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Architecture
1775
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Video Port Interface (VPIF)
35.2.9 Initialization
The general procedure for VPIF initialization is:
1. Enable the VPIF in the LPSC.
2. Program the corresponding bits in the DMA size control register (REQSIZE) and the channel
n
sub-
picture configuration register (C
n
SUBPIC).
3. Program the Emulation related registers, such as the emulation suspend control register (EMUCTRL)
in the VPIF and the emulation suspend source register (SUSPSRC) in the System Module (see
for more detail). The default values of SUSPSRC are configured to the ARM
as the main processor.
35.2.10 Interrupt Support
Interrupt Events and Requests
The VPIF sends the following interrupt events to the CPU:
•
FRAME0
•
FRAME1
•
FRAME2
•
FRAME3
•
ERROR
The ERROR interrupt is generated for the following reasons:
•
For channels 0 or 1:
–
Internal buffer overflow
–
Length of EAV2SAV or SAV2EAV is not the same as the configured value
–
Bit error detected on 4th field of TRC
•
For channels 2 or 3:
–
Internal buffer overflow
Note that the VPIF peripheral has no mechanism to reissue interrupts that may have been dropped by the
CPU so care should be taken when VPIF interrupts are combined at the system level. In a combined
interrupt configuration, the CPU may be busy servicing a VPIF interrupt when another VPIF interrupt
arrives. If the interrupt controller has no means to count VPIF interrupts, the CPU will drop subsequent
VPIF interrupts until servicing of the first VPIF interrupt is complete.
Field/Frame Interrupts to CPU
This section describes the conditions of the field/frame based interrupt assertion from the VPIF. The VPIF
interrupt is designed to make the processor identify the timing for updating the address register of the
VPIF module. The timing of the interrupt from the VPIF module is different from the timing of the V-sync.
The interrupt is generated when the last data transfer between the VPIF module and the VBUS is finished.
Interrupt Condition
The interrupt signal from the VPIF described in this section means the beginning of a field (or frame). A
way to indicate the beginning of a field (or a frame) varies from the function mode; normal YC
receive/transmit mode and CCD/CMOS capture mode differ because of the vertical synchronization signal.
The VPIF generates the following events as conditions for interrupt assertion:
•
In normal YC receive/transmit mode, EAV on line L1 (and EAV on line L7 in field interrupt for bottom
field). Both L1 and L7 are described in
and
•
In CCD/CMOS capture mode, starting edge for first line of vertical valid pixel area.