MT9P031I12STM-ES Aptina LLC, MT9P031I12STM-ES Datasheet - Page 43

• Manufacturer Part Number: MT9P031I12STM-ES
• Manufacturer: Aptina LLC

Specifications of MT9P031I12STM-ES

• Lead Free Status / RoHS Status: Supplier Unconfirmed

Synchronizing Register Writes to Frame Boundaries
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MT9P031_DS - Rev. E 7/10 EN
usually active during the readout of the previous frame. Therefore, any register changes
that could affect the row time or the set of rows sampled causes the shutter pointer to
start over at the beginning of the next frame.
By default, the following register fields cause a "bubble" in the output rate (that is, the
vertical blank increases for one frame) if they are written in continuous mode, even if the
new value would not change the resulting frame rate:
• Row_Start
• Row_Size
• Column_Size
• Horizontal_Blank
• Vertical_Blank
• Shutter_Delay
• Mirror_Row
• Row_Bin
• Row_Skip
• Column_Skip
The size of this bubble is (SW ×
settings.
The Shutter_Width_Lower and Shutter_Width_Upper fields may be written without
causing a bubble in the output rate under certain circumstances. Because the shutter
sequence for the next frame often is active during the output of the current frame, this
would not be possible without special provisions in the hardware. Writes to these regis-
ters take effect two frames after the frame they are written, which allows the shutter
width to increase without interrupting the output or producing a corrupt frame (as long
as the change in shutter width does not affect the frame time).
Changes to most register fields that affect the size or brightness of an image take effect
on the frame after the one during which they are written. These fields are noted as
“synchronized to frame boundaries” in Table 12: Register List and Default Values on
page 20. To ensure that a register update takes effect on the next frame, the write opera-
tion must be completed after the leading edge of FV and before the trailing edge of FV.
As a special case, in Snapshot modes (see “Operating Modes” on page 46), register writes
that occur after FV but before the next trigger will take effect immediately on the next
frame, as if there had been a Restart. However, if the trigger for the next frame in ERS
Snapshot mode occurs during FV, register writes take effect as with continuous mode.
Additional control over the timing of register updates can be achieved by using
synchronize_changes. If this bit is set, writes to certain register fields that affect the
brightness of the output image do not take effect immediately. Instead, the new value is
remembered internally. When synchronize_changes is cleared, all the updates simulta-
neously take effect on the next frame (as if they had all been written the instant
synchronize_changes was cleared). Register fields affected by this bit are identified in
Table 13: Register Description on page 25.
Fields not identified as being frame-synchronized or affected by synchronize_changes
are updated immediately after the register write is completed. The effect of these regis-
ters on the next frame can be difficult to predict if they affect the shutter pointer.
43
t
ROW), calculating the row time according to the new
MT9P031: 1/2.5-Inch 5Mp Digital Image Sensor
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©2005 Aptina Imaging Corporation. All rights reserved.
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