mirror of
https://github.com/DCC-EX/CommandStation-EX.git
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391 lines
14 KiB
C++
391 lines
14 KiB
C++
// EveryTimerB library.
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// by Kees van der Oord Kees.van.der.Oord@inter.nl.net
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// Timer library for the TCB timer of the AtMega4809 processor.
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// tested on the Arduino Nano Every (AtMega4809) and the Arduino 1.8.12 IDE
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// support for the Every is the 'Arduino MegaAVR' boards module (Tools | Board | Boards Manager)
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// usage:
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/*
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#ifdef ARDUINO_ARCH_MEGAAVR
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#include "EveryTimerB.h"
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#define Timer1 TimerB2 // use TimerB2 as a drop in replacement for Timer1
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#else // assume architecture supported by TimerOne library ....
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#include "TimerOne.h"
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#endif
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// code below will now work both on the MegaAVR and AVR processors
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void setup() {
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Timer1.initialize();
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Timer1.attachInterrupt(myisr);
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Timer1.setPeriod(1000000UL); // like the TimerOne library this will start the timer as well
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}
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void myisr() {
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// do something useful every second
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}
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*/
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// clock source options:
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// The TCB clock source is specified in the initialize() function with default value EveryTimerB_CLOCMODE.
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// define this macro before including this file to use a different default clock mode
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// e.g.:
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// #define EveryTimerB_CLOCMODE TCB_CLKSEL_CLKTCA_gc // 250 kHz ~ 4 us
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// #define EveryTimerB_CLOCMODE TCB_CLKSEL_CLKDIV2_gc // 8 MHz ~ 0.125 us
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// #define EveryTimerB_CLOCMODE TCB_CLKSEL_CLKDIV_gc // 16 MHz ~ 0.0625 us
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// timer options
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// The 4809 has one A timer (TCA) and four B timers (TCB).
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// TCA and TCB3 are used by the arduino core to generate the clock used by millis() and micros().
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// TCB0 generates the PWM timing for pin D6, TCB1 for pin D3.
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// By default Timer Control B2 is defined as TimerB2 in the EveryTimerB library.
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// If you would like to use the TCB0 and TCB1 as well you have to copy the code
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// from the EveryTimerB.cpp into your product file and adapt for B0 and B1 timers.
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//
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// for information on the 4809 TCA and TCB timers:
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// http://ww1.microchip.com/downloads/en/AppNotes/TB3217-Getting-Started-with-TCA-90003217A.pdf
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// http://ww1.microchip.com/downloads/en/Appnotes/TB3214-Getting-Started-with-TCB-90003214A.pdf
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// %LOCALAPPDATA%\Arduino15\packages\arduino\hardware\megaavr\1.8.5\cores\arduino\wiring.c
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// %LOCALAPPDATA%\Arduino15\packages\arduino\hardware\megaavr\1.8.5\variants\nona4809\variant.c
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// %LOCALAPPDATA%\Arduino15\packages\arduino\tools\avr-gcc\7.3.0-atmel3.6.1-arduino5\avr\include\avr\iom4809.h
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// 20 MHz system clock
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// to run the Every at 20 MHz, add the lines below to the nona4809 section of the boards.txt file
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// in %LOCALAPPDATA%\Arduino15\packages\arduino\hardware\megaavr\1.8.5.
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// they add the sub menu 'Tools | Clock' to choose between 16MHz and 20MHz.
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/*
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menu.clock=Clock
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nona4809.menu.clock.16internal=16MHz
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nona4809.menu.clock.16internal.build.f_cpu=16000000L
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nona4809.menu.clock.16internal.bootloader.OSCCFG=0x01
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nona4809.menu.clock.20internal=20MHz
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nona4809.menu.clock.20internal.build.f_cpu=20000000L
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nona4809.menu.clock.20internal.bootloader.OSCCFG=0x02
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*/
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// On 20Mhz, the 1.8.12 IDE MegaAvr core library implementation
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// of the millis() and micros() functions is not accurate.
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// the file "MegaAvr20MHz.h" implements a quick hack to correct for this
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//
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// to do:
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// there is no range check on the 'period' arguments of setPeriod ...
