Datasheet
Table Of Contents
- applications
- features
- key specifications
- table of contents
- list of figures
- list of tables
- 1 signal descriptions
- 2 system level description
- 3 block level description
- 4 image sensor core digital functions
- 4.1 mirror and flip
- 4.2 image windowing
- 4.3 test pattern
- 4.4 50/60Hz detection
- 4.5 AEC and AGC algorithms
- 4.6 AEC/AGC steps
- 4.7 black level calibration (BLC)
- 4.8 strobe flash and frame exposure
- 4.9 xenon flash control
- 4.10 frame exposure (FREX) mode
- 4.11 FREX strobe flash control
- 4.12 one-time programmable (OTP) memory
- 5 image sensor processor digital functions
- 6 image sensor output interface digital functions
- 7 register tables
- table 7-1 system control registers (sheet 1 of 5)
- table 7-2 SCCB registers (sheet 1 of 2)
- table 7-3 group hold control registers
- table 7-4 AEC/AGC 1 registers
- table 7-5 system timing registers (sheet 1 of 3)
- table 7-6 AEC/AGC 2 registers (sheet 1 of 3)
- table 7-7 STROBE/frame exposure control registers (sheet 1 of 2)
- table 7-8 50/60 HZ DETECTION registers
- table 7-9 OTP control registers (sheet 1 of 2)
- table 7-10 BLC registers (sheet 1 of 3)
- table 7-11 frame control registers
- table 7-12 DVP registers (sheet 1 of 2)
- table 7-13 MIPI top registers (sheet 1 of 11)
- table 7-14 ISPFC registers
- table 7-15 ISP TOP control registers (sheet 1 of 6)
- table 7-16 AWB registers (sheet 1 of 3)
- table 7-17 average registers (sheet 1 of 2)
- table 7-18 DPC registers
- table 7-19 LENC registers (sheet 1 of 4)
- table 7-20 cluster DPC registers (sheet 1 of 2)
- table 7-21 windows registers
- table 7-22 AEC/AGC 3 registers
- 8 operating specifications
- 9 mechanical specifications
- 10 optical specifications
- revision history
Confidential for truly Only
color CMOS QSXGA (5 megapixel) image sensor with OmniBSI™ technology
OV5647
proprietary to OmniVision Technologies PRELIMINARY SPECIFICATION version 1.0
4.5.2 average-based algorithm
The average-based AEC controls image luminance using registers WPT (0x3A0F), BPT (0x3A10), WPT2 (0x3A1B), and
BPT2 (0x3A1E). In average-based mode, the value of register WPT (0x3A0F) indicates the high threshold value for
image change from unstable to stable state, and the value of register BPT (0x3A10) indicates the low threshold value for
image change from unstable to stable state. The value of register WPT2 (0x3A1B) indicates the high threshold value for
image change from stable state to unstable state and the value of register BPT2 (0x3A1E) indicates the low threshold
value for image change from stable state to unstable state. When the target image luminance average value AVG
(0x5693) is within the range specified by registers
WPT2 (0x3A1B) and BPT2 (0x3A1E), the AEC keeps the image
exposure and gain. When register AVG (0x5693) is greater than the value in register WPT2 (0x3A1B), the AEC will
decrease the image exposure and gain until it falls into the range of {0x3A10, 0x3A0F}. When register AVG (0x5693) is
less than the value in register
BPT2 (0x3A1E), the AEC will increase the image exposure and gain until it falls into the
range of {0x3A10, 0x3A0F}. Accordingly, the value in register WPT (0x3A0F) should be greater than the value in register
BPT (0x3A10). The value of register WPT2 should be no less than the value of register WPT(0x3A0F), and the value of
register BPT2 (0x3A1E) should be no greater than the value of BPT (0x3A10).
The AEC function supports both manual and auto speed selections in order to bring the image exposure into the range
set by the values in registers
WPT (0x3A0F) and BPT (0x3A10). For manual speed mode, the step is fixed and supports
both normal and fast modes. AEC set to normal mode will allow for the slowest step increment or decrement in the image
exposure to maintain the specified range. AEC set to fast mode will provide for an approximate ten-step increment or
decrement in the image exposure to maintain the specified range. For auto speed mode, the step will automatically be
adjusted according to the difference between the target and present values. The auto ratio of steps can be set by register
bits AEC CTRL05[4:0] (0x3A05).
Register HIGH VPT (0x3A11) and register LOW VPT (0x3A1F) controls the fast AEC range in manual speed mode. If
the target image AVG (0x5693) is greater than HIGH VPT (0x3A11), AEC will decrease by half. If register AVG (0x5693)
is less than LOW VPT (0x3A1F), AEC will double, as shown in
figure 4-7. These registers have no effect in auto speed
mode.
figure 4-7 desired convergence
control zone stable operating region
desired convergence
5647_DS_4_7
0x3A1F
0x3A11