Glitches, and how to get rid of them

A project log for Digi:Arka

Dirt-cheap Vaus paddle clone for MSX - Now supports Standard Paddles too.

danjovicdanjovic 04/02/2020 at 00:020 Comments

First tests have been performed with the aid of an arduino to generate the signals and evertything went fine.

Today I have connected the circuit on a breadboard and ran TESTVAUS program but the results reported were not good.

I have connected a logic analyzer and observed some noise on the PULSE line (pin 8).

The glitches appear mostly ramdom along the readings and some times the same reading counted three glitches, all of them close to an edge of the clock signal. The width of such beasts is around 40ns.

Repated the same tests now using the ARKANOID game and observed the same glitches.

I have considered some tricks in software to ignore the glitches but the simplest method is implemented in hardware: A 470pf capacitor connected between pin 8 (pulse) and ground.

The results were immediate both on TESTVAUS

And during game.