XIIMUS 4K CL User Manual. Model: 4096CT. Version 1.4
3.7.
Exposure control mode (address 204)
The Exposure Control function can be applied individually to each CCD. As default, one
common input signal (ExpCtrl_R) drives all the three CCDs. Alternatively each CCD can have
its dedicated input signal for the Exposure Control.
Address for modifying the Exposure Control function:
Function decimal
hexadecimal binary
Exposure Control
Mode
204 CC
1100
1100
This function is used like the setting of the gains (see above). The data byte consists of eight
bits, which are labelled as follows (MSB first):
S R1 R0 G1 G0 B1 B0 X
Bit S selects the source for the Exposure Control functions:
0 = common ExpCtrl signal (default)
1 = individual ExpCtrl signals
The next 6 bits are used as pairs for each colour channel (see table below). As default, these
are all zeros, and there is no need to change them. They can, though, be used for testing or
debugging the system.
In the normal state, Exposure Controls are driven directly from the input pins of the camera
(as set by the bit S). The Exposure Control can be set to be always inactive (respective
channel is never reset by the Exposure Control) or to be always active (pixels are reset all
the time by the Exposure Control - this results to a dark output value for the selected
channel).
The third choice is a test mode, where the pixels are reset until the end of the LineValid
signal. This is a constant time. Thus the amount of exposure will depend on the line rate only
(see Timing Diagrams for details).
R1 R0
Function
0
0
normal operation, default, the source is defined by the bit 'S'
0
1
always inactive, full exposure, independent of the bit 'S'
1
0
always active, dark, independent of the bit 'S'
1
1
active (pixels reset) during line transfer, independent of the bit 'S'
The same applies to pairs of G1 and G0 as well as for B1 and B0. The bit X can be either '1'
or '0' ("don't care").
Examples:
Default value is 00. The ExpCtrl_R input pins drive all the CCDs.
To return to this state send a 2-byte set 204 (decimal) and 0 (or 204 and 1).
Set all the channels to dark by sending 204 followed by 84.
Only red channel at full time exposure: 204 followed by 52.
Only green channel at full time exposure: 204 followed by 76.
Only blue channel at full time exposure: 204 followed by 82.
Exposure control function not in use: send 204 followed by 42.
© TVI Vision, 14 July 2006 page 42 ( 56 )