You are saying that writing the value 0x46 to address 0xC022000C triggers the camera's electronic flash ?
Yes (if flash's capacitor is full and battery not low voltage), and the same situation is for sx210 and sd3500, but addresses may be different, because I don't explore deeply that cameras, just used blinker (0xC0220000-0xC02200FF), and flash triggered.
But flash triggers just once, I don't know why, because if &(0xC022000C)==0x46 flash must triggers when capacitor recharge process completed, but recharge time pass and nothing happens. I'll make some experiments with flash tomorrow, and report any results