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This commit is contained in:
Asbelos 2021-01-26 09:04:09 +00:00
parent 13e516f8b2
commit a4b63013ba
4 changed files with 8 additions and 534 deletions
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10
DCCTimer.cpp
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@ -28,7 +28,7 @@
*/ */
#include "DCCTimer.h" #include "DCCTimer.h"
#include "DIAG.h"
const int DCC_SIGNAL_TIME=58; // this is the 58uS DCC 1-bit waveform half-cycle const int DCC_SIGNAL_TIME=58; // this is the 58uS DCC 1-bit waveform half-cycle
const int DCC_SLOW_TIME=58*512; // for <D DCC SLOW> command diagnostics const int DCC_SLOW_TIME=58*512; // for <D DCC SLOW> command diagnostics
@ -38,20 +38,24 @@ INTERRUPT_CALLBACK interruptHandler=0;
void DCCTimer::begin(INTERRUPT_CALLBACK callback, bool slow) { void DCCTimer::begin(INTERRUPT_CALLBACK callback, bool slow) {
interruptHandler=callback; interruptHandler=callback;
// Initialise timer1 to trigger every 58us (DCC_SIGNAL_TIME) // Initialise timer1 to trigger every 58us (DCC_SIGNAL_TIME)
long clockCycles=((F_CPU / 1000000) * (slow? DCC_SLOW_TIME : DCC_SIGNAL_TIME)) >>1;
noInterrupts(); noInterrupts();
#ifdef ARDUINO_ARCH_MEGAAVR #ifdef ARDUINO_ARCH_MEGAAVR
// Arduino unoWifi Rev2 and nanoEvery architectire // Arduino unoWifi Rev2 and nanoEvery architectire
long clockCycles=slow? (14*512) : 14; // guesswork!!!!
DIAG(F("\nTimer unoWifi/nanoEvery F_CPU=%l c=%d"),F_CPU,clockCycles);
TCB0.CCMP = clockCycles; TCB0.CCMP = clockCycles;
TCB0.INTFLAGS = TCB_CAPT_bm; // clear interrupt request flag TCB0.INTFLAGS = TCB_CAPT_bm; // clear interrupt request flag
TCB0.INTCTRL = TCB_CAPT_bm; // Enable the interrupt TCB0.INTCTRL = TCB_CAPT_bm; // Enable the interrupt
TCB0.CNT = 0; TCB0.CNT = 0;
TCB0.CTRLA |= TCB_ENABLE_bm; // start TCB0.CTRLA |= TCB_ENABLE_bm; // start
#define ISR_NAME TCB2_INT_vect #define ISR_NAME TCB0_INT_vect
#else #else
// Arduino nano, uno, mega // Arduino nano, uno, mega
long clockCycles=((F_CPU / 1000000) * (slow? DCC_SLOW_TIME : DCC_SIGNAL_TIME)) >>1;
DIAG(F("\nTimer nano/uno/mega F_CPU=%l c=%d"),F_CPU,clockCycles);
TCCR1A = 0; TCCR1A = 0;
ICR1 = clockCycles; ICR1 = clockCycles;
TCNT1 = 0; TCNT1 = 0;

14
EveryTimerB.cpp
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@ -1,14 +0,0 @@
#ifdef ARDUINO_ARCH_MEGAAVR
#include "EveryTimerB.h"
void EveryTimerB::isrDefaultUnused(void) {}
// code timer B2. For B0 and B1 copy this code and change the '2' to '0' and '1'
EveryTimerB TimerB2;
ISR(TCB2_INT_vect)
{
TimerB2.next_tick();
TCB2.INTFLAGS = TCB_CAPT_bm;
}
#endif // ARDUINO_ARCH_MEGAAVR

390
EveryTimerB.h
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@ -1,390 +0,0 @@
// EveryTimerB library.
// by Kees van der Oord Kees.van.der.Oord@inter.nl.net
// Timer library for the TCB timer of the AtMega4809 processor.
// tested on the Arduino Nano Every (AtMega4809) and the Arduino 1.8.12 IDE
// support for the Every is the 'Arduino MegaAVR' boards module (Tools | Board | Boards Manager)
// usage:
/*
#ifdef ARDUINO_ARCH_MEGAAVR
#include "EveryTimerB.h"
#define Timer1 TimerB2 // use TimerB2 as a drop in replacement for Timer1
#else // assume architecture supported by TimerOne library ....
