mirror of https://github.com/arendst/Tasmota.git
Fix PWM flickering at low levels (#7415)
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Hadinger
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ed455df760
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@ -4,6 +4,7 @@
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- Change wifi connectivity stability (#7602)
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- Add ``SetOption84 1`` sends AWS IoT device shadow updates (alternative to retained)
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- Fix PWM flickering at low levels (#7415)
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### 8.1.0.4 20200116
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@ -0,0 +1,317 @@
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/*
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esp8266_waveform - General purpose waveform generation and control,
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supporting outputs on all pins in parallel.
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Copyright (c) 2018 Earle F. Philhower, III. All rights reserved.
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The core idea is to have a programmable waveform generator with a unique
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high and low period (defined in microseconds). TIMER1 is set to 1-shot
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mode and is always loaded with the time until the next edge of any live
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waveforms.
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Up to one waveform generator per pin supported.
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Each waveform generator is synchronized to the ESP cycle counter, not the
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timer. This allows for removing interrupt jitter and delay as the counter
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always increments once per 80MHz clock. Changes to a waveform are
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contiguous and only take effect on the next waveform transition,
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allowing for smooth transitions.
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This replaces older tone(), analogWrite(), and the Servo classes.
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Everywhere in the code where "cycles" is used, it means ESP.getCycleTime()
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cycles, not TIMER1 cycles (which may be 2 CPU clocks @ 160MHz).
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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// Use PWM from core 2.4.0 as all versions below 2.5.0-beta3 produce LED flickering when settings are saved to flash
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#include <core_version.h>
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#if defined(ARDUINO_ESP8266_RELEASE_2_6_1) || defined(ARDUINO_ESP8266_RELEASE_2_6_2) || defined(ARDUINO_ESP8266_RELEASE_2_6_3)
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#warning **** Tasmota is using a patched PWM Arduino version as planned ****
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#include <Arduino.h>
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#include "ets_sys.h"
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#include "core_esp8266_waveform.h"
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extern "C" {
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// Maximum delay between IRQs
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#define MAXIRQUS (10000)
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// Set/clear GPIO 0-15 by bitmask
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#define SetGPIO(a) do { GPOS = a; } while (0)
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#define ClearGPIO(a) do { GPOC = a; } while (0)
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// Waveform generator can create tones, PWM, and servos
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typedef struct {
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uint32_t nextServiceCycle; // ESP cycle timer when a transition required
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uint32_t expiryCycle; // For time-limited waveform, the cycle when this waveform must stop
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uint32_t nextTimeHighCycles; // Copy over low->high to keep smooth waveform
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uint32_t nextTimeLowCycles; // Copy over high->low to keep smooth waveform
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} Waveform;
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static Waveform waveform[17]; // State of all possible pins
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static volatile uint32_t waveformState = 0; // Is the pin high or low, updated in NMI so no access outside the NMI code
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static volatile uint32_t waveformEnabled = 0; // Is it actively running, updated in NMI so no access outside the NMI code
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// Enable lock-free by only allowing updates to waveformState and waveformEnabled from IRQ service routine
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static volatile uint32_t waveformToEnable = 0; // Message to the NMI handler to start a waveform on a inactive pin
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static volatile uint32_t waveformToDisable = 0; // Message to the NMI handler to disable a pin from waveform generation
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static uint32_t (*timer1CB)() = NULL;
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// Non-speed critical bits
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#pragma GCC optimize ("Os")
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static inline ICACHE_RAM_ATTR uint32_t GetCycleCount() {
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uint32_t ccount;
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__asm__ __volatile__("esync; rsr %0,ccount":"=a"(ccount));
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return ccount;
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}
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// Interrupt on/off control
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static ICACHE_RAM_ATTR void timer1Interrupt();
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static bool timerRunning = false;
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static void initTimer() {
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timer1_disable();
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ETS_FRC_TIMER1_INTR_ATTACH(NULL, NULL);
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ETS_FRC_TIMER1_NMI_INTR_ATTACH(timer1Interrupt);
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timer1_enable(TIM_DIV1, TIM_EDGE, TIM_SINGLE);
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timerRunning = true;
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}
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static void ICACHE_RAM_ATTR deinitTimer() {
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ETS_FRC_TIMER1_NMI_INTR_ATTACH(NULL);
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timer1_disable();
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timer1_isr_init();
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timerRunning = false;
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}
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// Set a callback. Pass in NULL to stop it
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void setTimer1Callback(uint32_t (*fn)()) {
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timer1CB = fn;
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if (!timerRunning && fn) {
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initTimer();
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timer1_write(microsecondsToClockCycles(1)); // Cause an interrupt post-haste
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} else if (timerRunning && !fn && !waveformEnabled) {
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deinitTimer();
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}
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}
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// Start up a waveform on a pin, or change the current one. Will change to the new
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// waveform smoothly on next low->high transition. For immediate change, stopWaveform()
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// first, then it will immediately begin.
