Texas Instruments | TVP5146 PDC and VPS APPLICATION NOTE | Application notes | Texas Instruments TVP5146 PDC and VPS APPLICATION NOTE Application notes

Texas Instruments TVP5146 PDC and VPS APPLICATION NOTE Application notes
Application Report
SLEA017 – OCTOBER 2003
TVP5146 PDC and VPS APPLICATION NOTE
HPA Digital Audio Video
ABSTRACT
TVP5146 VBI SLICER EXAMPLE: EXTRACTING PDC AND VPS DATA
PDC (Program Delivery Control) is a signal intended for controlling VCRs. It is used only with The PAL
standard and it is received as part of WST (World Standard Teletext). PDC is used to control VCR
recording by informing a PDC-equipped VCR when a particular program starts and ends.
VPS (Video Program System) is an earlier scheme for controlling VCR recording. VPS is used
only with the PAL standard and it is received during line 16 of the VBI (Vertical Blanking
Interval).
In this application note, signals which model actual PDC and VPS signals are inserted into the
VBI of a PAL composite video signal which is input to the TVP5146 Video Decoder. The VBI
slicer data filter feature is used to extract only the desired PDC data packets. Complete register
settings are presented, as well as C source code for programming the device and extracting the
PDC and VPS data using status polling.
1
SLEA017 – OCTOBER 2003
1
I2C Register Settings
This section lists the register values to setup the TVP5146 for extraction of PDC and VPS data.
1.1
Direct Registers
Table 1 - Direct Register Settings lists the register values to setup the direct I2C registers of the
TVP5146 for extraction of PDC and VPS data. The address, data and description are given for
each register.
Table 1 - Direct Register Settings
TVP5146
DIRECT
ADDRESS
(HEX)
00
02
06
31
34
35
B1
B2
B3
B4
B5
B6
B7
B8
B9
BA
BB
DATA
(HEX)
0C
00
40
05
11
FA
F0
FF
F2
00
00
00
00
00
00
00
0D
C0
C1
D6
D7
D8
D9
DA
01
00
07
16
F0
00
FF
2
DESCRIPTION
Video Input = CVBS CH4
Standard = Auto-switch
Pedestal off
GLCO in ADI mode
Outputs active
GLCO and FID active
Magazine + Row LS Bit = 000 0 ( Magazine 8 )
Row 4 MS Bits
= 1111 ( Row = 11110 = 30 dec )
Type
= 0010 ( Type 2 )
Filter1 Mask4
Filter1 Mask5
Filter2 Mask1
Filter2 Mask2
Filter2 Mask3
Filter2 Mask4
Filter2 Mask5
NAND fcn, 5-byte header, Enable Filter 1
NOTE: Setting to 5-byte header allows filtering on the “Type 2” byte.
VBI FIFO access via I2C
Interrupt Line Number (not used)
VDP line start
VDP line stop
Global Line Mode, Teletext, F1, Filter ON
Disable full field
Full field mode
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
1.2
Indirect Registers
Table 2 - Indirect I2C Register Settings - lists the register values to setup the indirect I2C
registers of the TVP5146 for extraction of PDC and VPS data. This sets up a line mode register
which specifies the line number, data type, field and options for the VPS data.
Table 2 - Indirect I2C Register Settings
TVP5146
INDIRECT
ADDRESS
(HEX)
0x800600
0x800601
DATA
(HEX)
10
34
COMMENT
Line 16
VPS, Sliced data to registers only, Field 1,
1.2.1 Writing to Indirect Registers
The following example, illustrates how to write to an indirect register. To load the previous data
to the line address and line mode indirect registers:
1)
2)
Set the VBUS address to 0x800600.
•
Write 0x80 to I2C address 0xEA.
•
Write 0x06 to I2C address 0xE9.
•
Write 0x00 to I2C address 0xE8.
Write the data:
•
Write 0x10 to I2C address 0xE1. (Note register 0xE1 is the auto incrementing
VBUS register.
After writing to this register the internal VBUS address automatically increments to
0x800601).
•
Write 0x34 to I2C address 0xE1.
TVP5146 PDC and VPS APPLICATION NOTE
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SLEA017 – OCTOBER 2003
2
Program Delivery Control
2.1
PDC Input Data:
Since a PDC (Program Delivery Control) packet is sent on Teletext magazine 8, row number 30, type
code 2, the data filter is setup to accept only teletext lines matching these three parameters.
The magazine 8 is encoded as 000. Row 30 in binary is 11110. After bit reversal, the magazine and
row become 0000 1111. The type code is 0010. After Hamming encoding, the resulting teletext bytes
are 15h, EAh and 49h. TVP5146 is normally set to filter on up to two header bytes. In this example,
the data filter is set to allow filtering on up to 5 header bytes. This allows the third byte (Type Code) to
be used for filtering also.
The input data is four lines of teletext, which have been arbitrarily placed on odd field lines 7-10. Only
the teletext line on line 8 should pass thru the data filter.
The 40 bytes of teletext data are the same for each line. (The individual teletext lines in the output
data can be distinguished by the line number, which is inserted by TVP5146.) The PDS data was
sourced by a Norpak TES3.
