STV2050A datasheet(59/83 Pages) STMICROELECTRONICS

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STV2050A - OPTICAL LOOP

12 OPTICAL LOOP

12.1 PRINCIPAL OF OPERATION

Figure 33. Optical Loop

The STV2050A can deliver a dedicated video pattern known as an “auto-alignment pattern”.

This pattern is rectangular-shaped, and its width, height and brightness are programmable.

Refer to Section 7.6 "Auto-alignment Pattern" on page 40.

The presence or absence of this pattern can be detected by optical sensors; for example, by

a camera in the production line, or photo detector diodes placed around the Projection screen.

The STV2050A can read the status of the sensors within a programmable time limit. The re-

sults are made available in the E5 register, allowing the MCU to run a routine for making the

necessary corrections.

Two pins are dedicated to the optical loop:

– The OPPT pin is a port normally used as an output, and can deliver a logical electrical signal

with a programmable time limit.

– The OPTI pin is an input port for logical 0 or 1 levels. This port is sampled by the STV2050A

to indicate the status of the sensor.

12.2 OPTT SENSOR PORT CONTROL

The OPTT sensor port can be programmed as an input or as an output by the ODS in the E5

ODS

0 = OPTT is an input

1 = OPTT is an output

OPTT

RGB

OPTI

I²C

µP

sensor

H/V

grid

timing

STV 2050D

Offset

Static

Gain

Dynamic

STV2050A

STV2050A Datasheet(PDF) 59 Page - STMicroelectronics