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Proper AVR preemptive interrupt handling (#10501)

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Co-Authored-By: ejtagle <ejtagle@hotmail.com>
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Scott Lahteine 2018-04-23 20:47:31 -05:00 • committed by GitHub
parent 0764981aa1
commit 51004e003d
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5 changed files with 47 additions and 38 deletions
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36
Marlin/temperature.cpp
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@ -1263,7 +1263,7 @@ void Temperature::init() {
// Use timer0 for temperature measurement
// Interleave temperature interrupt with millies interrupt
OCR0B = 128;
SBI(TIMSK0, OCIE0B);
ENABLE_TEMPERATURE_INTERRUPT();
// Wait for temperature measurement to settle
delay(250);
@ -1778,20 +1778,26 @@ void Temperature::set_current_temp_raw() {
* - For PINS_DEBUGGING, monitor and report endstop pins
* - For ENDSTOP_INTERRUPTS_FEATURE check endstops if flagged
*/
ISR(TIMER0_COMPB_vect) { Temperature::isr(); }
volatile bool Temperature::in_temp_isr = false;
void Temperature::isr() {
// The stepper ISR can interrupt this ISR. When it does it re-enables this ISR
// at the end of its run, potentially causing re-entry. This flag prevents it.
if (in_temp_isr) return;
in_temp_isr = true;
// Allow UART and stepper ISRs
CBI(TIMSK0, OCIE0B); //Disable Temperature ISR
ISR(TIMER0_COMPB_vect) {
/**
* AVR has no hardware interrupt preemption, so emulate priorization
* and preemption of this ISR by all others by disabling the timer
* interrupt generation capability and reenabling global interrupts.
* Any interrupt can then interrupt this handler and preempt it.
* This ISR becomes the lowest priority one so the UART, Endstops
* and Stepper ISRs can all preempt it.
*/
DISABLE_TEMPERATURE_INTERRUPT();
sei();
Temperature::isr();
// Disable global interrupts and reenable this ISR
cli();
ENABLE_TEMPERATURE_INTERRUPT();
}
void Temperature::isr() {
static int8_t temp_count = -1;
static ADCSensorState adc_sensor_state = StartupDelay;
static uint8_t pwm_count = _BV(SOFT_PWM_SCALE);
@ -2328,10 +2334,6 @@ void Temperature::isr() {
e_hit--;
}
#endif
cli();
in_temp_isr = false;
SBI(TIMSK0, OCIE0B); //re-enable Temperature ISR
}
#if HAS_TEMP_SENSOR