diff --git a/Marlin/src/HAL/HAL_ESP32/HAL.h b/Marlin/src/HAL/HAL_ESP32/HAL.h index 2e0cd32ec..2c6858ba9 100644 --- a/Marlin/src/HAL/HAL_ESP32/HAL.h +++ b/Marlin/src/HAL/HAL_ESP32/HAL.h @@ -137,3 +137,44 @@ void HAL_adc_start_conversion(uint8_t adc_pin); void HAL_idletask(); void HAL_init(); void HAL_init_board(); + +// +// Delay in cycles (used by DELAY_NS / DELAY_US) +// +FORCE_INLINE static void DELAY_CYCLES(uint32_t x) { + unsigned long start, ccount, stop; + + /** + * It's important to care for race conditions (and overflows) here. + * Race condition example: If `stop` calculates to being close to the upper boundary of + * `uint32_t` and if at the same time a longer loop interruption kicks in (e.g. due to other + * FreeRTOS tasks or interrupts), `ccount` might overflow (and therefore be below `stop` again) + * without the loop ever being able to notice that `ccount` had already been above `stop` once + * (and that therefore the number of cycles to delay has already passed). + * As DELAY_CYCLES (through DELAY_NS / DELAY_US) is used by software SPI bit banging to drive + * LCDs and therefore might be called very, very often, this seemingly improbable situation did + * actually happen in reality. It resulted in apparently random print pauses of ~17.9 seconds + * (0x100000000 / 240 MHz) or multiples thereof, essentially ruining the current print by causing + * large blobs of filament. + */ + + __asm__ __volatile__ ( "rsr %0, ccount" : "=a" (start) ); + stop = start + x; + ccount = start; + + if (stop >= start) { + // no overflow, so only loop while in between start and stop: + // 0x00000000 -----------------start****stop-- 0xffffffff + while (ccount >= start && ccount < stop) { + __asm__ __volatile__ ( "rsr %0, ccount" : "=a" (ccount) ); + } + } + else { + // stop did overflow, so only loop while outside of stop and start: + // 0x00000000 **stop-------------------start** 0xffffffff + while (ccount >= start || ccount < stop) { + __asm__ __volatile__ ( "rsr %0, ccount" : "=a" (ccount) ); + } + } + +} diff --git a/Marlin/src/HAL/HAL_ESP32/Servo.cpp b/Marlin/src/HAL/HAL_ESP32/Servo.cpp index 3c3b8fa70..c80c29a4e 100644 --- a/Marlin/src/HAL/HAL_ESP32/Servo.cpp +++ b/Marlin/src/HAL/HAL_ESP32/Servo.cpp @@ -37,7 +37,7 @@ Servo::Servo() { int8_t Servo::attach(const int inPin) { if (channel >= CHANNEL_MAX_NUM) return -1; - if (pin > 0) pin = inPin; + if (inPin > 0) pin = inPin; ledcSetup(channel, 50, 16); // channel X, 50 Hz, 16-bit depth ledcAttachPin(pin, channel); diff --git a/Marlin/src/HAL/shared/Delay.h b/Marlin/src/HAL/shared/Delay.h index b1dafbb0f..4ba14d968 100644 --- a/Marlin/src/HAL/shared/Delay.h +++ b/Marlin/src/HAL/shared/Delay.h @@ -145,21 +145,7 @@ } #undef nop -#elif defined(ESP32) - - FORCE_INLINE static void DELAY_CYCLES(uint32_t x) { - unsigned long ccount, stop; - - __asm__ __volatile__ ( "rsr %0, ccount" : "=a" (ccount) ); - - stop = ccount + x; // This can overflow - - while (ccount < stop) { // This doesn't deal with overflows - __asm__ __volatile__ ( "rsr %0, ccount" : "=a" (ccount) ); - } - } - -#elif defined(__PLAT_LINUX__) +#elif defined(__PLAT_LINUX__) || defined(ESP32) // specified inside platform