STV0681 datasheet(26/44 Pages) STMICROELECTRONICS

26 / 44 page

STV0681 Hardware Interfaces

STV0681

26/44

ADCS 7283313C

4.9

Flashgun hardware interface

STV0681 will revert to flashgun exposure when it detects GPIO2 is high. Ideally the hardware

should combine the two factors of (a) user intention (e.g. user switches on flashgun) and (b) charge

sensing (i.e. flash is charged up and ready to fire).

These two factors (a) and (b) are independent, since there may be a delay of several seconds

between switching on the flashgun charger, and the flashgun being able to fire. To revert to flashgun

exposure before the flashgun is completely charged up would cause very bad pictures to be taken

in low light conditions because there is no “low light” threshold when flashgun exposure is enabled,

since the camera expects a flash to fire. A suggested flashgun hardware interface is given in the

flashgun application note AN1312.

When flashgun exposure is enabled and the shutter button is pressed, a picture is taken and the

flash trigger pin GPIO7 is pulsed low at the correct point in time so that all lines of the CMOS imager

are exposed.

4.10

IR filter

An Infra-Red Blocking Filter is required to achieve correct colour response. The exact specification

for the IR filter characteristics are given in the reference design manual.

STV0681 bảng dữ liệu(PDF) 26 Page - STMicroelectronics