CFAG12864 E Pin kills micro


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I have a CFAG12864-YYH-V and a CFAG12864-WGH-V display for development of a new product. One of these displays has killed the microcontroller pin that is connected directly to the E pin of the display. Since I thought at first it was bad code, then a bad display I wasn't able to verify which display was on the board when the micro was killed and will have to chase that issue seperately.

I replaced the micro and the exact same thing happened again. At this point I knew it wasn't a random chance occurance.

I have since added a current limiting resistor between the display and micro pin to protect the micro and it hasn't failed again.

Has anyone seen this before? I've used thousands of displays before and have never seen an input pin to a display blow a microcontroller's I/O pin.

This is a direct connection between the micro output pin to the displays E pin. The waveform looks clean on the scope and the rise / fall times plus the E cycle time are all well within the display specifications.

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