ASX340AT Datasheet, PDF (31/75 Pages) ON Semiconductor – Color CMOS NTSC/PAL Digital Image

ASX340CS: 1/4-Inch Color CMOS NTSC/PAL Digital Image Sensor
External Signal Processing
Host Command Interface
ON Semiconductor sensors and SOCs contain numerous registers that are accessed
through a two-wire interface with speeds up to 400 kHz.
The ASX340AT in addition to writing or reading straight to/from registers or firmware
variables, has a mechanism to write higher level commands, the Host Command Inter-
face (HCI). Once a command has been written through the HCI, it will be executed by
on-chip firmware and the results are reported back. In general, registers should not be
accessed with the exception of registers that are marked for “User Access.”
EEPROM or Flash memory is also available to store commands for later execution.
Under DMA control, a command is written into the SOC and executed.
For a complete description of host commands, refer to the ASX340AT Host Command
Interface Specification.
Figure 15: Interface Structure
bit 15 14
Addr 0x40
1
0
Host Command to FW
Response from FW
0
command register
door bell
bit 15
Addr 0xFC00
Addr 0xFC02
Addr 0xFC04
Addr 0xFC06
Addr 0xFC08
Addr 0xFC0A
Addr 0xFC0C
Addr 0xFC0E
Parameter 0
Parameter 7
0
cmd_handler_params_pool_0
cmd_handler_params_pool_1
cmd_handler_params_pool_2
cmd_handler_params_pool_3
cmd_handler_params_pool_4
cmd_handler_params_pool_5
cmd_handler_params_pool_6
cmd_handler_params_pool_7
ASX340AT/D Rev. H, 8/15 EN
31
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