ASX340AT_16 Datasheet, PDF (19/54 Pages) ON Semiconductor – 1/4‐inch Color CMOS NTSC/PAL Digital Image SOC

ASX340AT
EXTERNAL SIGNAL PROCESSING
An external signal processor can take data from ITU656
or raw Bayer output format and post-process or compress
the data in various formats.
27 MHz
EXTCLK
SPI
1KB to 16MB
VIDEO_P
VIDEO_N
D
Signal processor
Figure 18. External Signal Processing Block Diagram
Device Configuration
After power is applied and the device is out of reset by
de-asserting the RESET_BAR pin, it will enter a boot
sequence to configure its operating mode. There are
essentially three three configuration modes:
Flash/EEPROM Config, Auto Config, and Host Config.
Figure 14: “Power-Up Sequence – Configuration Options
Flow Chart,” contains more details on the configuration
options.
The SOC firmware supports a System Configuration
phase at start-up. This consists of five modes of execution:
1. Flash Detection
2. Flash-Config
3. Auto-Config
4. Host-Config
5. Change-Config (commences streaming −
completes the System Configuration mode).
The System Configuration phase is entered immediately
after the firmware initializes following SOC power-up or
reset. By default, the firmware first enters the Flash
Detection mode.
The Flash Detection mode attempts to detect the presence
of an SPI Flash or EEPROM device:
• If no device is detected, the firmware then samples the
SPI_SDI pin state to determine the next mode:
− If SPI_SDI = 0 then it enters the Host-Config
mode.
− If SPI_SDI = 1 then it enters the Auto-Config
mode.
• If a device is detected, the firmware switches to the
Flash-Config mode.
In the Flash-Config phase, the firmware interrogates the
device to determine if it contains valid configuration
records:
• If no records are detected, then the firmware enters the
Auto-Config mode.
• If records are detected, the firmware processes them.
By default, when all Flash records are processed the
firmware switches to the Host-Config mode. However,
the records encoded into the Flash can optionally be
used to instruct the firmware to proceed to one of the
other mode (auto-config/change-config).
The Auto-Config mode uses the FRAME_VALID,
LINE_VALID, DOUT_LSB0 and DOUT_LSB1 pins to
configure the operation of the device, such as video format
and pedestal (refer to the Developer Guide for more details).
After Auto-Config completes the firmware switches to the
Change-Config mode.
In the Host-Config mode, the firmware performs no
configuration, and remains idle waiting for configuration
and commands from the host. The System Configuration
phase is effectively complete and the SOC will take no
actions until the host issues commands.
In the Change-Config mode, the firmware performs a
“Change-Config” operation. This applies the current
configuration settings to the SOC, and commences
streaming. This completes the System Configuration phase.
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