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MT9T111_DG - Rev. B 9/10 EN
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MT9T111: Developer Guide
JPEG Encoder
Preliminary
Spoof Oversize Error
The spoof oversize error only occurs in spoof mode running on the parallel output inter-
face (the MIPI/CCP interface does not have a spoof oversize error). This error occurs
when the spoof size, which is equal to spoof_width * spoof_height is not long enough to
hold the compressed JPEG data, thumbnail data (if available), and the status segment.
When it occurs in one frame, the thumbnail table will be the first one to be dropped. If
the spoof size is still not large enough to hold the data, compressed JPEG or thumbnail
data will be truncated so that the rest of status segment (excluding the thumbnail table)
is completed for the user's reference.
To avoid a spoof oversize error, the user has two alternatives:
• Assert spoof height ignore option
• Increase spoof width or spoof height
Parallel Output Interface
Protocol
The parallel output interface consists of the following signals.
• FV
• LV
• D
OUT
[7:0]
• PIXCLK
• pads_slew_rate
JPEG data or raw data are output on an 8-bit parallel data port D
OUT
[7:0] with the frame
valid (FV) signal to qualify JPEG frame timing, the data valid (LV) signal to qualify valid
data, and the output clock (PIXCLK). pads_slew_rate is used to control switching speed
of the clock signals.
Bypass mode, continuous mode, and spoof mode can run on the parallel output inter-
face.
Features
The following features are implemented for the user's convenience:
• PCLK can be turned on or off during frame blanking, which is configured by register
bit tx_control.en_clk_between_frames.
• In bypass or spoof mode, PCLK can be turned on or off during line blanking, which is
configured by register bit tx_control.en_clk_between_lines.
• In continuous mode, PCLK can be turned on or off when data is not valid, which is
configured by register bit tx_control.en_clk_invalid_data.
• In continuous mode, SOI or EOI can be inserted.
• In bypass mode, CCIR markers can be inserted, instead of po_fvld and po_dvld to
determine fame valid and line valid.
• Adaptive clock switching is supported on the parallel output interface.