FPGA to AVR (or cheap FPGA) comms

[tim minke]

I need to send over a 2 wire signal with addressable positioning for RGBW lighting 
FROM an FPGA to an AVR (or a cheap FPGA) for the purpose of flashing led lighting with MOSFETs. 

I want to be able to have up to 32 lights on a single "line" and have 10 "lines" from the main FPGA.

PWM is needed for 3 level dimming (open to other sugestions)