ASX340AT Datasheet, PDF (28/75 Pages) ON Semiconductor – Color CMOS NTSC/PAL Digital Image

ASX340CS: 1/4-Inch Color CMOS NTSC/PAL Digital Image Sensor
External Signal Processing
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,” on page 29 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 Detec-
tion 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.
ASX340AT/D Rev. H, 8/15 EN
28
©Semiconductor Components Industries, LLC, 2015.