MT9M034_16 Datasheet, PDF (33/53 Pages) ON Semiconductor – 1/3-Inch CMOS Digital Image Sensor

MT9M034: 1/3-Inch CMOS Digital Image Sensor
Features
Column correction can be enabled/disabled via R0x30D4[15]. Additionally, the number
of rows used for this offset coefficient measurement is set in R0x30D4[3:0]. By default
this register is set to 0x7, which means that 8 rows are used. This is the recommended
value. Other control features regarding column correction can be viewed in the
MT9M034 Register reference. Any changes to column correction settings need to be
done when the sensor streaming is disabled and the appropriate triggering sequence
must be followed as described below.
Column Correction Triggering
Column correction requires a special procedure to trigger depending on which state the
sensor is in.
Column Triggering on Startup
When streaming the sensor for the first time after powerup, a special sequence needs to
be followed to make sure that the column correction coefficients are internally calcu-
lated properly.
1. Follow proper power up sequence for power supplies and clocks.
2. Apply sequencer settings if needed (Linear or HDR mode).
3. Apply frame timing and PLL settings as required by application.
4. Set analog gain to 1x and low conversion gain (R0x30B0=0x1300)
5. Enable column correction and settings (R0x30D4=0xE007).
6. Disable auto re-trigger for change in conversion gain or col_gain, and enable column
correction always (R0x30BA = 0x0008).
7. Enable streaming (R0x301A[2]=1)or drive the TRIGGER pin HIGH.
8. Wait 9 frames to settle (First frame after coming up from standby is internally column
correction disabled).
9. Disable streaming (R0x301A[2]=0).
After this, the sensor has calculated the proper column correction coefficients and the
sensor is ready for streaming. Any other settings (including gain, integration time and
conversion gain etc.) can be done afterwards without affecting column correction.
Column Correction Retriggering Due to Mode Change
Since column offsets is sensitive to changes in the analog signal path, such changes
require column correction circuitry to be retriggered for the new path. Examples of such
mode changes include: horizontal mirror, vertical mirror, changes to column correction
settings.
When such changes take place, the following sequence needs to take place:
1. Disable streaming (R0x301A[2]=0) or drive the TRIGGER pin LOW.
2. Enable streaming (R0x301A[2]=1) or drive the TRIGGER pin HIGH.
3. Wait 9 frames to settle.
Note:
The above steps are not needed if the sensor is being reset (soft or hard reset) upon
the mode change.
Defective Pixel Correction
Defective Pixel Correction is intended to compensate for defective pixels by replacing
their value with a value based on the surrounding pixels, making the defect less notice-
able to the human eye. The defect pixel correction feature supports up to 200 defects.
MT9M034/D Rev. 8, 2/16 EN
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