ASX340AT datasheet(19/54 Pages) ONSEMI

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ASX340AT

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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.

Figure 18. External Signal Processing Block Diagram

SPI

1KB to 16MB

27 MHz

VIDEO_P

EXTCLK

VIDEO_N

Signal processor

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

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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