValues[group*2+1]=v1;
}
}

void CShiftPWM::SetGroupOf3(int group, unsigned char v0,unsigned char v1,unsigned char v2){
if(IsValidPin(group*3+2) ){
m_PWMValues[group*3]=v0;
m_PWMValues[group*3+1]=v1;
m_PWMValues[group*3+2]=v2;
}
}

void CShiftPWM::SetGroupOf4(int group, unsigned char v0,unsigned char v1,unsigned char v2,unsigned char v3){
if(IsValidPin(group*4+3) ){
m_PWMValues[group*4]=v0;
m_PWMValues[group*4+1]=v1;
m_PWMValues[group*4+2]=v2;
m_PWMValues[group*4+3]=v3;
}
}

void CShiftPWM::SetGroupOf5(int group, unsigned char v0,unsigned char v1,unsigned char v2,unsigned char v3,unsigned char v4){
if(IsValidPin(group*5+4) ){
m_PWMValues[group*5]=v0;
m_PWMValues[group*5+1]=v1;
m_PWMValues[group*5+2]=v2;
m_PWMValues[group*5+3]=v3;
m_PWMValues[group*5+4]=v4;
}
}

// OneByOne functions are usefull for testing all your outputs
void CShiftPWM::OneByOneSlow(void){
OneByOne_core(1024/m_maxBrightness);
}

void CShiftPWM::OneByOneFast(void){
OneByOne_core(1);
}

void CShiftPWM::OneByOne_core(int delaytime){
int pin,brightness;
SetAll(0);
for(int pin=0;pin<m_amountOfOutputs;pin++){
for(brightness=0;brightness<m_maxBrightness;brightness++){
m_PWMValues[pin]=brightness;
delay(delaytime);
}
for(brightness=m_maxBrightness;brightness>=0;brightness--){
m_PWMValues[pin]=brightness;
delay(delaytime);
}
}
}

void CShiftPWM::SetAmountOfRegisters(unsigned char newAmount){
cli(); // Disable interrupt
unsigned char oldAmount = m_amountOfRegisters;
m_amountOfRegisters = newAmount;
m_amountOfOutputs=m_amountOfRegisters*8;

if(LoadNotTooHigh() ){ //Check if new amount will not result in deadlock
m_PWMValues = (unsigned char *) realloc(m_PWMValues, newAmount*8); //resize array for PWMValues

for(int k=oldAmount; k<(newAmount*8);k++){
m_PWMValues[k]=0; //set new values to zero
}
sei(); //Re-enable interrupt
}
else{
// New value would result in deadlock, keep old values and print an error message
m_amountOfRegisters = oldAmount;
m_amountOfOutputs=m_amountOfRegisters*8;
Serial.println("Amount of registers is not increased, because load would become too high");
sei();
}
}

bool CShiftPWM::LoadNotTooHigh(void){
// This function calculates if the interrupt load would become higher than 0.9 and prints an error if it would.
// This is with inverted outputs, which is worst case. Without inverting, it would be 42 per register.
float interruptDuration = 97+43* (float) m_amountOfRegisters;
float interruptFrequency = (float) m_ledFrequency* (float) m_maxBrightness;
float load = interruptDuration*interruptFrequency/F_CPU;

if(load > 0.9){
Serial.print("New interrupt duration ="); Serial.print(interruptDuration); Serial.println("clock cycles");
Serial.print("New interrupt frequency ="); Serial.print(interruptFrequency); Serial.println("Hz");
Serial.print("New interrupt load would be ");
Serial.print(load);
Serial.println(" , which is too high.");
return 0;
}
else{
return 1;
}

}

void CShiftPWM::Start(int ledFrequency, unsigned char maxBrightness){
// Configure and enable timer1 or timer 2 for a compare and match A interrupt.

m_ledFrequency = ledFrequency;
m_maxBrightness = maxBrightness;

if(LoadNotTooHigh() ){
if(m_timer==1){
InitTimer1();
}
else if(m_timer==2){
InitTimer2();
}
}
else{
Serial.println("Interrupts are disabled because load is too high.");
cli(); //Disable interrupts
}
}

void CShiftPWM::InitTimer1(void){
/* Configure timer1 in CTC mode: clear the timer on compare match
* See the Atmega328 Datasheet 15.9.2 for an explanation on CTC mode.
* See table 15-4 in the datasheet. */

bitSet(TCCR1B,WGM12);
bitClear(TCCR1B,WGM13);
bitClear(TCCR1A,WGM11);
bitClear(TCCR1A,WGM10);


/* Select clock source: internal I/O clock, without a prescaler
* This is the fastest possible clock source for the highest accuracy.
* See table 15-5 in the datasheet. */

bitSet(TCCR1B,CS10);
bitClear(TCCR1B,CS11);
bitClear(TCCR1B,CS12);

/* The timer will generate an interrupt when the value we load in OCR1A matches the timer value.
* One period of the timer, from 0 to OCR1A will therefore be (OCR1A+1)/(timer clock frequency).
* We want the frequency of the timer to be (LED frequency)*(number of brightness levels)
* So the value we want for OCR1A is: timer clock frequency/(LED frequency * number of bightness levels)-1 */
m_prescaler = 1;
OCR1A = round((float) F_CPU/((float) m_ledFrequency*((float) m_maxBrightness+1)))-1;
/* Finally enable the timer interrupt
/* See datasheet 15.11.8) */
bitSet(TIMSK1,OCIE1A);
}

void CShiftPWM::InitTimer2(void){
/* Configure timer2 in CTC mode: clear the timer on compare match
* See the Atmega328 Datasheet 15.9.2 for an explanation on CTC mode.
* See table 17-8 in the datasheet. */

bitClear(TCCR2B,WGM22);
bitSet(TCCR2A,WGM21);
bitClear(TCCR2A,WGM20);

