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Usage of Twi_Scanner-Example impossible

Ray Breslin

Hello,

I am was playing around a bit with the twi_scanner-example and I figured out, that no matter if I chose the legacy-layer with nrf_drv_twi-functions or the new nrfx_twi-functions I am always getting NRF_SUCCESS-messages on all I2C-addresses available, indicating that a device was successfully found.

Tried that with rx-/tx-functions likewise and also on the nRF52832-/nRF52840-DK including our own custom boards.

Even though I have just 1 specific sensor attached to the I2C-bus it shows possitive findings on all addresses, which makes the scanner-functionality obviously useless...

On the other hand I am able to successfully configure, read and transmit the sensor data with S132-/S140-softdevice-based-examples.

Is there anything I might be forgetting!?

Additional note: The plain twi_scanner-Example shows no results at all on the respective DKs with a sensor connected.

Kind regards,

Ray

  • 0

    Hi Harald,

    You are correct that this is not the intended behaviour.

    I would recommend you to take a look in this thread for NRFX_TWI driver.

    Here is a thread with some explanation regarding nrfx_twi and such, which I recommend you to take a look at.

     

    What pins do you have the sensor connected?

     The default pins are configured in pca10040.h : 

    #define ARDUINO_SCL_PIN             27    // SCL signal pin
#define ARDUINO_SDA_PIN             26    // SDA signal pin

    Have you connected a scope to check what is going on the bus?

    What kind of sensor is it?

     

     

  • 0 in reply to Martin Lesund

    Hello Martin,

    I am well aware of the I2C-configuration and how it is handled in the twi_scanner-example.

    For various projects I have been using the nRF52 SDK and I never had trouble with the I2C-communication so far, just until now when I was about to finish the portation from SDK v13.0.0 to SDK v15.0.0.

    So here is the scenario:

    1. I am using the nRF52832-DK with an inertial-sensor connected to the pins 26 and 27, then I run the twi_scanner-example and as a result I see this:

    <info> app: TWI scanner started.
    <info> app: No device was found.

    2. Tried the same thing on the nRF52840-DK with similar results.

    3. I changed the pin-configuration to various different unused gpios to see what is happening but I cant see no change in the behaviour.

    4. When I run the same code from the twi_scanner-example inside my own project-code - where I am able to successfully communicate with the inertial-sensor on any pin I want to - then I see quite the opposite from 1. since it shows available I2C-devices on all 127 I2C-addresses.

    I can insure you I have double checked every available code-line, the migration-guides and pretty much all the problem-topics in the forum regarding a proper I2C-setup with either the legacy-drivers nrf_drv_twi or the new nrfx_twi/nrfx_twim drivers.

    Still I cant figure out what the problem is... maybe I am too blind due to all the code-checking and research.

    The best part is - as a side note - that whenever I flash the twi_scanner-example my UART works, but no matter if I do a full erase or even a recover I am not able to get the UART back running with any ble- or softdevice-related example.

    Again something for the mystery department it seems...

  • 0 in reply to Ray Breslin

    Hi Harald,

    •  What specific inertial-sensor do you use?
    • in (1) you are using the unmodified twi_scanner example from SDKv15? Do you get a different result if you try one of the twi_scanner examples from one of the older SDK versions?
    • (4) What modifications do you have for your twi_scanner-example inside your own project code? (is this the code ported from sdk13-15?)

      Could you send your project so I could take a look? What specific Sensor are you connecting to the DK? (I would like to try to reproduce your issue)

    The side note: When you say "with any ble- or softdevice-related example.",(ble stack = softdevice, so if you are going to use ble-examples you have to flash the softdevice) are you pointing to the examples in the SDK? Do you not get any UART data when you run the "ble_app_uart" example?

     

    Best Regards,

    Martin L.

  • 0

    "Additional note: The plain twi_scanner-Example shows no results at all on the respective DKs with a sensor connected."

    Not sure what your environment is but i did see the same thing using  both nRF52832/nRF52840-DK, and SES 3.40 on OSX.. 

    It seems the issue (at least for me), is having NRF_LOG_BACKEND_UART_ENABLED set to 1. 

    Disable NRF_LOG_BACKEND_UART_ENABLED and enable NRF_LOG_BACKEND_RTT_ENABLED to see the output

  • +1

    Hi Harald,

      There does not seem to be something wrong with the unmodified "twi_scanner" example from the SDKv15.

    I just tested it with a sensor shield and received the addresses for two sensors.

    I suggest you download a fresh copy of SDKv15 and make sure to use the unmodified "twi_sensor" example and hook up the sensor to the correct pins.

    If you get "no devices found", my hunch is that either its the wrong pins or something is not getting power.

    Could you take a picture of you set-up, and share the details of your twi sensor please?

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