I’m currently doing my Diploma Thesis in Physics. Subject is an automated fiber coupler. Some mirrors are adjusted via piezos. To control everything I’m using an ADuC7026. Using an evalution board with an ADuC7020 everything works fine. But putting the ADuc7026 on a circuit board which I designed results in very strange behaviour.
Mainly the Chip will not communicate with the computer via UART. On receiving a backspace it should answer with “ADuC7026 etc.”. Right now it answers mainly with gibberish. From the look of the signal the core clock is not stable. Looking at the clock signal from the xclko one can see the amplitude of the clocksignal fluctuating, but only when the serial download button is pressed (p0.0 pulled to ground via 1k resistor).
Does anybody have any ideas what to check ?
The fluctuations of the clock change when placing the board nearer to the top of a metal table.