#include "TimerOne.h"
#endif
// code below will now work both on the MegaAVR and AVR processors
void setup() {
Timer1.initialize();
Timer1.attachInterrupt(myisr);
Timer1.setPeriod(1000000UL); // like the TimerOne library this will start the timer as well
}
void myisr() {
// do something useful every second
}
*/
// clock source options:
// The TCB clock source is specified in the initialize() function with default value EveryTimerB_CLOCMODE.
// define this macro before including this file to use a different default clock mode
// e.g.:
// #define EveryTimerB_CLOCMODE TCB_CLKSEL_CLKTCA_gc // 250 kHz ~ 4 us
// #define EveryTimerB_CLOCMODE TCB_CLKSEL_CLKDIV2_gc // 8 MHz ~ 0.125 us
// #define EveryTimerB_CLOCMODE TCB_CLKSEL_CLKDIV_gc // 16 MHz ~ 0.0625 us
// timer options
// The 4809 has one A timer (TCA) and four B timers (TCB).
// TCA and TCB3 are used by the arduino core to generate the clock used by millis() and micros().
// TCB0 generates the PWM timing for pin D6, TCB1 for pin D3.
// By default Timer Control B2 is defined as TimerB2 in the EveryTimerB library.
// If you would like to use the TCB0 and TCB1 as well you have to copy the code
// from the EveryTimerB.cpp into your product file and adapt for B0 and B1 timers.
//
// for information on the 4809 TCA and TCB timers:
// http://ww1.microchip.com/downloads/en/AppNotes/TB3217-Getting-Started-with-TCA-90003217A.pdf
// http://ww1.microchip.com/downloads/en/Appnotes/TB3214-Getting-Started-with-TCB-90003214A.pdf
// %LOCALAPPDATA%\Arduino15\packages\arduino\hardware\megaavr\1.8.5\cores\arduino\wiring.c
// %LOCALAPPDATA%\Arduino15\packages\arduino\hardware\megaavr\1.8.5\variants\nona4809\variant.c
// %LOCALAPPDATA%\Arduino15\packages\arduino\tools\avr-gcc\7.3.0-atmel3.6.1-arduino5\avr\include\avr\iom4809.h
// 20 MHz system clock
// to run the Every at 20 MHz, add the lines below to the nona4809 section of the boards.txt file
// in %LOCALAPPDATA%\Arduino15\packages\arduino\hardware\megaavr\1.8.5.
// they add the sub menu 'Tools | Clock' to choose between 16MHz and 20MHz.
/*
menu.clock=Clock
nona4809.menu.clock.16internal=16MHz
nona4809.menu.clock.16internal.build.f_cpu=16000000L
nona4809.menu.clock.16internal.bootloader.OSCCFG=0x01
nona4809.menu.clock.20internal=20MHz
nona4809.menu.clock.20internal.build.f_cpu=20000000L
nona4809.menu.clock.20internal.bootloader.OSCCFG=0x02
*/
// On 20Mhz, the 1.8.12 IDE MegaAvr core library implementation
// of the millis() and micros() functions is not accurate.
// the file "MegaAvr20MHz.h" implements a quick hack to correct for this
//
// to do:
// there is no range check on the 'period' arguments of setPeriod ...
