I want to use MAX7219 (datasheet) to control bunch of RGB LEDs. With common anode LEDs I should be able to use up to 16 3-color bulbs in following configuration:
There would be probably needed a resistor to protect the pins DIG 6 and DIG 7.
Now the RGB LED has drop voltage 3.2V on green/blue and 2.0V for the red color at 20mA. This would result in noticeable brightness difference of the LEDs. Is it possible to add 60Ω resistor to each red rail to fix the brightness of red color? The resistor is calculated from the voltage difference (3.2V-2.0V=1.2V) and driving current of 20mA. Given that only one LED is on at each time, this should be enough.
My goal is to control at least 16 RGB LED, in such way that I can control color of each bulb.