Here is an application note from Microchip describing how a PIC12HV615 MCU can be used to implement a digital current control loop for power LEDs:
This document describes a power LED driver solution using the PIC12HV615 microcontroller (MCU). The PIC12HV615 is an 8-pin MCU with many integrated analog features. The LED driver circuit is a buck (stepdown) solution and the circuit presented here can operate from most any input voltage source as long as it exceeds the forward voltage of the LEDs to be driven.