// check if it is necessary to set the CNT register to 0 in start()
#ifndef EveryTimerB_h_
#define EveryTimerB_h_
#ifdef ARDUINO_ARCH_MEGAAVR
#ifndef EveryTimerB_CLOCMODE
#define EveryTimerB_CLOCMODE TCB_CLKSEL_CLKTCA_gc
#endif
#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif
#include "MegaAvr20MHz.h"
#include "pins_arduino.h"
#define TCB_RESOLUTION 65536UL // TCB is 16 bit
// CLOCK F_CPU DIV TICK OVERFLOW OVERFLOW/s
// CLKTCA 16MHz 64 4000 ns 262144us 3.8 Hz
// CLKDIV2 16MHz 2 125 ns 8192us 122 Hz
// CLKDIV1 16MHz 1 62.5ns 4096us 244 Hz
// CLKTCA 20MHz 64 3200 ns 209716us 4.8 Hz
// CLKDIV2 20MHz 2 100 ns 6554us 153 Hz
// CLKDIV1 20MHz 1 50 ns 3277us 305 Hz
class EveryTimerB
{
public:
// The AtMega Timer Control B clock sources selection:
// TCB_CLKSEL_CLKTCA_gc, // Timer Controller A, Arduino framework sets TCA to F_CPU/64 = 250kHz (4us) @ 16MHz or 312.5kHz (3.2us) @ 20MHz
// TCB_CLKSEL_CLKDIV2_gc, // CLK_PER/2 Peripheral Clock / 2: 8MHz @ 16Mhz or 10MHz @ 20MHz
// TCB_CLKSEL_CLKDIV1_gc // CLK_PER Peripheral Clock: 16MHz @ 16Mhz or 20MHz @ 20MHz
// intialize: sets the timer compare mode and the clock source
void initialize(TCB_t * timer_ = &TCB2, TCB_CLKSEL_t clockSource = EveryTimerB_CLOCMODE, unsigned long period = 1000000UL) __attribute__((always_inline)) {
timer = timer_;
#if defined(MegaAvr20MHzCorrected)
corrected20MHzInit(); // see commment in MegaAvr20MHz_h
#endif
stop();
timer->CTRLB = TCB_CNTMODE_INT_gc & ~TCB_CCMPEN_bm; // timer compare mode with output disabled
if(clockSource) setClockSource(clockSource);
if(period) setPeriod(period);
}
void setClockSource(TCB_CLKSEL_t clockSource) __attribute__((always_inline)) {
timer->CTRLA = clockSource; // this stops the clock as well ...
switch(clockSource) {
#if F_CPU == 20000000UL
case TCB_CLKSEL_CLKTCA_gc: maxTimeWithoutOverflow = 209715; break; // (TCB_RESOLUTION * 64) / 20
case TCB_CLKSEL_CLKDIV2_gc: maxTimeWithoutOverflow = 6553; break; // (TCB_RESOLUTION * 2) / 20
case TCB_CLKSEL_CLKDIV1_gc: maxTimeWithoutOverflow = 3276; break; // (TCB_RESOLUTION * 1) / 20
#else
case TCB_CLKSEL_CLKTCA_gc: maxTimeWithoutOverflow = 262144; break;
case TCB_CLKSEL_CLKDIV2_gc: maxTimeWithoutOverflow = 8192; break;
case TCB_CLKSEL_CLKDIV1_gc: maxTimeWithoutOverflow = 4096; break;
#endif
}
}
TCB_CLKSEL_t getClockSource() {
return (TCB_CLKSEL_t)(timer->CTRLA & (TCB_CLKSEL_CLKTCA_gc|TCB_CLKSEL_CLKDIV2_gc|TCB_CLKSEL_CLKDIV1_gc));
}
double getFrequencyOfClock(TCB_CLKSEL_t clock) {
switch(clock) {
// suppose nobody touched the default TCA configuration ...
case TCB_CLKSEL_CLKTCA_gc: return double(F_CPU/64); break;
case TCB_CLKSEL_CLKDIV2_gc: return double(F_CPU/2); break;
case TCB_CLKSEL_CLKDIV1_gc: return double(F_CPU); break;
}
return 0.0;
}
double getClockFrequency() {
return getFrequencyOfClock(getClockSource());
}
// setPeriod: sets the period
// note: max and min values are different for each clock
// CLKTCA: conversion from us to ticks multiplies 'period' first with 10, so max value is MAX_ULONG/10 ~ 1 hr 11 minutes 34 seconds
// CLKDIV2: conversion from us to ticks is a *10 multiplication, so max value is 420M us (~ 7 minutes)
// CLKDIV1: conversion from us to ticks is a *20 multiplication, so max value is 210M us (~ 3.5 minutes)
void setPeriod(unsigned long period /* us */) __attribute__((always_inline)) {
timer->CTRLA &= ~TCB_ENABLE_bm;
// conversion from us to ticks depends on the clock
switch(timer->CTRLA & TCB_CLKSEL_gm)
{
case TCB_CLKSEL_CLKTCA_gc:
#if F_CPU == 20000000UL
period = (period * 10) / 32; // 20Mhz / 64x clock divider of TCA => 3.2 us / tick
