This branch v0.69k_J16J17 is a copy of v0.69k and has support for switchting J16 (POTI2 in Koptertool) and J17 (POTI3 in Koptertool) on the FC board: DIFFERENCES: main.c -> line 119: DDRC changed from 0x81 (128+1) to 0x8D (128+8+4+1) to make PC2 and PC3 outputs main.h -> lines 22-25: defined references for J16 (=PortC2 output2) and J17 (=PortC output3): #define J16_ON PORTC |= 0x04 #define J16_OFF PORTC &=~0x04 #define J17_ON PORTC |= 0x08 #define J17_OFF PORTC &=~0x08 fc.c -> line 634-637: added switching behaviour based on POTI2 and POTI3 if POTI2 > 75, output PC2 (J16) will switch to ground = ON if POTI2 <= 75, output PC2 (J16) will remain open collector = OFF if POTI3 > 75, output PC3 (J17) will switch to ground = ON if POTI3 <= 75, output PC3 (J17) will remain open collector = OFF NOTE on J16/J17 usage: - use an optocoupler to switch external devices like camera's - you can drive a LED straight on J16 or J17 (cathode on J16/J17, anode on +5V), but do not exceed 100mA (otherwise 7805 stabiliser gets too hot). T1 and T2 can handle each max. 500mA but mind the 7805 on the FC - if you want to drive higher currents (for external high power LED's): use an extra FET or a BD transistor (eg: BD138 PNP) via the battery supply (not the +5V from the FC) Good Luck! Harrie - MosaKopter