[RTOS][esp-idf] ESP32 interrupts and shuffles some basic questions

Question

Hi I have a couple of questions about esp32 and the RTOS that appears in it 1)Is it true that when using interrupts (e.g. from a timer), the best practice is to make them only wake up the task that does all the work? Because the fact that ISRs are supposed to be the shortest is obvious, but are...

Anonymous · Accepted Answer

. This is such an unholy tradition among those who program with ESP-IDF It all depends on how critical shuffles are to be implemented in the ISR - if very and short, it is better to stay with just interrupts. . This is what you should stick to. . If the timeout resolution is 1ms, then the scheduler cannot automatically call (and actually queue) tasks more frequently, but ... you can force a task to execute if some conditions are met, e.g. in case of conversion from ISR or in the task itself to force its earlier, next iteration. . If these are interrupts from esp_timer, then by default the ISRs are already converted to shuffles, and there is basically one esp_timer task that controls the ISR calls from esp_timer. The priority of this task is equal to ESP_TASK_PRIO_MAX - 3, which is quite high. You would have to enable CONFIG_ESP_TIMER_SUPPORTS_ISR_DISPATCH_METHOD in sdkconfig to make it ISR-only - by default this option is disabled. Unfortunately this option is only available in version 4.3 of ESP-IDF, which is not yet marked as stable for the time being. . Since you switched from AVR, you are no longer erring . . You simply switch between tasks, one of which is esp_timer.

Anonymous · Accepted Answer

Reduce the execution time of the set_catode() and interrupt_from_timer_mux() functions, i.e. instead of the free gpio_set_level() function, directly manipulate the GPIO W1TS registers once GPIO W1TC or (even faster) use the RMT controller (RMT channels can be mapped to any pins).

NIXIE_123 · Answer

. Yes, they are triggered by the timer. . I understand that the interrupt forces the esp_timer task to execute itself which is why it runs more than 1ms, and when I created a separate task and only woke it up with the timer it had to wait for each subsequent tick of the system i.e. 1ms . The mentioned function running every 35µs multiplexes the display in the nixie watch. It has to be so often because it supports 6 lamps, a crossfade effect and 1/6 pwm dimming. I didn't want it to, for example, hinder the processor from handling the wi-fi connection I want to add in a while. It's not super critical somehow but it has to execute frequently otherwise you can see the multiplexing. Since . then it probably won't be a tragedy.

Anonymous · Answer

. Exactly. . This is where I have to worry you a bit. The documentation for IDF version 4.2 talks about a minimum time of 50µs: .

NIXIE_123 · Answer

I have this problem: An interrupt from the timer every 111µs interferes with the wifi connection. A panic is created. I just uncomment the initialization of the timer and all the code works. The other way when I throw away the wifi connection and leave the timer also everything works. I tried first with a simple example_connect(); and now with a full-fledged station mode. Always the same effect. The timer works nicely only the addition of wifi remains

Anonymous · Answer

As I wrote earlier interrupts from esp_timer are converted to high priority RTOS threads. This is a higher priority (22) than for WiFi handling functions. Question one: how long does it take to handle a single esp_timer thread? Question two: does the problem only occur at WiFi initiation (STA or AP) or also during WiFi operation? By default, esp_timer and WiFi handling are executed on the same Core 0 (PRO_CPU), so they fight for resources and esp_timer always wins.

NIXIE_123 · Answer

. How to check this? The interrupt is a bit of variable and port setting. . So far I have not started the watch with wifi so on initiation. I would like there to be no conflict even at initiation because the clock will sync every half hour and it won't always have access to the wifi network. I don't want workarounds like turning off the display for sync time etc. . Well, that's right, after all this hardware has two cores. Can it be split into two? That was probably the designers' intention. One core for the program and the other for wifi and bluetooth

Anonymous · Answer

. Using the esp_timer_get_time() function. . If some functional part of the program should be executed on a specific Core, it should be in the task handler, which is pinned to a specific Core - xTaskCreatePinnedToCore(). To start with, however, I would suggest measuring the execution time of a single callback function assigned to an interrupt with esp_timer.

NIXIE_123 · Answer

Code: C / C++Log in, to see the code . every 200ms ESP_LOG with time value Stands at 5µs. Occasionally peaks to 8 top 10

Anonymous · Answer

Is the interrupt_from_timer() function an ISR callback for esp_timer, or for timer_group? It looks like the latter.

NIXIE_123 · Answer

Code: C / C++Log in, to see the code .

Anonymous · Answer

. Could you please post this message in full? But already after the exception decoder.

NIXIE_123 · Answer

Exception decoder I found only for arduino. I downloaded arduino IDE but when I paste the code it sees the library from wifi but still there are errors from wifi and it doesn't compile. I guess there is no point in doing the code under arduino because there will be another exception or it will work. .

Anonymous · Answer

Which IDE are you using? For PlatformIO there is also

NIXIE_123 · Answer

.

