I seem to remember recent ESP-IDF versions have some allowances to also run C high-level interrupts, but I don't have the details on that. Apparently the expected interrupt latency is around 2 us; alternatively you can write your own high level interrupt handlers in assembler. Board index English Forum Discussion Forum ESP32 Arduino; How to improve interrupt latency with Arduino/C. My code is bellow. A number of small ESP32S2 fixes. The following lines connect the. I suspect the latency comes from the SDK, in the management of interrupt handlers. I have one task at each core. Because there are more interrupt sources than interrupts, sometimes it makes sense to share an interrupt in multiple drivers. Improving Overall Speed. These ESP32-C3 Hardware Timers, using Interrupt, still work even if other functions are blocking. Now I have found the time to do it for myself and with the ESP32 and some other platforms. Espressif IoT Development Framework. @nealmartini The ESP32 is a multiprocessor using a Multitasking operating system (FreeRTOS). Supply 3. Hi, I'm using a GPIO pin as a external interrupt, responding to negedge events. The syntax looks like below. Transmitter code. and at T=9. The ESP32-C3 has one core, with 31 interrupts. This protocol lets numerous ESP boards communicate with each other over a large distance under a sole WLAN. This method will utilise the ESP32 memory directly inside a high-level interrupt. At 17uS, the esp32 responds to the event and sets an IO line to respond, which is too late. sei(): Set interrupt global enable flag bit (re-enable interrupts after being disabled). Now I have found the time to do it for myself and with the ESP32 and some other platforms. Moreover, they are much more precise (certainly depending on clock frequency accuracy) than other software timers using millis() or micros(). Through IO MUX, RTC IO MUX and the GPIO matrix, peripheral input signals can be from any IO pins, and peripheral output signals can be routed to any. So event if running bare metal is mostly of no use for those interface it still got to work. ESP32 module has a dual-core processor and each core consists of 32 interrupts. I think there has been a little bit of progress, although not specifically for this purpose: the GPIO drivers have been optimized a bit so if you use the ESP-IDF API, your interrupt latency should be a bit lower (but not as low as using the bare metal), and ESP-IDF now allows you to have high-prio assembly. The ESP32 SPI slave peripherals are designed as general purpose Devices controlled by a CPU. I have done a measurement and delay from external trigger to application-provided ISR handler is around 2us (at 240MHz clock), which is around 500 cycles. 04 in a VirtualBox. Creating and starting a timer, and dispatching the callback takes some time. I think there has been a little bit of progress, although not specifically for this purpose: the GPIO drivers have been optimized a bit so if you use the ESP-IDF API, your interrupt latency should be a bit lower (but not as low as using the bare metal), and ESP-IDF now allows you to have high-prio assembly interrupt handlers without having to. RF operations of the ESP32 SoC require time-sensitive and interrupt-based software which can be complex. Learn how to use ESP32 PWM with Arduino IDE: ESP32 PWM with Arduino IDE. The ESP32-S2 chip features 43 physical GPIO pins (GPIO0 ~ GPIO21 and GPIO26 ~ GPIO46). The two ESP32 timer groups, with two timer(s) in each, provide the total of four individual timers for use. The ESP32 has eight 16-Bit pulse count units, either for quadrature or single input decoders for reading quadrature encoded signals. I can not figure out how to remove buffer or increase size to as close as possible real time transmission. esp32: PRO CPU has been reset by WDT. 35uS, the master brings the line high. The 1 PPS signal is connected to a second timer (T2) that simply "captures" its value in a register and also triggers an interrupt, at which time we also take a snapshot of T1's value. If a pin was configured as Active Low, physical level low will. This is the reason critical sections should be kept as short as possible. If the ISR for interrupt 0 is executing and interrupt 1 occurs, it will be held until interrupts are turned on again after I0 has finished. Core 0 is known as the “Protocol Core” or “PRO CPU. This is double the 40 MHz default value and doubles the speed at which code is loaded or executed from flash. 04 in a VirtualBox. ; ESP32: The ESP32. greetings sdk: IDF V4. It also takes 26uS to process the IRQ body, though I am using QueueSendfromISR in the. Post by bmakovecki ». 1 Xtensa® Dual-Core 32bit LX7 Microprocessor The microprocessor for the ESP32-S3 SoC inside the NORA-W106 module is a dual-core 32. 