TWIM 1 Timeslot no interrupt

RE: TWIM 1 Timeslot no interrupt

Olfox — Mon, 11 Jul 2022 06:53:45 GMT

HI Sigurd,

I figure out that the problem of periodic interrupt and clapping to 490ms was coming from my sensor refresh rate. No w it workd properly without scheduling or timeslot.

I'm a bit disapointted to not have succed in using twim with timelot but i don't need it anymore.

Thanks for your help.

RE: TWIM 1 Timeslot no interrupt

Olfox — Sun, 03 Jul 2022 15:35:39 GMT

[quote userid="15146" url="~/f/nordic-q-a/89260/twim-1-timeslot-no-interrupt/375081"]Are you reading 1 and 1 byte?[/quote]

No i'm using Easy DMA with TWIM1 . Here is the function i'm using:

As it is 16bit register , i need to switch msb and lsb by using a for loop at the end of the function.

ret_code_t I2CRead(uint8_t slaveAddr, uint16_t startAddress, uint16_t nMemAddressRead, uint16_t *data){

    ret_code_t err_code; 
    uint8_t addr[2] = {0,0};
    uint16_t lsb,msb;

    addr[0] = startAddress >> 8;       //msb first
    addr[1] = startAddress & 0x00FF;   //lsb first


    const nrfx_twim_xfer_desc_t    my_xfer   =    {.type = NRFX_TWIM_XFER_TXRX,
                                                    .address=slaveAddr,
                                                    .primary_length   = 2,
                                                    .secondary_length = (nMemAddressRead<<1),
                                                    .p_primary_buf    = &addr,
                                                    .p_secondary_buf  = data
                                                  };

    err_code = nrfx_twim_xfer(&my_twi, &my_xfer ,0);
    APP_ERROR_CHECK(err_code);


    while(nrfx_twim_is_busy(&my_twi)){;}

    for(int i=0; i < nMemAddressRead; i++){

        lsb = (data[i]&0xff00) >> 8;
        msb=  data[i] &  0xff;
        data[i] = (msb<<8) | lsb;
    }

    return err_code;
  
}

[quote userid="15146" url="~/f/nordic-q-a/89260/twim-1-timeslot-no-interrupt/375081"]Are you in a connection when doing this test?[/quote]

Yes i'm connected when i read the sensor for sure.

[quote userid="15146" url="~/f/nordic-q-a/89260/twim-1-timeslot-no-interrupt/375081"]Have you tried increasing the connection interval?[/quote]

Yes here is my settings. But is doesn't impact the 184us periodic interval i see on scope. But i se impact on power consumption with PPK.

#define MIN_CONN_INTERVAL MSEC_TO_UNITS(100, UNIT_1_25_MS) /**< Minimum acceptable connection interval (0.1 seconds). */
#define MAX_CONN_INTERVAL MSEC_TO_UNITS(200, UNIT_1_25_MS) /**< Maximum acceptable connection interval (0.2 second). */

Remember, when i do this communication at the entry point of the program, just after main ( first operation) it takes only 45ms for this test.

So from what this periodic interrupt can comes from?

And did you already succed in using timeslot with twim please ?

As tried scheduler but it doesn't bring any advantages compared to execute in timer handler.

I'm losing a bit hope at the moment i hope you will have answer to this issue.

Thanks a lot

RE: TWIM 1 Timeslot no interrupt

Sigurd — Fri, 01 Jul 2022 11:59:36 GMT

Hi,

Are you reading 1 and 1 byte?

The TWIM peripheral have EasyDMA, https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52833%2Ftwim.html so you can transfer multiple bytes without CPU involvement.

[quote user=""]I guess Soft Device (s113 in my case) take this time. For example, communication that should take 13ms when no sd is running ( on the 45ms in total for my sensors tasks, rest is big float computation) takes 350ms ! 26 times the time it should ![/quote]

Are you in a connection when doing this test? Have you tried increasing the connection interval? Even as a BLE peripheral, you can request a higher connection interval. If you are advertising, try temporarily disabling the adverting.

