Hi,

I have connected two 74HC164 shift out registers on a PIC 16F628.

I am able to control which bit I want active within the MCU, depending on a bank of input buttons.

When the shifting out process occurs, the proper LED turns on, but all the other LEDs lower than that active LED blink at a very weak intensity as I push the button.

They do not remain on, only blink faintly along with the press of the button. My solution was to add a circuit which I turn OFF the LEDs, perform the shift out process, and then turn the LEDs back ON.

It will remove the blink, but my solution is not very efficient. Does anyone have any idea what causes this 'blink' during shifting out and hopefully how to stop it?

Steve, my idea of adding a 22K resistor at the end of the LEDs worked on the breadboard, but does not work once I migrated to perf-board...? I'm still checking why, but that does not explain why I have that blink in the 1st place.

Robert