2 posts. An OS typically provides multitasking, synchronization, Interrupt and Event Handling, Input/ Output, Inter. Top. At some time later (the latency) you then detect the new message in the queue. Lately, I've been working on a project that consists of programming a Z80 with 8 address and data lines, the clock is done with ledc, it has two external interrupts on the Z80's WR and RD pins --> ESP32. (186) boot. This is double the 40 MHz default value and will double the speed at which code is loaded or executed from flash. A small program that toggles an IO pin. If you can live with 2µs latency, move reaction code into the interrupt (got ~2µs this way, not always feasible, BTW). That needs 2 µs latency to start the waiting task RTOS_2 in core 0. Top. But when the interrupt latency is longer than the narrowest pulse from ledc the edge polarity detection fails and the output-pair is wrong. Post by jfmateos » Mon Nov 07, 2016 9:03 am . Hi, I'm using a GPIO pin as a external interrupt, responding to negedge events. The code is functional, but I can't work with. Only in the case where an RTOS task notification is used in place of a. Board index English Forum Discussion Forum ESP-IDF; Reduce external interrupt latency. But if they are happening simultaneously, then the one with the higher priority runs first and the lower priority gets queued. It needs to save the current CPU registers, program counter. Post by ESP_igrr » Mon Nov 07, 2016 11:36 am . According to the fe310-g002 manual, the interrupt latency of the core is 4 cycles from receiving the interrupt and including the fetch of the first instruction of the handler. If assigning the interrupt in a task. I think there has been a little bit of progress, although not specifically for this purpose: the GPIO drivers have been optimized a bit so if you use the ESP-IDF API, your interrupt latency should be a bit lower (but not as low as using the bare metal), and ESP-IDF now allows you to have high-prio assembly. As opposed to dedicated slaves, CPU-based SPI Devices have a limited number of pre-defined registers. The ESP32-C6 combines 2. : on interrupt load a value from a memory and feed it out a GPIO port) written in assembly. It also takes 26uS to process the IRQ body, though I am using QueueSendfromISR in the. Each interrupt has a fixed priority, most (but not all) interrupts are connected to the interrupt matrix. and it should be PubSubClient client (net); 1 Like. txt" below you can see some details. Interrupt latency on the ESP32 is in the order of microseconds, unfortunately; there's a fair amount of prologue going on. Post by ESP_igrr » Mon Nov 07, 2016 11:36 am . Top. Hi guys, I am implementing an interrupt handler for reception of data through the UART of the ESP32. Arduino Interrupts Latency & Response Time. I use an ADPS-9960 for gesture control which triggers an external interrupt. Because there are more interrupt sources than interrupts, sometimes it makes sense to share an interrupt in multiple drivers. INTENABLE & INTERRUPT gives the bitmask set of currently asserted and enabled interrupts. The code is functional, but I can't work with. Setting a bit and polling this bit in another task within an infinite loop is faster (2 us), but cannot be a real option, because this is waste of resources and prevents from deep sleep options. Alternatively, it may be enough to run the gpio_install_isr_service call on a task that is pinned to CPU1. In particular, for ESP32-WROVER module, call rtc_gpio_isolate (GPIO_NUM_12) before entering deep sleep, to reduce deep sleep current. and at T=9. esp32 GPIO interrupt latency. Re: Interrupt low Latency - again. print ("Current CPU core "); Serial. I only have 1 interrupt setup to trigger on any edge and I am seeing anywhere from 2us to. First of all, the timer should be initialized by calling the function timer_init() and passing a structure. " The ESP32-C3 has one core, with 31 interrupts. jeromeh Posts: 31 Joined: Thu Dec 22, 2016 5:41 am. Interrupt low Latency - again. Post by go4retro » Thu Jan 10, 2019 6:26 am . Ive measured the response by sending the same data I recieve through the TX output of the UART. Serial. bmakovecki Posts: 4 Joined: Fri Nov 03, 2017 9:20 pm. GPIO Interrupt Latency - once more. 1. The 1 PPS signal is connected to a second timer (T2) that simply "captures" its value in a register and also triggers an interrupt, at which time we also take a snapshot of T1's value. Is there a way (if possible code please) to improve it with some. #define configUSE_TIMERS 1. 2 posts • Page 1 of 1. ESP_igrr Posts: 2066 Joined: Tue Dec 01, 2015 8:37 am. bmakovecki Posts: 4 Joined: Fri Nov 03, 2017 9:20 pm. An ESP32 timer group should be identified using timer_group_t. 2 posts • Page 1. 