MISO crosstalk

A project log for PIXI Analog Shield

An Arduino Shield using the Maxim MAX11300 for 20 Programmable Mixed-Signal I/O with 12-Bit ADC, 12-Bit DAC, Analog Switches, and GPIO

magicwolfiMagicWolfi 11/23/2015 at 00:080 Comments

I am currently testdriving a Tek scope and found one issue on the board that was undetected so far.

The MISO signal picks up some cross-talk from the parallel SCK lock line during the cycle that writes the register address to the MAX11300 chip. This is how it looks on the scope.

The amplitude of the signal is to low to cause any glitches, but a different board with a different flavor of Arduino might look differently.

A pull-down resistor should take care of this issue and finally there is a good reason for the next revision.