delay() function doesn't work for less than 10ms

[ducalex]

Hardware:

Board: Lolin32
Core Installation version: d5fdd71
IDE name: IDF component
Flash Frequency: 40Mhz
PSRAM enabled: no
Upload Speed: 115200
Computer OS: Windows 8.1

Description:

delay() doesn't work for periods smaller than one tick(10ms) (it is also rounded down if not divisible by 1 tick).

It is a small change but I can create a pull request if it is the proper way to do things also, just tell me.

Sketch: (leave the backquotes for code formatting)

Current code is:
void delay(uint32_t ms)
{
    vTaskDelay(ms / portTICK_PERIOD_MS);
}



//  My suggestion is:
void delay(uint32_t ms)
{
    uint32_t delay_end = millis() + ms;
    vTaskDelay(ms / portTICK_PERIOD_MS);
    while (delay_end > millis()) {
        NOP();
    }
}

[stickbreaker]

@ducalex
Why do you think portTICK_PERIOD_MS is 10?

Chuck.

[stickbreaker]

@ducalex if you are worried the portTICK_PERIOD_MS will change in the future, then you could change delay() current Delay coding
to:

void delay(uint32_t ms)
{
    vTaskDelay(ms / portTICK_PERIOD_MS);
    uint32_t remainderUS = (ms % portTICK_PERIOD_MS)*1000;
    if(remainderUS) delayMicroseconds(remainderUS);
}

[ducalex]

@ducalex
Why do you think portTICK_PERIOD_MS is 10?

Chuck.

#define CONFIG_FREERTOS_HZ 100
#define configTICK_RATE_HZ				( CONFIG_FREERTOS_HZ )
#define portTICK_PERIOD_MS			( ( TickType_t ) 1000 / configTICK_RATE_HZ )\

vTaskDelay's argument is a tick number. Therefore it works correctly only on multiples of portTICK_PERIOD_MS which is 10.

Your code would also resolve the problem indeed.

[ducalex]

You can see the problem with this code:

void setup()
{
    for (int i = 0; i < 20; i++) {
        int start = millis();
        delay(i);
        printf("i = %d, actual sleep = %dms\n", i, (int)(millis() - start));
    }
}

Output:

i = 0, actual sleep = 0ms
i = 1, actual sleep = 0ms
i = 2, actual sleep = 0ms
i = 3, actual sleep = 0ms
i = 4, actual sleep = 0ms
i = 5, actual sleep = 0ms
i = 6, actual sleep = 0ms
i = 7, actual sleep = 0ms
i = 8, actual sleep = 0ms
i = 9, actual sleep = 0ms
i = 10, actual sleep = 7ms
i = 11, actual sleep = 10ms
i = 12, actual sleep = 10ms
i = 13, actual sleep = 10ms
i = 14, actual sleep = 10ms
i = 15, actual sleep = 10ms
i = 16, actual sleep = 10ms
i = 17, actual sleep = 10ms
i = 18, actual sleep = 10ms
i = 19, actual sleep = 10ms

[negativekelvin]

arduino-esp32/tools/sdk/include/config/sdkconfig.h

Line 229 in b0d8d4d

#define CONFIG_FREERTOS_HZ 1000

So I assume you are using arduino-esp32 as a component with your own sdkconfig settings?

Let's say portTICK_PERIOD_MS = 10 and you call delay(9). Do you really want to block and spin for 9ms?

[stickbreaker]

@ducalex with current core 7dbda4

to console i = 0, actual sleep = 0ms
to console i = 1, actual sleep = 1ms
to console i = 2, actual sleep = 2ms
to console i = 3, actual sleep = 3ms
to console i = 4, actual sleep = 4ms
to console i = 5, actual sleep = 5ms
to console i = 6, actual sleep = 6ms
to console i = 7, actual sleep = 7ms
to console i = 8, actual sleep = 8ms
to console i = 9, actual sleep = 9ms
to console i = 10, actual sleep = 10ms
to console i = 11, actual sleep = 11ms
to console i = 12, actual sleep = 12ms
to console i = 13, actual sleep = 13ms
to console i = 14, actual sleep = 14ms
to console i = 15, actual sleep = 15ms
to console i = 16, actual sleep = 16ms
to console i = 17, actual sleep = 17ms
to console i = 18, actual sleep = 18ms
to console i = 19, actual sleep = 19ms

Chuck.

[ducalex]

So I assume you are using arduino-esp32 as a component with your own sdkconfig settings?

Correct, the default esp-idf settings.

Let's say portTICK_PERIOD_MS = 10 and you call delay(9). Do you really want to block and spin for 9ms?

I do. That is how other arduino boards work and a lot of code and libraries expect delay to work as per the documentation.

That is also how esp-idf's own usleep() works.

As you pointed out delay works fine in Arduino IDE, if you consider Arduino as component to be unsupported then please close this issue!

Thanks

[ducalex]

@stickbreaker Yes, I can see it works fine in Arduino IDE now. As pointed out by @negativekelvin, it is only a problem when using arduino-esp32 as a component because freertos frequency is 100hz (by default).

[stickbreaker]

I missed you were using arduino as a component. I don't know all the rules when using arduino as a component. I do know, I2C is not shared between Wire() and idf.

Chuck.

[negativekelvin]

I do. That is how other arduino boards work and a lot of code and libraries expect delay to work as per the documentation.
That is also how esp-idf's own usleep() works.

Yes usleep, emphasis on the u. It is not good design to use it for ms delays. Is there a reason you don't want to set tick hz to 1000?

[ducalex]

Is there a reason you don't want to set tick hz to 1000?

None, I didn't know that Arduino-esp32 IDE version wasn't using the default 100Hz.

I will change my project to 1000 but perhaps it could be worth mentioning this necessary step in the setup guide here https://github.com/espressif/arduino-esp32/blob/master/docs/esp-idf_component.md.

Thanks

[romansavrulin]

@ducalex Please fix that doc to and make a PR

[ducalex]

Done. #3014

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