75xVDD. Through oscillometer I found the interval between the pulse and spi cs signal was as much as 100~200 us, while this thread says the interrupt latency can be reduced to about 2 us. The software example below will simply show the count of times it has fired, in the Serial Monitor, and is configured to fire once per second. Depending on the project at hand I switch between two development environments: either ESP-IDF, running under Eclipse on Ubuntu 18. Espressif ESP32 Official Forum. In this tutorial, we will learn to use ESP-MESH network using the painlessMesh library and ESP32/ESP8266 NodeMCU. If using interrupts with multiple modules, since they are open drain they can be tied together if a single interrupt back to the MCU is desired. cases. Interrupt latency on the ESP32 is in the order of microseconds, unfortunately; there's a fair amount of prologue going on. 5 posts • Page 1 of 1. However, IRQ latency is improved if late-arrival or tail-chaining has occurred. Initialize a 'direct' interrupt handler. None of them is induced by the abort in your modified esp_timer_impl_set_alarm code. 4, hd:ESP32-S3 when a pulse is detected by one io, an spi transaction will be triggered. I am seeing a similar issue as noted here:. When an interrupt is triggered, the processor halts the execution of the main program. The code is generated with this tool and modified for our test project requirements. We need to take some action when the interrupt is triggered (here: read a digital input). But if they are happening simultaneously, then the one with the higher priority runs first and the lower priority gets queued. GPIO Interrupt Latency - once more. Home; Quick links. esp32 GPIO interrupt latency. Through oscillometer I found the interval between the pulse and spi cs signal was as much as 100~200 us, while this thread says the interrupt latency can be reduced to about 2 us. You'll squeeze a few fractions of a us out of interrupt driven DMA, but that requires assembly coding the interrupt handlers (low latency interrupts in ESP32 require dropping the C runtime altogether) and Arduino. 4 GHz Wi-Fi (802. esp32 GPIO interrupt latency. and at T=9. 2 us (when the CPU frequency is 240 MHz and frequency scaling is not enabled). ESP32 GPIO Interrupts. GPIO Interrupt Latency - once more. An individual timer in a group should be identified with timer_idx_t. The Nano ESP32 features the ESP32-S3 system on a chip (SoC) from Espressif, which is embedded in the NORA-W106 module. Post by jfmateos » Mon Nov 07, 2016 9:03 am . RTOS task notifications can only be used when there is only one task that can be the recipient of the event. It also takes 26uS to process the IRQ body, though I am using QueueSendfromISR in the. Post by jeromeh » Sun Feb 05, 2017 8:31 am . But I'd guess that it is impossible to read. It also takes 26uS to process the IRQ body, though I am using QueueSendfromISR in the. After that you get a cylcetime of ~300ns (disable interrupts for core 0). common task congifuration. So far I got 3 additional cases with "Interrupt wdt timeout on CPU0" crashes. The interrupt source is a GPIO that connects to pulse-per-second signal from a GPS module. 35uS, the master brings the line high. Each interrupt has a fixed priority, most (but not all) interrupts are connected to the interrupt matrix. Each interrupt has a certain priority level, most (but not all) interrupts are connected to the interrupt mux. I will focus on describing how to refactor a. Post by MiguelMagno » Mon Aug 21, 2023 10:31 pm . The ESP32-S3 has a dual-core microprocessor Xtensa® 32-bit LX7, and has support for the 2. Quadrature Decoder Sensor. Choose the board, COM port, hold down the BOOT button, click upload and keep your finger on the BOOT button pressed. Skip to content. That's how power-supply short circuits are avoided. One way to get around this is to write a high-level interrupt in assembly, but that is non-trivial and I don't know if the Arduino environment supports it. It would be good to find a way to have interrupt handlers on the ESP32 have consistent and low latency. I have a strange problem with my ESP32 project. Home; Quick links. External Interrupt Latency. Setting a bit and polling this bit in another task within an infinite loop is faster (2 us), but cannot be a real option, because this is waste of resources and prevents from deep sleep options. greetings sdk: IDF V4. I think there has been a little bit of progress, although not specifically for this purpose: the GPIO drivers have been optimized a bit so if you use the ESP-IDF API, your interrupt latency should be a bit lower (but not as low as using the bare metal), and ESP-IDF now allows you to have high-prio assembly. 