AD9927BBCZ datasheet(58/100 Pages) AD

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AD9927

Rev. 0 | Page 58 of 100

FIELD COUNTERS

The AD9927 contains three field counters (primary, secondary,

and mode). When these counters are active, they increment

with each VD cycle. The mode counter is the field counter used

with the mode register to control the vertical timing signals,

which was discussed in the

MODE Registers section. The primary and secondary counters

are more flexible and are generally used for shuttering signal

applications. Both the primary and secondary counters have

several modes of operation that are dictated by Address 0x70,

including

•

Normal (single count)

•

RapidShot (repeating count)

•

ShotDelay (delayed count)

•

ShotDelay with RapidShot

•

Manual exposure

•

Manual readout

•

Force to idle

The primary counter regulates the expose and read actions by

regulating the SUBCK and VSG signals. In addition, if the

RapidShot feature is used with the primary counter, the SUBCK

and VSG masking automatically repeats as necessary for

multiple expose/read cycles. The secondary counter has no

effect on the SUBCK or VSG signal. Both counters can be used

to regulate the general-purpose signals described in the

General-Purpose Outputs (GPOs) section.

Table 41. Primary/Secondary Field Counter Registers (Address 0x70, Address 0x71, and Address 0x72)

Length

Description

PRIMARY_ACTION

0: idle, no counter action. GPO signals can still be controlled using polarity or GP_PROTOCOL = 1.

SECOND_ACTION

1: activate counter. Single cycle of counter from 1 to counter maximum value, and then returns to idle

state.

2: RapidShot. After reaching maximum counter value, counter wraps and repeats until reset.

3: ShotTimer: Active single cycle of counter after added delay of N fields (use the corresponding DELAY

4: ShotTimer with RapidShot. Same as 2, with added delay of N fields between each repetition.

5: manual exposure. Primary counter stays in exposure until manual readout or reset to idle.

This mode keeps the SUBCK and VSG pulses masked indefinitely.

6: manual readout. Primary counter switches to readout (VSG pulses becomes active).

7: force to idle.

PRIMARY_MAX

13b

Primary counter maximum value.

SECOND_MAX

12b

Secondary counter maximum value.

VDHD_MASK

Mask VD/HD during counter operation.

PRIMARY_DELAY

13b

ShotTimer. Number of fields to delay before the next primary count (exposure) starts. If using ShotTimer

with RapidShot, delay value is used between each repeat.

PRIMARY_SKIP

When using ShotTimer with RapidShot, use primary delay value only before first count (exposure).

SECOND_DELAY

13b

ShotTimer. Number of fields to delay before the next secondary count starts. If using ShotTimer with

RapidShot, delay value is used between each repeat.

SECOND_SKIP

When using ShotTimer with RapidShot, use secondary delay value only before first count.

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