Reset
FORCERXMODE_IO = 0x0
No stop state detected
(at least 1 lane)
FORCERXMODE_IO = 0x1
Stop state detected
(all lanes)
FORCERXMODE_IO = 0x0
or
time-out
Rx mode
NoRx mode
Rx mode
+
counter
camisp-254
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Camera ISP Functional Description
The state-machine controlling the RxMode is presented in
.
Figure 6-74. Camera ISP CSI2 RxMode and StopState FSM
6.4.3.10 Camera ISP CSI2 Data Decompression
The data compression technique used is differential pulse code modulation (DPCM) and pulse code
modulation (PCM).
The CSI2 receiver performs on-the-fly decompression. The decompressed data is either passed to the
Video processing hardware or stored in memory.
The data compression method is lossy and does not require any information outside the current
encoded/decoded line. This means that all the image lines can be encoded/decoded separately.
There are two different predictors used:
•
The simple predictor
This predictor uses only the previous same color component value as a prediction value. Therefore,
only two-pixel memory is required.
•
The advanced predictor
This predictor uses four previous pixel values, when the prediction value is evaluated. This means that
also the other color component values are used, when the prediction value has been defined.
The preferable usage is that simple predictor is used with 10 bits to 8 bits conversion (10 8 10) and the
advanced predictor is used with 10 bits to 7 bits and 10 bits to 6 bits conversions (10 7- 10 and 10 6 10).
The advanced predictor gives slightly better prediction for pixel value and so the image quality can be
improved with it. The simple predictor is very simple and so the processing power and the memory
requirements are reduced with it, when the image quality anyway is high enough.
To select DPCM decompression predictor for CSI2 Interface, set the
[10] DPCM_PRED
to 1 for simple predictor or to 0 for advanced predictor.
6.4.3.11 Camera ISP CSI2 EndOfFrame and EndOfLine pulses
The CSI2 receiver generates two signals to qualify the last pixel of a frame and the last pixel of a line.
Software can enable/disable generation of those signals for each context using the
EOF_EN and
[6] EOL_EN registers.
1187
SWPU177N – December 2009 – Revised November 2010
Camera Image Signal Processor
Copyright © 2009–2010, Texas Instruments Incorporated