4 (brighnes and contrast enable)+. ESP32 GPIO Interrupts. I'm using the following code: Code: Select all. 9usec. I write the interrupt handler in assemble and register the interrupt in app_main with priority level 5. It also takes 26uS to process the IRQ body, though I am using QueueSendfromISR in the. On the ESP32, the Interrupt Allocation can route most interrupt sources to these interrupts via the interrupt mux. Post by jfmateos » Mon Nov 07, 2016 9:03 am . So my next step is to call an interrupt in assembly which required to use ESP32's higher priority levels. Now I have found the time to do it for myself and with the ESP32 and some other platforms. Enabling power management features comes at the cost of increased interrupt latency. esp32 GPIO interrupt latency. The MIPS chip I'd like to replace currently does it in 225 ns at 80 MHz (18 clock cycles), and any increase is likely to make things no longer work. Each interrupt has a certain priority level, most (but not all) interrupts are connected to the interrupt mux. Re: Critical attention to GPIO interrupts. INUM_GPIO (4) is the index for a GPIO interrupt, and this bit will be set in INTERRUPT if a GPIO interrupt has occured. For interrupt handlers which need to execute when the cache is disabled (e. The ESP32 is communicating with a PIC16 microcontroller through an I2C bus. The problem is: there is some delay between the interrupt being triggered and our taking the appropriate action. The following libraries are used: /* Libraries */ // Include WiFi Library #include <WiFi. Don't expect any miracles (and especially not 10-20ns); because of the Xtensa architecture, handling interrupts in C is pretty costly. Now I have found the time to do it for myself and with the ESP32 and some other platforms. Re: EXTI interrupt latency on STM32. Setting a bit and polling this bit in another task within an infinite loop is faster (2 us), but cannot be a real option, because this is waste of resources and prevents from deep sleep options. The cores in the ESP32 are labeled “Core 0” and “Core 1. The most common types of IRQ pins are dedicated external interrupt pins and IOC (interrupt-on-change) pins. Writing into a queue in order to handle the interrupt in another task takes way too much time (about 13 us). When the timer finishes. This routine initializes an interrupt handler for an IRQ. Is there a way (if possible code please) to improve it with some. Writing into a queue in order to handle the interrupt in another task takes way too much time (about 13 us). We’ll cover how to publish to a single field and how to publish to multiple fields. When PCIE0 (bit 0) is set, then the. Lately, I've been working on a project that consists of programming a Z80 with 8 address and data lines, the clock is done with ledc, it has two external interrupts on the Z80's WR and RD pins --> ESP32. When the timer finishes counting down, the LED automatically turns off. Home; Quick links. Sensor Shell Module Sample. Overview The ESP32-C3 has one core, with 31 interrupts. ESP_PM_APB_FREQ_MAX. The ESP32 has two cores, with 32 interrupts each. Espressif ESP32 Official Forum. g. For some reason, the traceback for case C could not be decoded by EspExceptionDecoder. GPIO Interrupt Latency - once more. Espressif ESP32 Official Forum. :49 am. Top. 35uS, the master brings the line high. Lately, I've been working on a project that consists of programming a Z80 with 8 address and data lines, the clock is done with ledc, it has two external interrupts on the Z80's WR and RD pins --> ESP32. In ESP-NOW, application data is encapsulated in a vendor-specific action frame and then transmitted from one Wi-Fi device to another without connection. These ESP32-C3 Hardware Timers, using Interrupt, still work even if other functions are blocking. Choose the board, COM port, hold down the BOOT button, click upload and keep your finger on the BOOT button pressed. It also supports tasks having “no affinity,” which means the task can run on either core. Each interrupt has a fixed priority, most (but not all) interrupts are connected to the interrupt matrix. Maximum voltage for low input is 0. The other running processes (on both processors) delay my normal C based interrupt (ESP_INTR_FLAG_LEVEL3) to make the detection vary by up to half a millisecond. The problem is that I want to reduce the current latency time I have (2 ms). That's. I have no idea what the latency would be without. Calling a C function from an interrupt requires the CPU's context to be saved, and the call stack to be switch to that of the C ISR. The following optimizations improve the execution of nearly all code, including boot times, throughput, latency, etc: Set CONFIG_ESPTOOLPY_FLASHMODE to QIO