Unable to interface PCF8574 with nr53DK.

RE: Unable to interface PCF8574 with nr53DK.

Navin — Tue, 14 May 2024 08:57:48 GMT

Hi Runar,

Thanks for response!

I found out what was wrong with my code. The address is supposed to be 0x20 and not 0x40, as it a 7-bit address. ST HAL API expects an 8-bit left shifted value, which confused me.

Here is an alternating pattern for:

uint16_t data = 0xAA55;

It works with the same DT binding I initially provided with the default arduino pins (P1.03 and P1.02).

&i2c1 {

mysensor: mysensor@20{

compatible = "i2c-device";

status = "okay";

reg = < 0x20 >;

};

Thanks again for pointing out the issue, it helped in figuring out the solution.

Best regards,

Navin

RE: Unable to interface PCF8574 with nr53DK.

runsiv — Mon, 13 May 2024 12:47:01 GMT

If you have a look at the device binding which you can find here, you will see that you are missing a few field

It should look something similar to this

&i2c {
  status = "okay";
  pcf8574: pcf857x@20 {
      compatible = "nxp,pcf857x";
      status = "okay";
      reg = <0x20>;
      gpio-controller;
      #gpio-cells = <2>;
      ngpios = <8>;
  };


};

If you are using the newest version NCS the Kconfig should be CONFIG_GPIO_PCF857X=y

Regards

Runar

RE: Unable to interface PCF8574 with nr53DK.

Navin — Mon, 13 May 2024 10:22:07 GMT

Hi Runar,

Thank you for the response!

Here is prj.conf

#
# Copyright (c) 2016 Intel Corporation
#
# SPDX-License-Identifier: Apache-2.0
#

# STEP 2 - Enable the I2C driver
CONFIG_I2C=y
# STEP 4.2 - Enable floating point format specifiers
CONFIG_CBPRINTF_FP_SUPPORT=y
CONFIG_LOG=y

And here is the DTS overlay:

&i2c1 {

    mysensor: mysensor@40{
        compatible = "i2c-device";
        status = "okay";
        reg = < 0x40 >;
    };
};

Also, please find the final zephyr.dts

devzone.nordicsemi.com/.../6116.zephyr.dts

Best regards,

Navin

RE: Unable to interface PCF8574 with nr53DK.

runsiv — Fri, 10 May 2024 05:28:54 GMT

Hi Navin

Could you post your devicetree and your prj.conf?

Nb. We are a bit shorter staffed than usual at devzone due to today being a squeeze day in Norway (Friday after a national holiday) so the response time might be longer then usual.

Regards

Runar