AR0833 Datasheet, PDF (43/64 Pages) ON Semiconductor – 8 Mp CMOS Digital Image Sensor

AR0833: 1/3.2-Inch 8 Mp CMOS Digital Image Sensor
Integration Time for Interlaced HDR Readout
Scaler
Scaling reduces the size of the output image while maintaining the same field-of-view.
The input and output of the scaler is in Bayer format.
When compared to skipping, scaling is advantageous as it avoids aliasing. The scaling
factor, programmable in 1/16 steps, is used for horizontal and vertical scalers.
The AR0833 sensor is capable of horizontal scaling and full (horizontal and vertical)
scaling.
The scale factor is determined by:
• n, which is fixed at 16
• m, which is adjustable with register R0x0404
• Legal values for m are 16 through 96, giving the user the ability to scale from
1:1 (m=16) to 1:6 (m=96).
Frame Rate Control
The formulas for calculating the frame rate of the AR0833 are shown below.
The line length is programmed directly in pixel clock periods through register
line_length_pck. For a specific window size, the minimum line length can be found from
Equation 8:
minimum
line_length_pck
=


x---_---a---d---d---r---_---e--n---d---------x---_---a---d---d---r--_---s---t-a---r---t----+------1-
subsampling factor
+
min_line_blanking_pck_
(EQ 8)
Note that line_length_pck also needs to meet the minimum line length requirement set
in register min_line_length_pck. The row time can either be limited by the time it takes
to sample and reset the pixel array for each row, or by the time it takes to sample and
read out a row. Values for min_line_blanking_pck are provided in “Minimum Row Time”
on page 43.
The frame length is programmed directly in number of lines in the register
frame_line_length. For a specific window size, the minimum frame length can be found
in Equation 9:
minimum
frame_length_lines
=


y---_---a---d---d---r---_---e--n---d---------y---_---a---d---d---r--_---s---t-a---r---t----+------1-
subsampling factor
+
min_frame_blanking_lines_
(EQ 9)
The frame rate can be calculated from these variables and the pixel clock speed as
shown in Equation 10:
frame rate = -----------v---t--_---p---i--x--e---l--_---c---l-o---c---k---_---m----h---z----x----1-----x----1---0---6------------
line_length_pck_x frame_length_lines
(EQ 10)
If coarse_integration_time is set larger than frame_length_lines the frame size will be
expanded to coarse_integration_time + 1.
Minimum Row Time
Enough time must be given to the output FIFO so it can output all data at the set
frequency within one row time.
There are therefore two checks that must all be met when programming
line_length_pck:
AR0833_DS Rev. H Pub. 4/15 EN
43
©Semiconductor Components Industries, LLC, 2015.