iic can't read data but can write data

[refix]

1. Hi, I have some questions about i2c when I use

   i2c_write_read_dt(&dev_i2c,&config[0],1,&config[1],1);

   The data cannot be read correctly,

   i2c_burst_read_dt(&dev_i2c,0x08,temp_reading,sizeof(temp_reading));

   The data read will be shifted. I use nrf5340 audio dk to control max30210. How can I fix this? (已編輯)

   

   When I use this code, the data is not read correctly. I am using nrf5340 audio dk to control max30210. When I use a logic analyzer to observe the data, it seems that there is no waiting after ark when reading data. I'm not sure how to fix this issue.

[Jared]

Hi,

The data read will be shifted. I use nrf5340 audio dk to control max30210. How can I fix this? (已編輯)

That sounds very strange, could you share a full trace from the logical analyzer?

regards

Jared

[refix]

yes 

[Jared]

Hi,

I'm not sure why mean by the data being shifted but looking at the original data trace that you shared:

編輯)

It looks like the peripheral is sending a NACK after the read request.

Are you sure that you're requesting the correct read address to the slave?

regards

Jared 

[refix]

sure I think I requesting the correct read address.

and this picture is from MAX30210EVKIT Sensor Evaluation Kit data. 

regards
refix

[Jared]

Hi,

It looks like you're trying to write and then read out the same register from the I2C slave, is this correct?

It seems like the write is successful, but the slave return a NACK when you try to read out the same register later here:

From the nRF5340 perspective it looks correct. Maybe you need to wait some time before you can read out the register after writing. The read process should be specified in the datasheet of the slave device,

regards

Jared

[refix]

I think you are right but I don't know if Ruhe should wait for ACK when reading and then read the library I use is <zephyr/drivers/i2c.h>

overlay 

```

&i2c1 {

    clock-frequency = <I2C_BITRATE_FAST_PLUS>;

    mysensor: mysensor@40{

        compatible = "i2c-device";

        status = "okay";

        reg = < 0x40 >;

    };

};

```

regards
refix

[Jared]

Hi,

Have you tried just doing a separate read without any write before?

Are you able to read any other register from the slave?

[refix]

I have tried to read it individually, but if I read only one piece of data, most of it will not be useful data. In the continuous reading mode, I can read the data, but the first complement will not be correct. Just like I read the last three entries above, but only the last two entries are correct.

[Jared]

In the last three entries, what did you expect to read out? How exactly is it not correct?