AD9927 Analog Devices, AD9927 Datasheet - Page 58

• Manufacturer Part Number: AD9927
• Description: 14-Bit CCD Signal Processor
• Manufacturer: Analog Devices

AD9927
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
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Table 41. Primary/Secondary Field Counter Registers (Address 0x70, Address 0x71, and Address 0x72)
Register
PRIMARY_ACTION
SECOND_ACTION
PRIMARY_MAX
SECOND_MAX
VDHD_MASK
PRIMARY_DELAY
PRIMARY_SKIP
SECOND_DELAY
SECOND_SKIP
Normal (single count)
RapidShot (repeating count)
Length
3b
3b
13b
12b
3b
13b
1b
13b
1b
Description
0: idle, no counter action. GPO signals can still be controlled using polarity or GP_PROTOCOL = 1.
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
register).
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 counter maximum value.
Secondary counter maximum value.
Mask VD/HD during counter operation.
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.
When using ShotTimer with RapidShot, use primary delay value only before first count (exposure).
ShotTimer. Number of fields to delay before the next secondary count starts. If using ShotTimer with
RapidShot, delay value is used between each repeat.
When using ShotTimer with RapidShot, use secondary delay value only before first count.
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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.
ShotDelay (delayed count)
ShotDelay with RapidShot
Manual exposure
Manual readout
Force to idle