MT9V112 Datasheet, PDF (30/58 Pages) Micron Technology – SOC VGA DIGITAL IMAGE SENSOR

PRELIMINARY
MT9V112
SOC VGA DIGITAL IMAGE SENSOR
Table 10: Camera Control Register Description (continued)
R103:2—0x267 – Auto Exposure Digital Gain Limits (R/W)
Default
0x4010
Description This register specifies the upper limits of the digital gains used by the auto exposure algorithm. The values
programmed to this register are 16 times the absolute gain values. The value of 16 represents the gain 1.0.
Bits 15:8
Maximum limit on post-lens correction digital gain.
Bits 7:0
Maximum limit on pre-lens correction digital gain.
R156:2—0x29C – Auto Exposure Speed and Sensitivity Control—Context B (R/W)
Default
0xDF20
Description This register specifies the speed and sensitivity to auto exposure changes in context B.
Bit 15
Reserved.
Bit 14
Reserved.
Bits 13:12 Reserved.
Bit 11
Reserved.
Bit 10
Reserved.
Bit 9
Reserved.
Bits 8:6
Factor of reduction of the difference between current luma and target luma. In one adjustment, auto
exposure advances from current luma to target as follows:
“000”—1/4 way going down, 1/8 going up.
“001”—1/4 way in both directions.
“010”—1/2 way in both directions.
“011”—1/2 way going down, 1/4 going up.
“100”—All the way in both directions (fast adaptation!).
“101”—3/4 way in both directions.
“110”—7/8 way in both directions.
“111”—Reserved. Currently the same as “100.”
Bit 5
Reserved.
Bits 4:3
Auto exposure luma is updated every N frames, where N is given by this field.
Bits 2:0
Hysteresis control via time-averaged smoothing of luma data. Luma measurements for auto exposure are
time-averaged as follows:
“000”—Auto exposure luma = current luma.
“001”—Auto exposure luma = 1/2 current luma + 1/2 buffered value.
“010”—Auto exposure luma = 1/4 current luma + 3/4 buffered value.
“011”—Auto exposure luma = 1/8 current luma + 7/8 buffered value.
“100”—Auto exposure luma = 1/16 current luma + 15/16 buffered value.
“101”—Auto exposure luma = 1/32 current luma + 31/32 buffered value.
“110”—Auto exposure luma = 1/64 current luma + 63/64 buffered value.
“111”—Auto exposure luma = 1/128 current luma + 127/128 buffered value.
R180:2 – Reserved
R200:2—0x2C8 – Global Context Control (R/W)
Default
0x0000
Description
Defines sensor and colorpipe context for current frame. Context A is typically used to define preview or
viewfinder mode, while context B is typically used for snapshots. The bits of this register directly control the
respective functions, so care must be taken when writing to this register if a bad frame is to be avoided
during the context switch.
Bit 15
Controls assertion of sensor restart on update of global context control register. This helps ensure that the
very next frame is generated with the new context (a problem with regard to exposure due to the rolling
shutter). This bit is automatically cleared once the restart has occurred.
0: Do not restart sensor.
1: Restart sensor.
09005aef8154a39d/09005aef8175e6cc
MT9V112_2.fm- Rev. A 1/05 EN
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