I have trouble with serial communication between FRDM K64F and LCD 5110.
When FRDM SPI clock pin (PTD1) is connected to LCD's clock input simply via wire then clock signal stay always low. But if you touch this clock chain in any point by some conductive object (e. g. scope probe or screwdriver) or add to pin some pull-down resistor and reset the board then SPI clock will be generated and LCD work fine.
other spi lines work without problems.
I also checked this LCD with another board and with same wiring everything works fine without any bugs.
Can anyone explain this behavior?