10 years, 4 months ago.

FRDM K64F SPI clock pin strange behavior

Hello. Few days ago i asked a question about K64F and Nokia LCD 5110. (http://mbed.org/questions/4296/FRDM-K64F-LCD-5110/)

Now i found the problem and it looks very strange for me.

When FRDM SPI clock pin (PTD1) is connected to LCD's clock input simply via wire then clock signal is not generated (always low). But if you touch this clock chain in any point by some metallic object (e. g. scope probe or screwdriver) or add to pin some load or pull-down then SPI clock will be generated and all working.

Why it like that and how to solve this problem?

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