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int startWaveform(uint8_t pin, uint32_t timeHighUS, uint32_t timeLowUS, uint32_t runTimeUS) {
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if ((pin > 16) || isFlashInterfacePin(pin)) {
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return false;
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}
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Waveform *wave = &waveform[pin];
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// Adjust to shave off some of the IRQ time, approximately
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wave->nextTimeHighCycles = microsecondsToClockCycles(timeHighUS);
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wave->nextTimeLowCycles = microsecondsToClockCycles(timeLowUS);
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wave->expiryCycle = runTimeUS ? GetCycleCount() + microsecondsToClockCycles(runTimeUS) : 0;
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if (runTimeUS && !wave->expiryCycle) {
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wave->expiryCycle = 1; // expiryCycle==0 means no timeout, so avoid setting it
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}
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uint32_t mask = 1<<pin;
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if (!(waveformEnabled & mask)) {
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// Actually set the pin high or low in the IRQ service to guarantee times
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wave->nextServiceCycle = GetCycleCount() + microsecondsToClockCycles(1);
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waveformToEnable |= mask;
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if (!timerRunning) {
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initTimer();
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timer1_write(microsecondsToClockCycles(10));
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} else {
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// Ensure timely service....
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if (T1L > microsecondsToClockCycles(10)) {
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timer1_write(microsecondsToClockCycles(10));
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}
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}
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while (waveformToEnable) {
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delay(0); // Wait for waveform to update
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}
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}
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return true;
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}
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// Speed critical bits
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#pragma GCC optimize ("O2")
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// Normally would not want two copies like this, but due to different
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// optimization levels the inline attribute gets lost if we try the
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// other version.
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static inline ICACHE_RAM_ATTR uint32_t GetCycleCountIRQ() {
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uint32_t ccount;
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__asm__ __volatile__("rsr %0,ccount":"=a"(ccount));
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return ccount;
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}
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static inline ICACHE_RAM_ATTR uint32_t min_u32(uint32_t a, uint32_t b) {
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if (a < b) {
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return a;
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}
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return b;
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}
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// Stops a waveform on a pin
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int ICACHE_RAM_ATTR stopWaveform(uint8_t pin) {
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// Can't possibly need to stop anything if there is no timer active
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if (!timerRunning) {
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return false;
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}
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// If user sends in a pin >16 but <32, this will always point to a 0 bit
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// If they send >=32, then the shift will result in 0 and it will also return false
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uint32_t mask = 1<<pin;
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if (!(waveformEnabled & mask)) {
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return false; // It's not running, nothing to do here
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}
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waveformToDisable |= mask;
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// Ensure timely service....
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if (T1L > microsecondsToClockCycles(10)) {
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timer1_write(microsecondsToClockCycles(10));
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}
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while (waveformToDisable) {
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/* no-op */ // Can't delay() since stopWaveform may be called from an IRQ
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}
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if (!waveformEnabled && !timer1CB) {
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deinitTimer();
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}
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return true;
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}
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// The SDK and hardware take some time to actually get to our NMI code, so
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// decrement the next IRQ's timer value by a bit so we can actually catch the
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// real CPU cycle counter we want for the waveforms.
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#if F_CPU == 80000000
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#define DELTAIRQ (microsecondsToClockCycles(3))
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#else
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#define DELTAIRQ (microsecondsToClockCycles(2))
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#endif
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static ICACHE_RAM_ATTR void timer1Interrupt() {
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// Optimize the NMI inner loop by keeping track of the min and max GPIO that we
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// are generating. In the common case (1 PWM) these may be the same pin and
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// we can avoid looking at the other pins.
