AR0833 Datasheet, PDF (24/64 Pages) ON Semiconductor – 8 Mp CMOS Digital Image Sensor

AR0833: 1/3.2-Inch 8 Mp CMOS Digital Image Sensor
Registers
Using grouped_parameter_hold
Register grouped_parameter_hold (R0x301A[15]) can be used to inhibit transfers from
the pending to the live registers. When the AR0833 is in streaming mode, this register
should be written to “1” before making changes to any group of registers where a set of
changes is required to take effect simultaneously. When this register is written to “0,” all
transfers from pending to live registers take place on the next frame start.
An example of the consequences of failing to set this bit follows:
An external auto exposure algorithm might want to change both gain and integration
time between two frames. If the next frame starts between these operations, it will
have the new gain, but not the new integration time, which would return a frame with
the wrong brightness that might lead to a feedback loop with the AE algorithm result-
ing in flickering.
Bad Frames
A bad frame is a frame where all rows do not have the same integration time or where
offsets to the pixel values have changed during the frame.
Many changes to the sensor register settings can cause a bad frame. For example, when
line_length_pck (R0x300C) is changed, the new register value does not affect sensor
behavior until the next frame start. However, the frame that would be read out at that
frame start will have been integrated using the old row width, so reading it out using the
new row width would result in a frame with an incorrect integration time.
By default, bad frames are masked. If the masked bad frame option is enabled, both LV
and FV are inhibited for these frames so that the vertical blanking time between frames
is extended by the frame time.
In the register tables, the “Bad Frame” column shows where changing a register or
register field will cause a bad frame. This notation is used:
N—No. Changing the register value will not produce a bad frame.
Y—Yes. Changing the register value might produce a bad frame.
YM—Yes; but the bad frame will be masked out when mask_corrupted_frames
(R0x301A[9]) is set to “1.”
Changes to Integration Time
If the integration time is changed while FV is asserted for frame n, the first frame output
using the new integration time is frame (n + 2). The sequence is as follows:
1. During frame n, the new integration time is held in the pending register.
2. At the start of frame (n + 1), the new integration time is transferred to the live register.
Integration for each row of frame (n + 1) has been completed using the old integration
time.
3. The earliest time that a row can start integrating using the new integration time is
immediately after that row has been read for frame (n + 1). The actual time that rows
start integrating using the new integration time is dependent upon the new value of
the integration time.
4. When frame (n + 2) is read out, it will have been integrated using the new integration
time.
If the integration time is changed on successive frames, each value written will be
applied for a single frame; the latency between writing a value and it affecting the frame
readout remains at two frames.
AR0833_DS Rev. H Pub. 4/15 EN
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