ADE3800XT datasheet(37/138 Pages) STMICROELECTRONICS

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ADE3800

4.7.2

Input Sync - Measurement

One set of (HSync, vsync) can be selected for measurement.

Software can request measurements in one of two ways:

● One shot – one time measurement

● Free Run – continuously running measurements.

The measurement block also compares the measured sync signals to programmable limits.

● Xclks per vsync different by more than +/- 2^(xclk_vtol_exp[3:0])

● Xclks per HSync different by more than +/- 2^(xclk_htol_exp[3:0])

● HSyncs per vsync different by more than +/- HSync_vtol[3:0]

● polarity.

Range check flags will be set when the measurements exceed the programmed tolerances. The

flags will be updated on the completion of each measurement in Free Run mode. The flags

maintain their state at the completion of a measurement while in One Shot mode. When a

measurement is started (asserting the Measurement Start bit) the range check flags are cleared.

There are timeout registers to detect the absence of sync signals.

The measurement block registers are grouped into four main categories:

● Timeouts & Tolerances

● Measurements (obtained by a one-shot or free-run mode of operation)

● Reference values

● Flags (indicators that measurements have timed out or measurements compared to reference

values exceed tolerances).

4.7.3

Fast Mute

The fast mute block continuously monitors one selected HSync signal and compares its period with

an independent reference value and tolerance. A fast mute flag is set as soon as the measured

period is outside the tolerance for more than 1, 2 or 3 times in a row.

The fastmute range check flag can be combined with other reference checking flags with a mask-or

function to make a sticky bit to mute the screen rapidly in the event of a mode change or dropped

signal.

ADE3800XT 数据表(PDF) 37 Page - STMicroelectronics