or QOUT mode (Quad I/O). Arduino Wiring-based Framework for the Espressif ESP32, ESP32-S and ESP32-C series of SoCs. In the attached "interrupt. A event handler is registered and can be called correctly, but the. Official development framework for ESP32 chip. Re: Comment about low-latency interrupts #52669. Yes, but for filling a beaker I doubt a few microseconds will matter. This library enables you to use Interrupt from Hardware Timers on an ESP32-C3-based board. implement hard pin interrupts on the esp32 to enable faster response times; check for pending soft interrupts in sleep_us(); this would need to be done in a smart. This library enables you to use Interrupt from Hardware Timers on an ESP32-C3-based board. At 17uS, the esp32 responds to the event and sets an IO line to respond, which is too late. A driver can allocate an interrupt for a. How to improve interrupt latency with Arduino/C. 2 Interrupt Service Routine (ISR) Handling. Interrupt low Latency - again. Post by go4retro » Thu Jan 10, 2019 6:26 am . Re: External Interrupt Latency. A event handler is registered and can be called correctly, but the. An stm32 is "worse" in a sense that you can easily use the arduino IDE to work with esp32, but it is different with stm chips. External Interrupt Latency. The difference is that dedicated external IRQ pins have separate interrupt vectors, while IRQ IOC pins share a common interrupt signal and you have to manually check which pin state has changed and caused that IOC global flag to. 04 in a VirtualBox. h> #include <HTTPClient. In this last example project, we’ll test multiple Arduino Timer Interrupts. But this is only applicable if you are using some of the RF features such as Wi-Fi or BLE. At 17uS, the esp32 responds to the event and sets an IO line to respond, which is too late. Espressif Homepage;. Use it with a scope or a logic analyser: 2700000 served interrupts/s greetings. This assumes that the interrupt handler is in cache or ITIM. Use this function if an RTC IO needs to be disconnected from internal circuits in deep sleep, to minimize leakage current. On the ESP32, the Interrupt Allocation can route most interrupt sources to these interrupts via the interrupt mux. Now I have found the time to do it for myself and with the ESP32 and some other platforms. 2 posts • Page 1 of 1. Postby Xtensa2C » Sun May 31, 2020 9:56 am. Setting a bit and polling this bit in another task within an infinite loop is faster (2 us), but cannot be a real option, because this is waste of resources and prevents from deep sleep options. Writing to those pins from the software will still trigger interrupt signals, which is also considered as software interrupts. Andreas’s test method uses the ESP32 SDK via Arduino IDE. Post by ESP_igrr » Mon Nov 07, 2016 11:36 am . I am seeing a similar issue as noted here:. within the loop, the WiFi connection just sits idle in the background. These interrupts are defined as zero-latency interrupts. Use vTaskSuspend () at the start of the loop to have the task wait till it's woken up. I measured the pin with an oscilloscope. Post by ESP_igrr » Mon Nov 07, 2016 11:36 am . Now I have found the time to do it for myself and with the ESP32 and some other platforms. g. Setting a bit and polling this bit in another task within an infinite loop is faster (2 us), but cannot be a real option, because this is waste of resources and prevents from deep sleep options. The arduino IDE completely abstracts the linking, interrupt tables and all that. Espressif ESP32 Official Forum. I can not figure out how to remove buffer or increase size to as close as possible real time transmission. Extra latency depends on a number of factors, such as the CPU frequency, single/dual core mode, whether or not frequency switch needs to be done. ESP32-S3 GPIO interrupt latency is too high. I am seeing a similar issue as noted here:. Imagine now that we have an interrupt being fired when the signal goes low to high. To use FreeRTOS timers, you have to turn them on with the following entry in FreeRTOSConfig. IRQ Startup latency. esp32 GPIO interrupt latency. None of them is induced by the abort in your modified esp_timer_impl_set_alarm code. For Cortex-M3/M4, the whole latency this process takes is 12 cycles. Install Drivers - Allocating ESP32’s resources for the UART driver. :49 am. 04 in a VirtualBox. A high interrupt latency, however, may not be acceptable for certain low-latency use-cases. This behavior was not happening with a Arduino Nano, I wanted to replace the nano with the ESP32. 