Unable to detect a i2c sensor using twi_scanner example

[Prayjit]

I want to use a sensor with nrf52 dev kit. for the same purpose I am first scanning sensor using twi_scanner example but it does not detect.


configuration used for nrf_drv_twi_config_t is :

>>
    const nrf_drv_twi_config_t twi_config = {
       .scl                = 8,
       .sda                = 14,
       .frequency          = NRF_TWI_FREQ_250K,
       .interrupt_priority = APP_IRQ_PRIORITY_HIGH,
       .clear_bus_init     = true
    };

    err_code = nrf_drv_twi_init(&m_twi, &twi_config, NULL, NULL);


I have tried the .frequency as NRF_TWI_FREQ_250K, NRF_DRV_TWI_FREQ_100K, NRF_TWI_FREQ_400K and also checked on other GPIOs but still it did not worked.
I checked the same sensor with Ardunio and Raspberry Pi , there it works fine.

[Edvin]

Try using the default pins. I see that you have tested on different pins, but perhaps you were unlucky. Try to use pins 26 and 27, as these are not used by anything else by default. 

What does nrf_drv_twi_init() return? That is, what is err_code after nrf_drv_twi_init() is done executing?

Initializing the twi is something you need to do, but it doesn't start the scanning?

Did you leave the rest of the main.c file from the twi_scanner example unmodified? 

Best regards,

Edvin

[Prayjit]

First time I used the default pins , but it was unsuccessful. The rest part of the code is unmodified. 

Additionally I tried a different sensor , nrf scanner example detects it..

Problem is that the sensor which I want use for development is not getting dedicated. 

[Prayjit]

Similar issue found @ Case ID: 262861

https://devzone.nordicsemi.com/f/nordic-q-a/70402/twi-scanner-i2c-address-is-1-bit-wrong/290086

In above case nrf board is detecting sensor with wrong address but in my case its not getting detected for any address.

I already tried with external power supply

[Edvin]

Did you measure the voltage? Did you use a logic analyzer to check it? What is the minimum voltage requirement on the I2C/TWI on your sensor, according to the datasheet of your device? What device is it?

[Prayjit]

Supply Voltage VDD -0.3 to 5.5 V
Max Voltage on pins SDA, SCL, -0.3 to VDD+0.3 V

The device I am using is SDP3x

[Edvin]

https://www.mouser.com/datasheet/2/682/Sensirion_Differential_Pressure_Sensors_SDP3x_Digi-1511485.pdf

So do you use just the chip, or do you have a custom PCB or a breakout board for the sensor?

I know you probably will say that it is correct, but can you please check that you have connected the correct pins? SCL -> SCL,  SDA to SDA, VDD -> VDD and GND->GND?

Next, try to analyze the communication using a logic analyzer, and upload the trace here.

BR,
Edvin

[Prayjit]

I am using Evaluation Kit EK-P4

https://www.sensirion.com/en/flow-sensors/differential-pressure-sensors/test-your-sdp3x-differential-pressure-sensor-with-the-evaluation-kit-ek-p4/

So, I don't think there could be issue from PCB,

Same module I am able to use with ardunio board  and I am able to read i2c address as well as pressure readings from i2c bus of sensor.

In case of nrf board >> not even i2c address is also not getting scanned.
SCL -> SCL,  SDA ->SDA, VDD -> VDD and GND->GND are properly connected ..and tried may times

I used VDD as 3.3V and 5V for experiment

If we can try some modifications for scanning the device correctly by modifying  struct "twi_config" /  function "nrf_drv_twi_init" ??

[Edvin]

Have you tried debugging to ensure that the TWI functions are used are actually reached?

[Prayjit]

Yes..

Addition to this as mentioned already.. I am able to detect other i2c sensor ( like accelerometer) using same scanner code without any modifications

[Edvin]

Yes...

I am trying to figure out what the issue is, but I do not have access to the same TWI sensor that you are using. Therefore, if you are telling me that you are running the TWI scanner example and it isn't detected, I suspect that one of the two following things are happening:

1: The scanner part of the code is not reached. This can be easily checked by debugging and seeing that the nrf_drv_twi_rx() is reached with the address that you believe it is using, and that err_code = NRF_SUCCESS at that point in time (after err_code = nrf_drv_twi_rx() is executed).

2: The sensor, as it is detected by other microcontrollers, such as your arduino, requires a different voltage than what the nRF provides. Did you check your VDD with a multimeter? Depending on the arduino you were using, it may have different GPIO voltage. Perhaps it has 5V GPIOs? My suspicion is that the nRF GPIOs doesn't have a high enough voltage for your sensor.