#else // 16000000UL
period /= 4; // 16MHz / 64x clock divider of TCA => 4 us / tock
#endif
break;
case TCB_CLKSEL_CLKDIV2_gc:
#if F_CPU == 20000000UL
period *= 10; // 20MHz / 2x clock divider => 10 ticks / us
#else // 16000000UL
period *= 8; // 16MHz / 2x clock divider => 8 ticks / us
#endif
break;
case TCB_CLKSEL_CLKDIV1_gc:
#if F_CPU == 20000000UL
period *= 20; // 20MHz: 20 ticks / us
#else // 16000000UL
period *= 16; // 16MHz: 16 ticks / u3
#endif
break;
}
// to support longer than TCB_RESOLUTION ticks,
// this class supports first waiting for N 'overflowCounts'
// and next program the timer the remaining 'remainder' ticks:
countsPerOverflow = TCB_RESOLUTION;
overflowCounts = period / TCB_RESOLUTION;
remainder = period % TCB_RESOLUTION;
// the timer period is always one tick longer than programmed,
// so a remainder of 1 is not possible. reduce the length of
// the 'overflow' cycles to get a remainder that is not 1
if(overflowCounts) {
while(remainder == 1) {
--countsPerOverflow;
overflowCounts = period / countsPerOverflow;
remainder = period % countsPerOverflow;
}
}
// the timer period is always one tick longer than programmed
--countsPerOverflow;
if(remainder) --remainder;
// let's go
start();
}
void start() __attribute__((always_inline)) {
stop();
overflowCounter = overflowCounts;
timer->CCMP = overflowCounts ? countsPerOverflow : remainder;
timer->CNT = 0;
timer->CTRLA |= TCB_ENABLE_bm;
}
void stop() __attribute__((always_inline)) {
timer->CTRLA &= ~TCB_ENABLE_bm;
timer->INTFLAGS = TCB_CAPT_bm; // writing to the INTFLAGS register will clear the interrupt request flag
}
bool isEnabled(void) __attribute__((always_inline)) {
return timer->CTRLA & TCB_ENABLE_bm ? true : false;
}
void enable(void) __attribute__((always_inline)) {
timer->CTRLA |= TCB_ENABLE_bm;
}
bool disable(void) __attribute__((always_inline)) {
timer->CTRLA &= ~TCB_ENABLE_bm;
}
void attachInterrupt(void (*isr)()) __attribute__((always_inline)) {
isrCallback = isr;
timer->INTFLAGS = TCB_CAPT_bm; // clear interrupt request flag
timer->INTCTRL = TCB_CAPT_bm; // Enable the interrupt
}
void attachInterrupt(void (*isr)(), unsigned long microseconds) __attribute__((always_inline)) {
if(microseconds > 0) stop();
attachInterrupt(isr);
if (microseconds > 0) setPeriod(microseconds);
}
void detachInterrupt() __attribute__((always_inline)) {
timer->INTCTRL &= ~TCB_CAPT_bm; // Disable the interrupt
isrCallback = isrDefaultUnused;
}
void enableInterrupt() __attribute__((always_inline)) {
timer->INTFLAGS = TCB_CAPT_bm; // clear interrupt request flag
timer->INTCTRL = TCB_CAPT_bm; // Enable the interrupt
}
void disableInterrupt() __attribute__((always_inline)) {
timer->INTCTRL &= ~TCB_CAPT_bm; // Enable the interrupt
}
TCB_CNTMODE_enum getMode() __attribute__((always_inline)) {
return (TCB_CNTMODE_enum) (timer->CTRLB & 0x7);
}
void setMode(TCB_CNTMODE_enum mode) __attribute__((always_inline)) {
timer->CTRLB = (timer->CTRLB & ~0x7) | mode;
}
uint8_t isOutputEnabled() __attribute__((always_inline)) {
return timer->CTRLB & TCB_CCMPEN_bm;
}
uint8_t enableOutput() __attribute__((always_inline)) {
timer->CTRLB |= TCB_CCMPEN_bm;
}
uint8_t disableOutput() __attribute__((always_inline)) {
timer->CTRLB &= ~TCB_CCMPEN_bm;
}
// this will start PWM on pin 6 (TCB0) or pin 3 (TCB1)
// set the pins to output with setMode(x,OUTPUT) before calling this function
// period determines the clock ticks in one cycle:
// 16MHz clock: slowest frequency at 255 = 62 kHz.
// 8MHz clock: slowest frequency at 255 = 31 kHz.
