I2C burst write for nRF5340 fails

[SamA]

I2C burst write for nRF5340 at 100kHz is failing with a reply of -5.   (Trying to use the BMI270 drivers sample, it will fail during reg_write of the configuration file)

Reading works. with nRF5340. I can read the Chip ID correctly. 

Same code on nRF52480 works perfectly. (Read and write). 

[Albrecht Markus Schellenberger]

Hello Samuel,

one difference between those two devices is that the nRF5340 is using TWIM drivers while the nRF52840 is using TWI drivers. TWIM has a hardware limitation which results in burst writes not all sensors are supporting. You can read more about this here. There is also a similar case in DevZone.

A good starting point could be to add the concat-buf-size attribute in an overlay file and check if that makes any differences. Below you can see an example of the attribute usage:

/*
 * Copyright (c) 2021 Bosch Sensortec GmbH
 *
 * SPDX-License-Identifier: Apache-2.0
 */
&arduino_i2c {
    status = "okay";
    zephyr,concat-buf-size = <128>;
    bmi270@68 {
        compatible = "bosch,bmi270";
        reg = <0x68>;
        label = "BMI270";
    };
};

I hope this will help you!

Regards,

Markus

[SamA]

Great, will experiment more. ! thanks

[SamA]

Sorry for reporting back late.. the concat-buf-size = <128>; worked.   I had to tune it to fit my array size.