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static int startPin = 0;
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static int endPin = 0;
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uint32_t nextEventCycles = microsecondsToClockCycles(MAXIRQUS);
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uint32_t timeoutCycle = GetCycleCountIRQ() + microsecondsToClockCycles(14);
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if (waveformToEnable || waveformToDisable) {
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// Handle enable/disable requests from main app.
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waveformEnabled = (waveformEnabled & ~waveformToDisable) | waveformToEnable; // Set the requested waveforms on/off
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waveformState &= ~waveformToEnable; // And clear the state of any just started
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waveformToEnable = 0;
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waveformToDisable = 0;
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// Find the first GPIO being generated by checking GCC's find-first-set (returns 1 + the bit of the first 1 in an int32_t)
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startPin = __builtin_ffs(waveformEnabled) - 1;
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// Find the last bit by subtracting off GCC's count-leading-zeros (no offset in this one)
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endPin = 32 - __builtin_clz(waveformEnabled);
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}
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bool done = false;
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if (waveformEnabled) {
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do {
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nextEventCycles = microsecondsToClockCycles(MAXIRQUS);
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for (int i = startPin; i <= endPin; i++) {
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uint32_t mask = 1<<i;
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// If it's not on, ignore!
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if (!(waveformEnabled & mask)) {
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continue;
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}
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Waveform *wave = &waveform[i];
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uint32_t now = GetCycleCountIRQ();
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// Disable any waveforms that are done
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if (wave->expiryCycle) {
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int32_t expiryToGo = wave->expiryCycle - now;
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if (expiryToGo < 0) {
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// Done, remove!
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waveformEnabled &= ~mask;
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if (i == 16) {
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GP16O &= ~1;
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} else {
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ClearGPIO(mask);
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}
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continue;
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}
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}
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// Check for toggles
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int32_t cyclesToGo = wave->nextServiceCycle - now;
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if (cyclesToGo < 0) {
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waveformState ^= mask;
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if (waveformState & mask) {
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if (i == 16) {
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GP16O |= 1; // GPIO16 write slow as it's RMW
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} else {
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SetGPIO(mask);
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}
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wave->nextServiceCycle = now + wave->nextTimeHighCycles + cyclesToGo;
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nextEventCycles = min_u32(nextEventCycles, min_u32(wave->nextTimeHighCycles + cyclesToGo, 1));
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} else {
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if (i == 16) {
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GP16O &= ~1; // GPIO16 write slow as it's RMW
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} else {
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ClearGPIO(mask);
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}
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wave->nextServiceCycle = now + wave->nextTimeLowCycles + cyclesToGo;
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nextEventCycles = min_u32(nextEventCycles, min_u32(wave->nextTimeLowCycles + cyclesToGo, 1));
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}
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} else {
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uint32_t deltaCycles = wave->nextServiceCycle - now;
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nextEventCycles = min_u32(nextEventCycles, deltaCycles);
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}
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}
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// Exit the loop if we've hit the fixed runtime limit or the next event is known to be after that timeout would occur
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uint32_t now = GetCycleCountIRQ();
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int32_t cycleDeltaNextEvent = timeoutCycle - (now + nextEventCycles);
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int32_t cyclesLeftTimeout = timeoutCycle - now;
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done = (cycleDeltaNextEvent < 0) || (cyclesLeftTimeout < 0);
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} while (!done);
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} // if (waveformEnabled)
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if (timer1CB) {
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nextEventCycles = min_u32(nextEventCycles, timer1CB());
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}
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if (nextEventCycles < microsecondsToClockCycles(10)) {
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nextEventCycles = microsecondsToClockCycles(10);
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}
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nextEventCycles -= DELTAIRQ;
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// Do it here instead of global function to save time and because we know it's edge-IRQ
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#if F_CPU == 160000000
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T1L = nextEventCycles >> 1; // Already know we're in range by MAXIRQUS
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#else
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T1L = nextEventCycles; // Already know we're in range by MAXIRQUS
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#endif
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TEIE |= TEIE1; // Edge int enable
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}
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};
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#endif // ARDUINO_ESP8266_RELEASE
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