// 256kHz clock: slowest frequency at 255 = 1 kHz.
// compare determines the duty cycle.
// with a period of 255, set the compare to 128 to get 50% duty cycle.
void setPwmMode(byte period, byte compare) {
disableInterrupt();
setMode(TCB_CNTMODE_PWM8_gc);
timer->CCMPL = period;
timer->CCMPH = compare;
enableOutput();
enable();
}
void getPwmMode(byte & period, byte & compare) {
period = timer->CCMPL;
compare = timer->CCMPH;
}
void setPwm(double frequency, double dutyCycle) {
TCB_CLKSEL_t clockSource = TCB_CLKSEL_CLKDIV1_gc;
double clockFrequency = getFrequencyOfClock(clockSource);
if(frequency < (clockFrequency/256.)) {
clockSource = TCB_CLKSEL_CLKDIV2_gc;
clockFrequency = getFrequencyOfClock(clockSource);
}
if(frequency < (clockFrequency/256.)) {
clockSource = TCB_CLKSEL_CLKTCA_gc;
clockFrequency = getFrequencyOfClock(clockSource);
}
double period = (clockFrequency / frequency) - 1.0 + 0.5;
if(period > 255.) period = 255.;
if(period < 0.) period = 0.0;
double compare = period * dutyCycle + 0.5;
if(compare < 0.0) compare = 0.0;
if(compare > period) compare = period;
setPwmMode((byte)(period),(byte)(compare));
}
void getPwm(double & frequency, double & dutyCycle) {
byte period, compare;
getPwmMode(period,compare);
frequency = getClockFrequency() / (((double)period) + 1);
dutyCycle = (double) compare / (((double)period) + 1);
}
void setTimerMode() {
disable();
disableOutput();
setMode(TCB_CNTMODE_INT_gc);
if(isrCallback != isrDefaultUnused) {
enableInterrupt();
}
}
TCB_t * getTimer() { return timer; }
long getOverflowCounts() { return overflowCounts; }
long getRemainder() { return remainder; }
long getOverflowCounter() { return overflowCounter; }
long getOverflowTime() { return maxTimeWithoutOverflow; }
//protected:
// the next_tick function is called by the interrupt service routine TCB0_INT_vect
//friend extern "C" void TCB0_INT_vect(void);
void next_tick() __attribute__((always_inline)) {
--overflowCounter;
if(overflowCounter > 0) {
return;
}
if(overflowCounter < 0) {
// finished waiting for remainder
if (overflowCounts) {
// restart with a max counter
overflowCounter = overflowCounts;
timer->CCMP = countsPerOverflow;
}
} else {
// overflowCounter == 0
// the overflow series has finished: to the remainder if any
if(remainder) {
timer->CCMP = remainder;
if(timer->CNT < remainder) return;
// remainder is so short: already passed !
timer->CCMP = countsPerOverflow;
}
// no remainder series: reset the overflow counter and do the callback
overflowCounter = overflowCounts;
}
(*isrCallback)();
}
private:
TCB_t * timer = &TCB0;
long overflowCounts = 0;
long remainder = 10;
long overflowCounter = 0;
unsigned long countsPerOverflow = TCB_RESOLUTION - 1;
void (*isrCallback)();
static void isrDefaultUnused();
unsigned long maxTimeWithoutOverflow;
}; // EveryTimerB
extern EveryTimerB TimerB2;
#endif // ARDUINO_ARCH_MEGAAVR
#endif // EveryTimerB_h_

126
MegaAvr20Mhz.h
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@ -1,126 +0,0 @@
#if !defined(MegaAvr20MHz_h_)
#define MegaAvr20MHz_h_
#if defined(ARDUINO_ARCH_MEGAAVR) && (F_CPU == 20000000UL) && defined(MILLIS_USE_TIMERB3)
#define MegaAvr20MHzCorrected
// Quick hack to correct the millis() and micros() functions for 20MHz MegaAVR boards.
// by Kees van der Oord <Kees.van.der.Oord@inter.nl.net>
// Remember to call the function corrected20MHzInit() from setup() or an class constructor !
// in the IDE 1.8.5 the implementation of millis() and micros() is not accurate
// for the MegaAvr achitecture board clocked at 20 MHz:
// 1)
// in ~\Arduino15\packages\arduino\hardware\megaavr\1.8.5\cores\arduino\wiring.c(386)
// microseconds_per_timer_overflow is initialized as:
// microseconds_per_timer_overflow = clockCyclesToMicroseconds(TIME_TRACKING_CYCLES_PER_OVF);
// this evaluates to (256 * 64) / (20000000/1000000)) = 819.2 which is rounded 819.
