building matrix using 3w LED's

I want to look to build a large 8x8 matrix using single colour 3w leds. The leds will be 3w 3.4v forward voltage and 700ma.

i want to be able to dim them and get them turn on independently.

Can you charlieplex and PWM? Trying to do this as cheap as possible. i have limited electronics experience so if anyone has any guides that i could scale up that would be great.

I have an arduino mega and uno which i could use. If anyone also has tried the new shields like Adafruit 16-Channel 12-bit PWM/Servo Driver - I2C interface - PCA9685

PCA9685: Each LED output can be off or on (no PWM control), or set at its individual PWM controller value. The LED output driver is programmed to be either open-drain with a 25 mA current sink capability at 5 V or totem pole with a 25 mA sink, 10 mA source capability at 5 V.

So that’s not going to directly operate 3W LEDs.
How many levels of dimming do you want?
One option might be string of 64 WS2801 drivers with external transistors for controlling the LEDs.

Should be applicable with WS28xx series parts too.

WS2801.pdf (423 KB)

WS2803-preliminary-En.pdf (437 KB)