Din jittering

Testing/Troubleshooting
1

I build mb64 on gregs pcb and connect another 40 d.inputs (5x74165) based on DINX_4_v2 design. When I was testing I found that some buttons is scanned even if I press nothing  :o. Than I disconect the buttons and the same effect occured. Actualy just the same note was scaned. When I disconect extension the jittering was smaller but still was there  ???. Of course that din is ended by clamp to Vcc.

Please help me with solving this problem.

B.R. Sodaman

2

The random notes could be caused by an “unterminated”

DIN chain. So far as I remember greg’s layout doesn’t come with

the regired 10k pull-up resistor on the input of the last 74HC165

(Pin 10). It should help :slight_smile:

Best Regards, Thorsten.