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Messages - doum

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Character LCDs / NHD-C0220BiZ-FSW-FBW-3V3M I2C SDA glitch and freeze.
« on: September 08, 2016, 08:33:46 AM »
Hi,

I have observed that the I2C bus freeze on my new design, and i searched the cause and found this. During my display initialization sometime the I2C stop working with the SDA line stuck to GND. If i reset my display the SDA return to 1 and i can configure it again.

I observed a glitch on the SDA line, witch cause a STOP condition on the I2C bus and halt my controller.

This glitch always happen at the end of the 0x6C command, Follower Control.

I attached a oscilloscope capture of this glitch. The SDA line is the yellow trace. You can see the glitch witch cause a stop condition to the I2C controller. I also saw this glitch on the C1+ C1- pins.

I changed my pull-up to 10k (from 4.7k) and it's much better. The glitch is still there but at least i can use my design.

Capacitor is 1uf 50v ceramic.

Any idea?

Thank you.


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