Hi Guys,
This is my first post on this forum.
I have a control board decommisioned from an Elnur starage heater. It has an Atmega32A AU 44 pin TQFP package. It also has 4 opto isolated triac outputs each capable of switching 16A at 230VAC. It has a 4 digit multiplexed led display and four buttons on the display board. The buttons share pins also connected to 4 of the display segments switching to ground via a 4k7 resistor.
My question is, how do I program the display and the buttons on the same pin? It is not possible to re-wire the buttons or display without making a new pcb!
Attached is a pdf schematic of the relavent circuit!
Many thanks in advance for any advice.
Seamus
Schematic.pdf (41.2 KB)