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// check if it is necessary to set the CNT register to 0 in start()
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#ifndef EveryTimerB_h_
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#define EveryTimerB_h_
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#ifdef ARDUINO_ARCH_MEGAAVR
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#ifndef EveryTimerB_CLOCMODE
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#define EveryTimerB_CLOCMODE TCB_CLKSEL_CLKTCA_gc
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#endif
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#if defined(ARDUINO) && ARDUINO >= 100
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#include "Arduino.h"
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#else
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#include "WProgram.h"
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#endif
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#include "MegaAvr20Mhz.h"
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#include "pins_arduino.h"
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#define TCB_RESOLUTION 65536UL // TCB is 16 bit
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// CLOCK F_CPU DIV TICK OVERFLOW OVERFLOW/s
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// CLKTCA 16MHz 64 4000 ns 262144us 3.8 Hz
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// CLKDIV2 16MHz 2 125 ns 8192us 122 Hz
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// CLKDIV1 16MHz 1 62.5ns 4096us 244 Hz
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// CLKTCA 20MHz 64 3200 ns 209716us 4.8 Hz
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// CLKDIV2 20MHz 2 100 ns 6554us 153 Hz
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// CLKDIV1 20MHz 1 50 ns 3277us 305 Hz
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class EveryTimerB
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{
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public:
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// The AtMega Timer Control B clock sources selection:
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// TCB_CLKSEL_CLKTCA_gc, // Timer Controller A, Arduino framework sets TCA to F_CPU/64 = 250kHz (4us) @ 16MHz or 312.5kHz (3.2us) @ 20MHz
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// TCB_CLKSEL_CLKDIV2_gc, // CLK_PER/2 Peripheral Clock / 2: 8MHz @ 16Mhz or 10MHz @ 20MHz
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// TCB_CLKSEL_CLKDIV1_gc // CLK_PER Peripheral Clock: 16MHz @ 16Mhz or 20MHz @ 20MHz
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// intialize: sets the timer compare mode and the clock source
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void initialize(TCB_t * timer_ = &TCB2, TCB_CLKSEL_t clockSource = EveryTimerB_CLOCMODE, unsigned long period = 1000000UL) __attribute__((always_inline)) {
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timer = timer_;
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#if defined(MegaAvr20MHzCorrected)
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corrected20MHzInit(); // see commment in MegaAvr20MHz_h
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#endif
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stop();
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timer->CTRLB = TCB_CNTMODE_INT_gc & ~TCB_CCMPEN_bm; // timer compare mode with output disabled
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if(clockSource) setClockSource(clockSource);
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if(period) setPeriod(period);
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}
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void setClockSource(TCB_CLKSEL_t clockSource) __attribute__((always_inline)) {
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timer->CTRLA = clockSource; // this stops the clock as well ...
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switch(clockSource) {
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#if F_CPU == 20000000UL
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case TCB_CLKSEL_CLKTCA_gc: maxTimeWithoutOverflow = 209715; break; // (TCB_RESOLUTION * 64) / 20
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case TCB_CLKSEL_CLKDIV2_gc: maxTimeWithoutOverflow = 6553; break; // (TCB_RESOLUTION * 2) / 20
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case TCB_CLKSEL_CLKDIV1_gc: maxTimeWithoutOverflow = 3276; break; // (TCB_RESOLUTION * 1) / 20
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#else
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case TCB_CLKSEL_CLKTCA_gc: maxTimeWithoutOverflow = 262144; break;
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case TCB_CLKSEL_CLKDIV2_gc: maxTimeWithoutOverflow = 8192; break;
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case TCB_CLKSEL_CLKDIV1_gc: maxTimeWithoutOverflow = 4096; break;
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#endif
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}
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}
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TCB_CLKSEL_t getClockSource() {
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return (TCB_CLKSEL_t)(timer->CTRLA & (TCB_CLKSEL_CLKTCA_gc|TCB_CLKSEL_CLKDIV2_gc|TCB_CLKSEL_CLKDIV1_gc));
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}
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double getFrequencyOfClock(TCB_CLKSEL_t clock) {
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switch(clock) {
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// suppose nobody touched the default TCA configuration ...
