Receiving NACK from the slave device after sending the slave address

[Nirupama]

Hi Nordic,

I have been trying to communicate with KX 124-1051 using IIC in nRF52832. I am getting NACK from slave every time i send the device address. I checked all the corner issues causing the NACK. Using the same board i tried with other sensors changing the slave address, i am able to read their chip ID. But its been failing with only this(KX 124-1051) sensor.Can anyone help me with this?

Thanks in Advance,

Nirupama.T

[awneil]

Are you sure that the slave is actively sending a NACK?

Remember that a NACK will be seen if there is no slave connected at all ...

Also, a NAK will be seen if the Slave simply ignores the address - which would be the case if you have the wrong address ...

Have you looked at the I2C lines with a scope or analyser ?

Have you tried the TWI Scanner ?

[Nirupama]

Yes, I checked many times. Even with TWI Scanner app, i was not able to detect the tag.  Under what conditions slave sends NACK even though address is correct? The slave address is 0x1E. This address is the correct one.

[awneil]

Nirupama said:

Even with TWI Scanner app, i was not able to detect the tag

Then there's something fundamentally wrong!

Have you looked at the I2C lines with a scope or analyser ?

Nirupama said:

Under what conditions slave sends NACK even though address is correct?

You would have to check the device's documentation for that.

Have you had this slave working with any other Master?

[Nirupama]

I haven't tested with any other master, Clock is also fine. But in the datasheet, they mentioned like
Note : if the accelerometer is accessed through I2C protocol before the startup is finished a NACK signal is sent.

This i didn't understand. Do you have any idea?

[awneil]

If you need clarification of 3rd-party documentation, then you need to contact the 3rd-party for that - it has nothing to do with Nordic!

It sounds perfectly clear to me - what bit don't you understand?

Presumably, the documentation tells you how long "the startup" can be expected to last?

So just wait a bit longer than that before trying to communicate with it!

[Nirupama]

I tried adding some delay for startup to complete. It didn't work out. And it is not even detected by TWI scanner. I have connected other sensors and they are getting detected. Why not this?