Anonymous · Answer

There is a PlatformIO plugin for eclipse, and this is probably the only way you will have access to the Exception Decoder: Link . Without this tool, it's really hard to catch the causes of program crashes. Alternatively, if you have one, you can use the ESP-PROG debugger, but that will be more difficult. Added 5 [hours] 20 [minutes]: Actually with the timer on, it crashes, but much earlier, with nvs_flash_init(): Code: BashLog in, to see the code . As I increased the alarm_value in timer_set_alarm_value() to 10ms, it works fine (I had previously increased CONFIG_FREERTOS_HZ to 1000 in sdkconfig). Something is wrong in the configuration of the timer itself, but today I don't have the strength to go into it further. . And I don't believe this after reviewing the code of the interrupt_from_timer_mux() and set_catode() functions. Sorry . Added after 45 [minutes]: Yes, as I sensed there was an error in the timer configuration. With this configuration:Code: C / C++Log in, to see the code andCode: C / C++Log in, to see the code WiFi works correctly. At least with me . You also have a bug in your program: the set_catode() function also needs to be IRAM_ATTR.

NIXIE_123 · Answer

Thank you for leaning into my case. . Unfortunately with a divider of 10,000 the interrupt will be triggered every 13.875ms rather than 111µs 80MHz/10 000 = 8kHz 1/8kHz = 125µs 125µs * 111 = 13.875ms And I need 80MHz/80 = 1MHz 1/1MHz = 1µs 1µs * 111 = 111µs

Anonymous · Answer

I performed a simple test. I used the simplest possible callback function for the timer:Code: C / C++Log in, to see the code With divider=80 and timer_set_alarm_value(TIMER_GROUP_0, TIMER_0, 111) the program works fine. So the problem is the interrupt_from_timer_mux() function itself - its execution time and the occupancy on the stack for the ISR, which is limited to 1536 bytes by default (CONFIG_FREERTOS_ISR_STACKSIZE). . At least five times longer executes, but I leave that to you for further analysis. If this callback is actually supposed to execute every 111µs, then its execution time should not exceed 10µs - so as to give the opportunity for other processes to do any work, including TWDT.

NIXIE_123 · Answer

I repeated your test at my place and unfortunately it doesn't work at my place. Even after increasing CONFIG_FREERTOS_HZ to 1000 However, the whole clock works when I use Code: text Expand Select all Copy to clipboardtimer_isr_register(TIMER_GROUP_0, TIMER_0, przerwanie_od_timer, NULL, 0, NULL); . And it works even when I go down from 111µs to 35µs. Link . .

Anonymous · Answer

. But in this case without the ESP_INTR_FLAG_IRAM flag, so these interrupts will be blocked on every write to flash (WiFi functions use this too). What is then the realistic interval of these interrupts? Anyway, colleague ESP_Sprite also mentioned this . .

NIXIE_123 · Answer

Well yes, it is a workaround but it gives an interrupt which does nothing and there is still a conflict then what am I left with?

NIXIE_123 · Answer

But I have removed this function completely. The interruption does exactly nothing. Nevertheless, there is a conflict Code: C / C++Log in, to see the code

Anonymous · Answer

I don't understand this. With me with this simple callback function it works (I just checked). The fact that I am using ESP-IDF version 4.3. I also changed the order of execution of timer_isr_register() from timer_enable_intr():Code: C / C++Log in, to see the code . In contrast, it takes 7µs to execute the interrupt_from_timer_test() function.

NIXIE_123 · Answer

And which chip do you have? I esp32 rev. 1 wroom-32

Anonymous · Answer

Also WROOM-32 Code: BashLog in, to see the code .

mpier · Answer

Hello, I might hit you with a question: do timer_spinlock_take() and the rest have IRAM_ATTR to work without flash access? This is where I would look, maybe it can be done differently. Greetings.

NIXIE_123 · Answer

Very good point. After upgrading to esp-idf v4.3 this function is not found at all. In read the docs it says that this function is deprecated and use a better one. I am currently trying to come to terms after the upgrade.

Anonymous · Answer

. But not in the latest stable version 4.3, but in higher (master) versions. The functions timer_spinlock_take() and timer_spinlock_give() are IRAM_ATTR:Code: C / C++Log in, to see the code Responsible for entering and exiting to/from the critical section where other interrupts and threads are blocked. In my opinion it is better to use timer_isr_callback_add () instead of timer_isr_register(). Then in your own ISR callback you no longer need to create a critical section.Code: C / C++Log in, to see the code Callback from the interrupt will be called automatically in the critical section.

NIXIE_123 · Answer

. After upgrading to v4.3 it already works (empty interrupt) Now I have these circuses for a change: . . . Everything compiles 0 errors 0 warnings and it does not see the BUTTON_DOWN defined. Pressing ctrl and left button on an item not found flips me to it as if it sees it. The program loads and the clock now acts as a paper button.... My hands are falling off. I have already done a fullclean and a build but to no avail .

[Solved] [RTOS][esp-idf] ESP32 interrupts and shuffles some basic questions

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