Content Based Data Update - Analog Devices Advantiv ADV7604 Hardware Manual

These steps can be summed up in the following pseudo code :
// CODE USED BY THE USER FOR SLICED "PDC" DATA READING
Byte vdp_status_read_out;
vdp_status_addr = 0x78h;
vdp_output_sel_addr = 0x9Ch;
I2C_write_byte (vdp_output_sel_addr, 0x80h);
// CLEARING GS_PDC_VPS_UTC AVL BITS IN VDP_STATUS REG
I2C_write_byte (vdp_status_addr, 0x10h);
I2C_read_byte (vdp_status_addr, vdp_status_read_out);
While (vdp_status_read_out [4] == 1'b0)
I2C_read_byte (vdp_status_addr, vdp_status_read_out);
I2C_read_multiple_bytes (0x84h, 13, pdc_bytes);

11.9.2 Content Based Data Update

For certain standards like WSS, CGMS, GemStar, PDC, UTC, and VPS, the information content in
the transmitted signal remains the same over numerous lines and the user may want to be notified
only when there is a change in the information content or loss of the information content.
The user needs to enable the content based update for the required standard through the
GS_VPS_PDC_UTC_CGMSTB and WSS_CGMS_CB_CHANGE bits. Thus, the available status bit
will show the availability of that standard only when there is a change in its content.
The content based update also applies to loss of data at the lines where some data was present
previously. For standards like VPS, GemStar, CGMS, and WSS, if there is no data arrival in the next
four lines programmed, the corresponding available bit in the VDP_STATUS register is set to high
and the content in the I
clear bit so that whenever a valid line is decoded after some time, the decoded results are available
2
into the I C registers, with the available status bit set to high.
If content based updating is enabled, the available status bit is set to high (assuming the clear bit was
written) in the following cases:
• Data contents change
• There was some data being decoded and four lines with no data are detected
• There was no data being decoded and new data is being decoded
GS_VPS_PDC_UTC_CB_CHANGE (VDP) , VDP Map, Address 0x9C, [5]
GS_VPS_PDC_UTC_CB_CHANGE enables content based update for GemStar, VPS, PDC, and
UTC.
Function
GS_VPS_PDC_UTC_CB_
CHANGE
0
1
Rev. F August 2010
2
C registers for that standard is set to zero. The user has to write high to the
Description
Disables content based updating of VPS, PDC, UTC data
Enables content based updating of VPS, PDC, UTC data
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