AD9927 Analog Devices, AD9927 Datasheet - Page 59

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

GENERAL-PURPOSE OUTPUTS (GPO
The AD9927 provides programmable outputs to control a
mechanical shutter, strobe/flash, the CCD bias select signal, or
any other external component with general-purpose (GP)
signals. Eight GP signals, with up to four toggles each, are
available that can be programmed and assigned to special GPO
pins. These pins are bidirectional and allow visibility (as an
output) and external control (as an input) of HBLK, PBLK,
CLPOB, and OUTCONTROL. The registers introduced in this
section are described in Table 42.
GP Toggles
When configured as an output, each GPO1 to GPO8 output can
deliver a signal that is the result of programmable toggle
positions. The GP signals are independent and can be linked to
either a specific VD period or over a range of VD periods via
the primary or secondary field counters through the GP
protocol register (Address 0x73). As a result of their
associations with the field counters, the GP toggles inherit the
characteristics of the field counters, such as RapidShot and
ShotDelay. To use the GP toggles
1.
2.
3.
4.
Table 42. GPO Registers
Register
GP1_PROTOCOL
GP2_PROTOCOL
GP3_PROTOCOL
GP4_PROTOCOL
GP5_PROTOCOL
GP6_PROTOCOL
GP7_PROTOCOL
GP8_PROTOCOL
MANUAL_TRIG
GP<1:8>_POL
SEL_GP<1:8>
GPO_OUTPUT_EN
GP*_USE_LUT
LUT_FOR_GP12
LUT_FOR_GP34
Program the toggle positions (Address 0x7A to
Address 0xA9).
Program the protocol (Address 0x73).
Program the counter parameters (Address 0x71 to
Address 0x72).
Activate the counter (Address 0x70).
Length
3b
3b
3b
3b
3b
3b
3b
8b
8b
8b
8b
8b
8b
4b
4b
Range
0 to 7
0 to 7
0 to 7
0 to 7
0 to 7
0 to 7
0 to 7
0 to 7
Off/on
Low/high
Off/on
Off/on
Off/on
Logic setting
Logic setting
S
)
Description
0: idle.
1: no counter association, use MANUAL_TRIG bits to enable each GP signal.
2: link to primary counter.
3: link to secondary counter.
4: link to mode counter (from vertical timing generation).
5: primary repeat (allows GP signals to repeat with RapidShot).
6: secondary repeat (allows GP signals to repeat with RapidShot).
7: keep on.
Manual trigger for each GP signal, for use with Protocol 1.
Starting polarity for GP signals, only updated during PROTOCOL = 0.
1: select GP toggles visible at GPO1 to GPO8 when output is enabled (default);
0: select vertical signals visible at GPO4 to GPO8 when output is enabled.
1: enable GPO1 to GPO8 outputs (one bit per output);
0: disable GPO1 to GPO8 outputs, pins will be high-Z state (default).
Send GP signals through a programmable look-up table (LUT).
Desired logic to be realized on GP1 combined with GP2.
Desired logic to be realized on GP3 combined with GP4.
GPO4: SUBCK.
GPO5: XV21.
GPO6: XV22.
GPO7: XV23.
GPO8: XV24.
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For Protocol 1 (no counter association), skip Steps 3 and 4.
With these four steps, the GP signals can be programmed to
accomplish many common tasks. Careful protocol selection and
application of the field counters yields efficient results to allow
the GP signals smooth integration with concurrent operations.
Note that the SUBCK and VSG masks are linked to the primary
counter; however, if their parameters are 0, the GPO can use the
primary counter without expose/read activity.
The secondary counter is independent and can be used
simultaneously with the primary counter. Some applications
may require the use of both primary and secondary field
counters with different GPO protocols, start times, and
durations. Such operations are easily handled by the AD9927.
Several simple examples of GPO applications using only one
GPO and one field counter follow. These examples can be used
as building blocks for more complex GPO activity. In addition,
specific GPO signals can be passed through a 4-input LUT to
realize combinational logic between them. For example, GP1
and GP2 can be sent through an XOR look-up table, and the
result can be delivered on GP1, GP2, or both. Also, either GP1
or GP2 can deliver their original toggles.
AD9927