2 posts. External Interrupt Latency. When I trigger an interrupt during the delay function the interrupt stops working. Post by ESP_igrr » Mon Nov 07, 2016 11:36 am . There the latency varies between 4us and 38us. void IRAM_ATTR isr_handler(void *ctrl) {. Home; Quick links. The code in loop is simply to output to the user, and like with External Interrupts, loop can simply inspect the interrupts flag, and perform an action based on this as needed. The Nano ESP32 features the NORA-W106-10B stand alone radio module, embedding an ESP32-S3 series SoC as well as an embedded antenna. Enable some one-off interrupt, such as GPIO interrupt. sdk: IDF V4. It also takes 26uS to process the IRQ body, though I am using QueueSendfromISR in the. 9usec. Register; Logout; Contact us; Board index English Forum Explore General Discussion; Interrupt low Latency - again. Put your current code from gpio_isr_handler () in a task in an infinite loop with a , start the task in app_main () and have gpio_isr_handler () just wake the task. Depending on the project at hand I switch between two development environments: either ESP-IDF, running under Eclipse on Ubuntu 18. Interrupt Latency Requirements Encoder requires low latency response to changes of the signals. :49 am. Obviously, cli() function is similar to noInterrupts() function. Deleting a Driver - Freeing allocated resources if a UART communication is no longer required. Maximum voltage for low input is 0. Because there are more interrupt sources than interrupts, sometimes it makes sense to share an interrupt in multiple drivers. Available now!Ever since I finished working on the latency tests & improvement, I've been working on trying to free up the 2nd core from its FreeRTOS duty by running it bare metal as originally demonstrated by @Daniel with #Bare metal second core on ESP32. IRQ Startup latency. Depending on the project at hand I switch between two development environments: either ESP-IDF, running under Eclipse on Ubuntu 18. Two main reasons: Interrupt Latency. Timer Initialization . Overview The ESP32 has two cores, with 32 interrupts each. Pete. IRQ Startup latency. ISR inside a class as a static class function with static variables. se » Wed Jun 16, 2021 9:17 am. 15. 15 postsWriting into a queue in order to handle the interrupt in another task takes way too much time (about 13 us). ESP_igrr Posts: 1970 Joined: Tue Dec 01, 2015 8:37 am. But technically the edge detection inside the CPU stores the values in a register somewhere and compares them to figure out if an edge occured between cycles. 35uS, the master brings the line high. Setting a bit and polling this bit in another task within an infinite loop is faster (2 us), but cannot be a real option, because this is waste of resources and prevents from deep sleep options. And it’s usually expressed in CPU clock cycles or time (in μs or ns). They are all 64-bit (54-bit for ESP32-C3) generic timers based on 16-bit pre-scalers and 64-bit (54-bit for ESP32-C3) up / down counters which are capable of being auto-reloaded. Post by jeromeh » Sun Feb 05, 2017 8:31 am . Use it with a scope or a logic analyser: 2700000 served interrupts/sgreetings. SPI Latency. I would like to know the interrupt latency for an external pin interrupt in ESP32. Re: External Interrupt Latency. First, interrupt handlers need to be defined using the IRAM_ATTR attribute in order to ensure that they're already loaded into instruction memory (IRAM). greetings sdk: IDF V4. Espressif ESP32 Official Forum. At 17uS, the esp32 responds to the event and sets an IO line to respond, which is too late. I need a <1usec resolution to read the outputs of CMPSS on the comparator section and be ready to read again those outputs after 1usec. Writing into a queue in order to handle the interrupt in another task takes way too much time (about 13 us). Each interrupt has a programmable priority level. Writing into a queue in order to handle the interrupt in another task takes way too much time (about 13 us). 25VDD and the minimum voltage for the high input os 0. Espressif ESP32 Official Forum. Extra latency depends on a number of factors, such as the CPU frequency, single/dual core mode, whether or not frequency switch needs to be done. The esp_intr_alloc () abstraction exists to hide all these implementation details. Depending on the project at hand I switch between two development environments: either ESP-IDF, running under Eclipse on Ubuntu 18. The ESP32 has two cores, with 32 interrupts each. I have a strange problem with my ESP32 project. An esp32 can do the job but is overkill and will be adding a complexity you do not need when learning C. Setting a bit and polling this bit in another task within an infinite loop is faster (2 us), but cannot be a real option, because this is waste of resources and prevents from deep sleep options. GPIO Interrupt Latency - once more. The Full code Listing. 35uS, the master brings the line high.