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case TCB_CLKSEL_CLKTCA_gc: return double(F_CPU/64); break;
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case TCB_CLKSEL_CLKDIV2_gc: return double(F_CPU/2); break;
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case TCB_CLKSEL_CLKDIV1_gc: return double(F_CPU); break;
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}
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return 0.0;
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}
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double getClockFrequency() {
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return getFrequencyOfClock(getClockSource());
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}
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// setPeriod: sets the period
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// note: max and min values are different for each clock
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// CLKTCA: conversion from us to ticks multiplies 'period' first with 10, so max value is MAX_ULONG/10 ~ 1 hr 11 minutes 34 seconds
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// CLKDIV2: conversion from us to ticks is a *10 multiplication, so max value is 420M us (~ 7 minutes)
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// CLKDIV1: conversion from us to ticks is a *20 multiplication, so max value is 210M us (~ 3.5 minutes)
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void setPeriod(unsigned long period /* us */) __attribute__((always_inline)) {
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timer->CTRLA &= ~TCB_ENABLE_bm;
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// conversion from us to ticks depends on the clock
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switch(timer->CTRLA & TCB_CLKSEL_gm)
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{
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case TCB_CLKSEL_CLKTCA_gc:
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#if F_CPU == 20000000UL
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period = (period * 10) / 32; // 20Mhz / 64x clock divider of TCA => 3.2 us / tick
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#else // 16000000UL
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period /= 4; // 16MHz / 64x clock divider of TCA => 4 us / tock
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#endif
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break;
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case TCB_CLKSEL_CLKDIV2_gc:
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#if F_CPU == 20000000UL
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period *= 10; // 20MHz / 2x clock divider => 10 ticks / us
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#else // 16000000UL
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period *= 8; // 16MHz / 2x clock divider => 8 ticks / us
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#endif
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break;
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case TCB_CLKSEL_CLKDIV1_gc:
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#if F_CPU == 20000000UL
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period *= 20; // 20MHz: 20 ticks / us
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#else // 16000000UL
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period *= 16; // 16MHz: 16 ticks / u3
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#endif
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break;
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}
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// to support longer than TCB_RESOLUTION ticks,
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// this class supports first waiting for N 'overflowCounts'
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// and next program the timer the remaining 'remainder' ticks:
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countsPerOverflow = TCB_RESOLUTION;
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overflowCounts = period / TCB_RESOLUTION;
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remainder = period % TCB_RESOLUTION;
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// the timer period is always one tick longer than programmed,
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// so a remainder of 1 is not possible. reduce the length of
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// the 'overflow' cycles to get a remainder that is not 1
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if(overflowCounts) {
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while(remainder == 1) {
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--countsPerOverflow;
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overflowCounts = period / countsPerOverflow;
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remainder = period % countsPerOverflow;
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}
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}
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// the timer period is always one tick longer than programmed
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--countsPerOverflow;
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if(remainder) --remainder;
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// let's go
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start();
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}
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void start() __attribute__((always_inline)) {
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stop();
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overflowCounter = overflowCounts;
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timer->CCMP = overflowCounts ? countsPerOverflow : remainder;
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timer->CNT = 0;
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timer->CTRLA |= TCB_ENABLE_bm;
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}
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void stop() __attribute__((always_inline)) {
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timer->CTRLA &= ~TCB_ENABLE_bm;
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timer->INTFLAGS = TCB_CAPT_bm; // writing to the INTFLAGS register will clear the interrupt request flag
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}
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bool isEnabled(void) __attribute__((always_inline)) {
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return timer->CTRLA & TCB_ENABLE_bm ? true : false;
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}
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void enable(void) __attribute__((always_inline)) {
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timer->CTRLA |= TCB_ENABLE_bm;
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}
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void disable(void) __attribute__((always_inline)) {
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timer->CTRLA &= ~TCB_ENABLE_bm;
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}
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void attachInterrupt(void (*isr)()) __attribute__((always_inline)) {
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isrCallback = isr;
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timer->INTFLAGS = TCB_CAPT_bm; // clear interrupt request flag
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timer->INTCTRL = TCB_CAPT_bm; // Enable the interrupt
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}
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void attachInterrupt(void (*isr)(), unsigned long microseconds) __attribute__((always_inline)) {
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if(microseconds > 0) stop();
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attachInterrupt(isr);
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if (microseconds > 0) setPeriod(microseconds);
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}
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void detachInterrupt() __attribute__((always_inline)) {
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timer->INTCTRL &= ~TCB_CAPT_bm; // Disable the interrupt
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isrCallback = isrDefaultUnused;
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}
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void enableInterrupt() __attribute__((always_inline)) {
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timer->INTFLAGS = TCB_CAPT_bm; // clear interrupt request flag
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timer->INTCTRL = TCB_CAPT_bm; // Enable the interrupt
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}
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void disableInterrupt() __attribute__((always_inline)) {
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timer->INTCTRL &= ~TCB_CAPT_bm; // Enable the interrupt
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}
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TCB_CNTMODE_enum getMode() __attribute__((always_inline)) {
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return (TCB_CNTMODE_enum) (timer->CTRLB & 0x7);
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}
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void setMode(TCB_CNTMODE_enum mode) __attribute__((always_inline)) {
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timer->CTRLB = (timer->CTRLB & ~0x7) | mode;
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}
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uint8_t isOutputEnabled() __attribute__((always_inline)) {
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return timer->CTRLB & TCB_CCMPEN_bm;
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}
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void enableOutput() __attribute__((always_inline)) {
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timer->CTRLB |= TCB_CCMPEN_bm;
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}
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void disableOutput() __attribute__((always_inline)) {
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timer->CTRLB &= ~TCB_CCMPEN_bm;
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}
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// this will start PWM on pin 6 (TCB0) or pin 3 (TCB1)
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// set the pins to output with setMode(x,OUTPUT) before calling this function
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// period determines the clock ticks in one cycle:
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// 16MHz clock: slowest frequency at 255 = 62 kHz.
