S32K use rtd set I2C

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S32K use rtd set I2C

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jianqun
Contributor I

I used hardware I2C to set 400K baud rate. The waveform was normal, but there were problems in the communication with the slave machine. Some data could be written and read out normally, while some were abnormal. I suspect the I2C timing is not well configured. Is there any documentation about this? How to set the parameters in the red box? The driver that used RTM before calculated the configuration by itself

1.png2.png3.png52.png

 

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3 Replies

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danielmartynek
NXP TechSupport
NXP TechSupport

Hello @jianqun,

Please refer to the RM rev. 14, Section 52.3.2.4 Timing Parameters.
As you can see, the SCL clock period depends on the bus latency as well, which is given by the capacitance of the bus and the size of the pull-up resistors.

The RTD does not calculate with the parameters of the bus.

You will get slightly different bit rate if you use different pull-ups.

 

Regards,

Daniel

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jianqun
Contributor I

jianqun_0-1669274048171.png

I changed the pull-up resistance from 4.7K pull-up to 2.2K pull-up and found that the speed of 400K did not improve the waveform much

  • I want to try a 100K rate

Can the I2C parameter of RTD provide a setting parameter of 100K rate to verify the waveform? I am not sure if it is the correct parameter if I set it myself

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danielmartynek
NXP TechSupport
NXP TechSupport

Hello @jianqun,

For example this configuration should work:

danielmartynek_0-1669377680753.png

 

Regards,

Daniel

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