RE: TWIM 1 Timeslot no interrupt

Olfox — Sun, 26 Jun 2022 15:50:41 GMT

Hi,

I finally tried the scheduler without improvement.

So i decided to check with the scope what happens during transmision when it is done into the main, but i it is the same effect in interrupt app timer handler.

It seems twim communication is interrupted each 184us, during 34us and sometime even more.

So iguess timeslot is the own solution.

RE: TWIM 1 Timeslot no interrupt

Olfox — Fri, 24 Jun 2022 08:42:38 GMT

Hi Sigurd,

I found the Einard tutorial concerning scheduler here:

nRF5 SDK Scheduler Tutorial

It confirms what i understood previouly but doesn't help me to undestand why i will be able to not be interrupted during my 45s sensor task (by SD i guess)

Even with scheduler, i don't see how it will avoid to increase my sensors task time from 45ms to 490ms.

A part of timeslot i don't see any other way in fact a the moment. May be Einarh have good argument too :D ?

Thanks a for your help

RE: TWIM 1 Timeslot no interrupt

Olfox — Thu, 23 Jun 2022 14:13:51 GMT

Hi Sigurd,

[quote userid="15146" url="~/f/nordic-q-a/89260/twim-1-timeslot-no-interrupt/373957"]1) What issue with the SD are you getting? Could you elaborate on that.[/quote]

I mean i had issue because the 45ms it should take was also taking too long in the interrupt timer and i'm not able to read caracteristic sometimes, program is stuck

[quote userid="15146" url="~/f/nordic-q-a/89260/twim-1-timeslot-no-interrupt/373957"]2) Did you try using the scheduler as suggest by Einar Thorsrud in your other post? [/quote]

To be honnest i look at it, but i was not convinced it would help more than the first proposal Einar did ( jut set a flag into the timer interrupt and check it into main() ). It looks complex compared than just a flag set and clear once done.

By studying the link you gave, i don't really see added value to the scheduler ( may be i don't see benefit because a lack of knowledge). So to deeply understand i compared both method but even with that, i don't clearly see how scheduler will avoid SD to take the lead.

A part of adding the orange time, what is the benefit on timing or how it could help with my issue ?

3) Also, why timeslot is not the most appropriate solution compared to scheduler for example? I have the feeling to do something really complex, but it is just communicate with a sensor and to be able to get a ble carac updated each max 100ms with my sensor data. Is it a special complex case ? I guess it is a common customer need no ?

May be timeslot is overkill in this case. I will be really happy to understand and being convinced that scheduler will help, can you guide me a bit more in detail on how to properly proceed in the big line please . I will start to learn about it on devzone because infocenter documentation is a bit light on this subject.

Thank a lot Sigurd for your help i hope to have this working really really soon.

RE: TWIM 1 Timeslot no interrupt

Sigurd — Thu, 23 Jun 2022 13:15:03 GMT

Hi,

[quote user="Olfox"]

Then how to proceed to be able to communicate with my i2c sensors during timeslot?

[/quote]

I don't think timeslot is suited for the issue you are trying to solve here.

[quote user=""]As i2c communication + computation takes 45ms in my timer interrupt that happen each 100ms and gave issue with SD[/quote]

1) What issue with the SD are you getting? Could you elaborate on that.

2) Did you try using the scheduler as suggest by Einar Thorsrud in your other post? Communicate with sensor in timer interrupt occurs issue

RE: TWIM 1 Timeslot no interrupt

Olfox — Thu, 23 Jun 2022 09:18:04 GMT

I tried to set interrupt from 2 to 0 but it is the same, still blocked on the while.

But i can see all the byte on twim line on my scope so the hardware/twim send fucntion works properly when called in the timeslot).

It is just the interrupt that seems to be not autorized.

i can confirm that by mentionning the soft device specification:

Then how to proceed to be able to communicate with my i2c sensors during timeslot?

I tried to replace while ( is busy) that wait for interuption by nrf(delay) even it is dirty, without succes yet. It is not really a solution but ...