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// 8MHz clock: slowest frequency at 255 = 31 kHz.
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// 256kHz clock: slowest frequency at 255 = 1 kHz.
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// compare determines the duty cycle.
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// with a period of 255, set the compare to 128 to get 50% duty cycle.
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void setPwmMode(byte period, byte compare) {
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disableInterrupt();
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setMode(TCB_CNTMODE_PWM8_gc);
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timer->CCMPL = period;
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timer->CCMPH = compare;
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enableOutput();
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enable();
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}
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void getPwmMode(byte & period, byte & compare) {
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period = timer->CCMPL;
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compare = timer->CCMPH;
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}
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void setPwm(double frequency, double dutyCycle) {
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TCB_CLKSEL_t clockSource = TCB_CLKSEL_CLKDIV1_gc;
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double clockFrequency = getFrequencyOfClock(clockSource);
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if(frequency < (clockFrequency/256.)) {
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clockSource = TCB_CLKSEL_CLKDIV2_gc;
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clockFrequency = getFrequencyOfClock(clockSource);
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}
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if(frequency < (clockFrequency/256.)) {
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clockSource = TCB_CLKSEL_CLKTCA_gc;
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clockFrequency = getFrequencyOfClock(clockSource);
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}
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double period = (clockFrequency / frequency) - 1.0 + 0.5;
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if(period > 255.) period = 255.;
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if(period < 0.) period = 0.0;
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double compare = period * dutyCycle + 0.5;
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if(compare < 0.0) compare = 0.0;
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if(compare > period) compare = period;
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setPwmMode((byte)(period),(byte)(compare));
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}
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void getPwm(double & frequency, double & dutyCycle) {
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byte period, compare;
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getPwmMode(period,compare);
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frequency = getClockFrequency() / (((double)period) + 1);
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dutyCycle = (double) compare / (((double)period) + 1);
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}
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void setTimerMode() {
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disable();
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disableOutput();
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setMode(TCB_CNTMODE_INT_gc);
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if(isrCallback != isrDefaultUnused) {
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enableInterrupt();
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}
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}
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TCB_t * getTimer() { return timer; }
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long getOverflowCounts() { return overflowCounts; }
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long getRemainder() { return remainder; }
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long getOverflowCounter() { return overflowCounter; }
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long getOverflowTime() { return maxTimeWithoutOverflow; }
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//protected:
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// the next_tick function is called by the interrupt service routine TCB0_INT_vect
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//friend extern "C" void TCB0_INT_vect(void);
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void next_tick() __attribute__((always_inline)) {
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--overflowCounter;
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if(overflowCounter > 0) {
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return;
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}
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if(overflowCounter < 0) {
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// finished waiting for remainder
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if (overflowCounts) {
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// restart with a max counter
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overflowCounter = overflowCounts;
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timer->CCMP = countsPerOverflow;
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}
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} else {
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// overflowCounter == 0
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// the overflow series has finished: to the remainder if any
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if(remainder) {
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timer->CCMP = remainder;
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if(timer->CNT < remainder) return;
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// remainder is so short: already passed !
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timer->CCMP = countsPerOverflow;
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}
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// no remainder series: reset the overflow counter and do the callback
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overflowCounter = overflowCounts;
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}
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(*isrCallback)();
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}
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private:
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TCB_t * timer = &TCB0;
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long overflowCounts = 0;
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long remainder = 10;
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long overflowCounter = 0;
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unsigned long countsPerOverflow = TCB_RESOLUTION - 1;
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void (*isrCallback)();
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static void isrDefaultUnused();
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unsigned long maxTimeWithoutOverflow;
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}; // EveryTimerB
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extern EveryTimerB TimerB2;
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#endif // ARDUINO_ARCH_MEGAAVR
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#endif // EveryTimerB_h_
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