/* Select clock source: internal I/O clock, calculate most suitable prescaler
* This is only an 8 bit timer, so choose the prescaler so that OCR2A fits in 8 bits.
* See table 15-5 in the datasheet. */
int compare_value = round((float) F_CPU/((float) m_ledFrequency*((float) m_maxBrightness+1))-1);
if(compare_value <= 255){
m_prescaler = 1;
bitClear(TCCR2B,CS22); bitClear(TCCR2B,CS21); bitClear(TCCR2B,CS20);
}
else if(compare_value/8 <=255){
m_prescaler = 8;
bitClear(TCCR2B,CS22); bitSet(TCCR2B,CS21); bitClear(TCCR2B,CS20);
}
else
if(compare_value/32 <=255){
m_prescaler = 32;
bitClear(TCCR2B,CS22); bitSet(TCCR2B,CS21); bitSet(TCCR2B,CS20);
}
else if(compare_value/64 <= 255){
m_prescaler = 64;
bitSet(TCCR2B,CS22); bitClear(TCCR2B,CS21); bitClear(TCCR2B,CS20);
}
else if(compare_value/128 <= 255){
m_prescaler = 128;
bitSet(TCCR2B,CS22); bitClear(TCCR2B,CS21); bitSet(TCCR2B,CS20);
}
else if(compare_value/256 <= 255){
m_prescaler = 256;
bitSet(TCCR2B,CS22); bitSet(TCCR2B,CS21); bitClear(TCCR2B,CS20);
}

/* The timer will generate an interrupt when the value we load in OCR2A matches the timer value.
* One period of the timer, from 0 to OCR2A will therefore be (OCR2A+1)/(timer clock frequency).
* We want the frequency of the timer to be (LED frequency)*(number of brightness levels)
* So the value we want for OCR2A is: timer clock frequency/(LED frequency * number of bightness levels)-1 */
OCR2A = round( ( (float) F_CPU / (float) m_prescaler ) / ( (float) m_ledFrequency*( (float) m_maxBrightness+1) ) -1);
/* Finally enable the timer interrupt
/* See datasheet 15.11.8) */
bitSet(TIMSK2,OCIE2A);
}


void CShiftPWM::PrintInterruptLoad(void){
//This function prints information on the interrupt settings for ShiftPWM
//It runs a delay loop 2 times: once with interrupts enabled, once disabled.
//From the difference in duration, it can calculate the load of the interrupt on the program.

unsigned long start1,end1,time1,start2,end2,time2,k;
double load, cycles_per_int, interrupt_frequency;


if(m_timer==1){
if(TIMSK1 & (1<<OCIE1A)){
// interrupt is enabled, continue
}
else{
// interrupt is disabled
Serial.println("Interrupt is disabled.");
return;
}
}
else if(m_timer==2){
if(TIMSK2 & (1<<OCIE2A)){
// interrupt is enabled, continue
}
else{
// interrupt is disabled
Serial.println("Interrupt is disabled.");
return;
}
}

//run with interrupt enabled
start1 = micros();
for(k=0; k<100000; k++){
delayMicroseconds(1);
}
end1 = micros();
time1 = end1-start1;

//Disable Interrupt
if(m_timer==1){
bitClear(TIMSK1,OCIE1A);
}
else if(m_timer==2){
bitClear(TIMSK2,OCIE2A);
}


// run with interrupt disabled
start2 = micros();
for(k=0; k<100000; k++){
delayMicroseconds(1);
}
end2 = micros();
time2 = end2-start2;

// ready for calculations
load = (double)(time1-time2)/(double)(time1);
if(m_timer==1){
interrupt_frequency = (F_CPU/m_prescaler)/(OCR1A+1);
}
else if(m_timer==2){
interrupt_frequency = (F_CPU/m_prescaler)/(OCR2A+1);
}
cycles_per_int = load*(F_CPU/interrupt_frequency);

//Ready to print information
Serial.print("Load of interrupt: "); Serial.println(load,10);
Serial.print("Clock cycles per interrupt: "); Serial.println(cycles_per_int);
Serial.print("Interrupt frequency: "); Serial.print(interrupt_frequency); Serial.println(" Hz");
Serial.print("PWM frequency: "); Serial.print(interrupt_frequency/(m_maxBrightness+1)); Serial.println(" Hz");

if(m_timer==1){
Serial.println("Timer1 in use for highest precision.");
Serial.println("Include servo.h to use timer2.");
Serial.print("OCR1A: "); Serial.println(OCR1A, DEC);
Serial.print("Prescaler: "); Serial.println(m_prescaler);

//Re-enable Interrupt
bitSet(TIMSK1,OCIE1A);
}
else if(m_timer==2){
Serial.println("Timer2 in use, because Timer1 is used by servo library.");
Serial.print("OCR2A: "); Serial.println(OCR2A, DEC);
Serial.print("Presclaler: "); Serial.println(m_prescaler);

//Re-enable Interrupt
bitSet(TIMSK2,OCIE2A);
}
}

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