// the rounding causes millis() and micros() to report times that are 0.2/819.2 = 0.024 % too short
// 2)
// in ~\Arduino15\packages\arduino\hardware\megaavr\1.8.5\cores\arduino\wiring.c(387)
// microseconds_per_timer_tick is defined as:
// microseconds_per_timer_tick = microseconds_per_timer_overflow/TIME_TRACKING_TIMER_PERIOD;
// which evaluates to 819.2 / 255 = 3.21254901960784 which is rounded to 3
// this is wrong in two ways:
// - the TIME_TRACKING_TIMER_PERIOD constant is wrong: this should be TIME_TRACKING_TICKS_PER_OVF
// so the correct value is 3.2 ns/tick
// - the rounding causes micros() to return times that are 0.2/3 = 6.25 % too short
// as a quick hack, initialize these variables with settings a factor 5 larger
// and redefine the millis() and micros() functions to return the corrected values
// The code in this header file corrects for these problems by incrementing the counters
// with increments that are 5 times larger (the lowest factor that gives integer values).
// The millis() and micros() functions are redefined to return the counters / 5.
// The costs you pay is that the number of clock cycles of the new millis() and micros()
// functions is higher. This should be covered by the fact that the chip runs 25% faster
// at 20 MHz than at 16 MHz.
// This header file redefines the millis() and micros() functions. The redefinition
// is only active for source files in which this header file is included. If you link
// to libraries with a .cpp file, you have to manually change the library .cpp file to
// include this header as well. In addition the corrected20MHzInit() method must be called
// from your sketch to re-initialize the variables used by the timer isr function.
// for micros()
// from wiring.c:
extern volatile uint32_t timer_overflow_count;
inline unsigned long corrected_micros() {
static volatile unsigned long microseconds_offset = 0;
unsigned long overflows, microseconds;
uint8_t ticks;
unsigned long offset;
// Save current state and disable interrupts
uint8_t status = SREG;
cli();
// we need to prevent that the double calculation below exceeds MAX_ULONG
// this assumes that micros() is called at least once every 35mins)
while(timer_overflow_count > 500000UL) {
microseconds_offset += 409600000UL; // 500000 * 819.2 ~ almost 7 minutes
timer_overflow_count -= 500000UL;
}
// Get current number of overflows and timer count
overflows = timer_overflow_count;
ticks = TCB3.CNTL;
offset = microseconds_offset;
// If the timer overflow flag is raised, we just missed it,
// increment to account for it, & read new ticks
if(TCB3.INTFLAGS & TCB_CAPT_bm){
overflows++;
ticks = TCB3.CNTL;
}
// Restore state
SREG = status;
// Return microseconds of up time (resets every ~70mins)
// float aritmic is faster than integer multiplication ?
return offset + (unsigned long)((overflows * 819.2) + (ticks * 3.2));
}
#define micros corrected_micros
// for millis()
// from wiring.c:
extern volatile uint32_t timer_millis;
extern uint16_t millis_inc;
extern uint16_t fract_inc;
// call this method from your sketch setup() if you include this file !
inline void corrected20MHzInit(void) {
fract_inc = 96; // (5 * 819.2) % 1000
millis_inc = 4; // (5 * 819.2) / 1000
}
inline unsigned long corrected_millis() {
static volatile unsigned long last = 0;
static volatile unsigned long integer = 0;
static volatile unsigned long fraction = 0;
unsigned long m;
// disable interrupts while we read timer_millis or we might get an
// inconsistent value (e.g. in the middle of a write to timer_millis)
uint8_t status = SREG;
cli();
unsigned long elapsed = timer_millis - last;
last = timer_millis;
integer += elapsed / 5;
fraction += elapsed % 5;
if(fraction >= 5) { ++integer; fraction -= 5; }
m = integer;
SREG = status;
return m;
}
#define millis corrected_millis
#endif // defined(ARDUINO_ARCH_MEGAAVR) && (F_CPU == 20000000UL) && defined(MILLIS_USE_TIMERB3)
#endif // !defined(MegaAvr20MHz_h_)