I'm trying to build a LED bargraph with 24 LEDs and an Attiny44.
I was thinking to multiplex the display as every 10ms, a group of 6 LED is selected with PORTB, and LED to be displayed are selected with PORTA (a kind of 4 colums x 6 lines matrix).
I used a BS170 to select 1 6 LED group among 4, as attiny cannot drive 6 LEDS with 1 PIN.
The issue is that all works well in simulation, but IRL only first 3 LEDS are set.
If I try with only 2 groups (so 12 LEDS), it works fine, I am thinking of an HW issue, but cannot figure out where I shall start to work.
Any idea guys?
For better understanding, schematic is attached.