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terminator0o0
Level 1
Level 1
First solution authored First reply posted First question asked

Hi,

I am trying to communicate with the Optiga Trust X over i2c. I read the documentation and the power up cycle, however I get NACKs from the device. I have the ability to toggle the reset signal.

I have done repeated reads from the device because it goes in lower power mode but no luck with getting an acknowledgment.

Here is the waveform:

i2c_no_ack.PNG

More information can be provided.

Thanks for your help.

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1 Solution
terminator0o0
Level 1
Level 1
First solution authored First reply posted First question asked

I got the communication to work. I am not sure if this is a factor but I was waiting 120ms after the device reset to write to the device. Once I reduced it to 20ms, I got the acknowledgment. The datasheet doesn't specify the maximum time after the device reset but only the minimum (15ms).

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2 Replies
terminator0o0
Level 1
Level 1
First solution authored First reply posted First question asked

I got the communication to work. I am not sure if this is a factor but I was waiting 120ms after the device reset to write to the device. Once I reduced it to 20ms, I got the acknowledgment. The datasheet doesn't specify the maximum time after the device reset but only the minimum (15ms).

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Karishma_S
Moderator
Moderator
Moderator
50 solutions authored First comment on blog 250 sign-ins

Hi @terminator0o0,

The OPTIGA™ Trust X will not acknowledge the slave address sent by a host if it is either busy or in idle state. Hence the host must retry or repeat the transaction until it is successful or timed out for 100 milliseconds (extreme case).
The chip always goes into an idle or sleep state if no command is issued in a defined time period, unless a Sleep Activation Delay isn't changed.

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