I have 200 5V LEDs, which each use about 5mW. I would like to be able to control all of them individually using a Raspberry Pi. I understand that I would need to use an external power supply (which I have), but I have been unable to work out what kind of components I need to use. Demultiplexers and shift registers both seem to be options, but all the advice I have found refers to arranging LEDs in a matrix and then scanning through it, which is not an option in my case.
I would ideally like to be able to vary the brightness of these LEDs, either by varying the voltage or by PWM (preferably PWM).
I would be extremely grateful for any advice.