Interrupt Based Reading Of I C Registers - Analog Devices Advantiv ADV7604 Hardware Manual

WSS_CGMS_CB_CHANGE (VDP) , VDP Map, Address 0x9C, [4],
WSS_CGMS_CB_CHANGE enables content based update for WSS and CGMS.
Function
WSS_CGMS_CB_CHANGE
0
1
11.10 Interrupt Based Reading of I
Some VDP status bits are also linked to the interrupt request controller so that the user does not have
to poll the available status bit. The user can configure the video decoder to trigger an interrupt
request on the INTRQ pin in response to the valid data available in I
available for the following data types:
• CGMS or WSS
The user can select between triggering an interrupt request each time sliced data is available
or triggering an interrupt request only when the sliced data has changed. Selection is via the
WSS_CGMS_CB_CHANGE bit.
• GemStar, PDC, VPS or UTC
The user can select between triggering an interrupt request each time sliced data is available
or triggering an interrupt request only when the sliced data has changed. Selection is via the
GS_VPS_PDC_UTC_CB_CHANGE bit.
Follow these steps for the interrupt based reading of the VDP I
standard.
1. Unmask the interrupt bit, for example, CCAP bit (User Map 1, Address 0x55 [0] = 1). CCAP
data occurs on the incoming video. VDP slices CCAP data and places it in the VDP readback
registers.
2. The VDP CCAP available bit goes high and the VDP module signals to the interrupt
controller to stimulate an interrupt request (for CCAP in this case).
3. Read the interrupt status bits in User Map 1 I
available (User Map 1, Address 0x52 [0] = 1).
4. Write 1 to the CCAP interrupt clear bit (User Map 1, Address 0x53 [0] = 1) in the interrupt
2
I C space (this is a self clearing bit). This clears the interrupt on the interrupt pin but does not
have an effect in the VDP I
5. Read the CCAP data from the VDP I
6. Write to the STATUS_CLEAR_CCAP bit (VDP Map, Address 0x78 [0] = 1) to signify that
CCAP data has been read (the VDP CCAP can be updated at the next occurrence of CCAP).
7. Return to step 2.
Rev. F August 2010
Description
Disables content based update of WSS, CGMS data
Enables content based update of WSS, CGMS data
2
C Registers
2
C space and see that new CCAP data is
2
C area.
2
C area.
340
2
C registers. This function is
2
C data registers for the CCAP
ADV7604