How to power multiple LEDs with a microcontroller I currently have a "tiny" setup and want to put a few (~20-30) 0402 LEDs on a 1:87 scale car. My current setup is an ATtiny85 USB Mini Dev Board powered by a 90mAh 3.7V LiPo battery which is connected to a TP4056 5V micro USB Lipo battery charger:

To my bitter disappointment one cannot connect the leds in series. I've read about charlieplexing which was a little mind boggling for me to comprehend.

I was going to break down the leds and pins as follows:


P0 - headlights (2x white 0402 LEDs) +  tail lights (2x red 0402 LEDs) - in series - in parrallel
P1 - blinkers (4x amber 0402 LEDs) - in series - in parrallel
P2 - siren (12x amber 0402 LEDs) - in series - in parrallel
P3 - beacon (2x blue 0402 LEDs) - in series - in parrallel
P4 - beacon (2x blue 0402 LEDs) - in series - in parrallel
P5 - beacon (2x blue 0402 LEDs) - in series - in parrallel


Question:


With space being limited inside the model car how would I be able to
drive 20-30 LEDs with the above set up? 
I am in doubt that the models in the video use charlieplexing and use a similar microcontroller, how would they be doing this?
Would it be better for me use something like a Pro Micro ATmega32U4 5V 16MHz and spread the LEDs across the 16 pins (ie 2 LEDs per pin = total of 32 LEDs)?
I see no reason why you would not be able to light 30 LEDs.
ATtiny85 only has 5 pins for use (unless you want to use the reset pin as well in which case hell will cover you). So with charlieplexing you are going to be able to address 20 endpoints. (where each endpoint might consist of multiple LEDs)
But beware. You CAN address 20 endpoints but you CANNOT light every combination simultaneouly. You will have to work out if there is a constellation that allows you to light all lights you want in the same time or you will have to use one of the timers to toggle between different lights. I don't know how well it works thou.
I have managed to use a timer on an 8MHz device to drive 4 LEDs at 400Hz directly without charlieplexing and not using PWM. So I assume it will be possible but might be flickering.
It would definitively be easier. I always recommend to stick to things that are well known and widely used. That would fit your ATmega32U4.


Make sure you layout your LEDs and think how you want to address them and if it makes sense to join multiple LEDs to one pin and toggle them at once.