4
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
Line 7: Magazine 8, Row 30, Type Code 1 => Discarded (wrong type code)
15
02
49
D0
6E
EC
EA
15
64
D0
E5
E5
15
A1
15
EC
76
EA
49
15
20
E9
EA
2F
43
34
73
EA
5E
68
20
E9
5E
FD
61
54
EF
15
B6
6E
E5
6E
Line 8: Magazine 8, Row 30, Type Code 2 => Accepted
15
49
49
D0
6E
EC
EA
15
64
D0
E5
E5
15
A1
15
EC
76
EA
49
15
20
E9
EA
2F
43
34
73
EA
5E
68
20
E9
5E
FD
61
54
EF
15
B6
6E
E5
6E
Line 9: Magazine 8, Row 29, Type Code 2 => Discarded (wrong row #)
02
49
49
D0
6E
EC
2F
15
64
D0
E5
E5
15
A1
15
EC
76
EA
49
15
20
E9
EA
2F
43
34
73
EA
5E
68
20
E9
5E
FD
61
54
EF
15
B6
6E
E5
6E
Line 10: Magazine 3, Row 30, Type Code 2 => Discarded (wrong magazine)
38
49
49
D0
6E
EC
EA
15
64
D0
E5
E5
15
A1
15
EC
76
EA
49
15
20
E9
EA
2F
43
34
73
EA
5E
68
20
E9
5E
FD
61
54
EF
15
B6
6E
E5
6E
TVP5146 PDC and VPS APPLICATION NOTE
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SLEA017 – OCTOBER 2003
2.2
PDC Output Data
Below is the output data which was read from the VBI FIFO. The total number of bytes
received for each line of teletext was 52. The data shown was repeated many times. The
following table describes the output data:
00
27
EA
5E
68
20
E9
FF
15
5E
FD
61
54
EF
FF
EA
15
B6
6E
E5
6E
91
49
49
D0
6E
EC
BA
78
15
64
D0
E5
E5
4B
15
A1
15
EC
76
08
EA
49
15
20
E9
0C
EA
2F
43
34
73
Table 3 - PDC Output Data via the VBI FIFO
DATA ITEM
VALUE(S)
COMMENT
(HEX)
PREAMBLE
00, FF, FF
DID
91
Sliced data of VBI lines of first field
SDID
78
From the Global Line Mode register: Teletext mode
NN
4B
0x0B = 11 x 4 = 44 bytes (counting from the 9th byte to the
end)
IDID0
08
Line number 8
IDID1
0C
Status – Match#1, Match#2
SYNC
27
Sync Pattern
MAGAZINE & ROW
DATA
15, EA
49, 15, 15,…,6E
CHECKSUM
BA
3
Video Program System
3.1
VPS Input Data:
6
Preamble
DeHams to 0000, 1111 => Magazine 8, Row 30
40 bytes. First byte is type code 2.
Checksum
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
VPS input data is from the Fluke 54200 TV Signal Generator, VPS data set #1.
3.2
VPS Output Data:
3.2.1 Via VPS Registers:
The data captured from TVP5146 in VPS mode using the VPS registers and status polling is
shown in the following.
This data was repeated many times.
FF FF 42 FF FF FF FF FF 71 8E 7B 41 00
3.2.2 Via VBI FIFO
VPS byte number ->
3
00 FF FF 91 BC 44 10 0C
FF FF 42 FF FF FF FF FF 71 8E 7B 41 00 F6 00
<-
TVP5146 Header
4
5
6
7
8
9
10 11 12 13 14 15 CS PAD PAD
00
->
NOTE: For VPS, the run-in clock and sync bytes are counted as bytes 1 & 2.
TVP5146 PDC and VPS APPLICATION NOTE
7
SLEA017 – OCTOBER 2003
Table 4 - VPS Data via the VBI FIFO
DATA ITEM
VALUE(S)
COMMENT
(HEX)
PREAMBLE
8
00, FF, FF
Preamble
DID
91
Sliced data of VBI lines of first field
SDID
BC
from the Line Mode Register of line 16: VPS mode.
NN
44
NN = 4. 4 x 4 = 16 bytes (counting from the VPS byte #3 to
the end). Two fill bytes are inserted at the end to make a
multiple of 4 bytes.
IDID0
10
Line number 16 decimal
IDID1
0C
Status – Match#1, Match#2
BYTES 3-4 AND 6-10
FF,FF,FF,FF,FF
BYTES 5 AND 11-15
42,71,8E,7B,41, 00
CHECKSUM
F6
FILL BYTES
00,00
Not used by VPS
VPS Data (see analysis below)
Checksum
Inserted to make a multiple of 4 bytes.
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
Figure 1 VPS Data Format from ETS 300 231
TVP5146 PDC and VPS APPLICATION NOTE
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SLEA017 – OCTOBER 2003
3.3
Analysis of VPS Data
From the document ETS 300 231 subtitiled Television systems;
Specification of the domestic video Programme Delivery Control system (PDC),
In that document, Figure 9, “Data format of the programme delivery data in the dedicated TV
line”, Describes the format o f the VPS data.
The analysis below shows how this data is decoded to
generate the correct time stamp: Dec 24 14:30
byte
5 = 0100 0010
PCS = 0100 = 4
CNI[1-4] = 0010 = 2
byte 11 = 0111 0001
CNI[9-10] = 01
DAY = 11000 = 24
byte 12 = 1000 1110
MONTH = 1100 = DEC HOUR = 01110 = 14:00
byte 13 = 0111 1011
MINUTE = 01 1110 = 30
byte 14 = 0100 0001
COUNTRY = 1101 NETWORK = 000001
CNI[5-8] = 0100
byte 15 = 0000 0000
CNI[11-16] = 00 0001
PTY = 0000 0000
CNI = 0010 0100 0100 0001 = 2441h
Result: Dec 24 14:30
This is the correct result and matches the description given by the Fluke 54200 for this data
set.
10
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
//////////////////////////////////////////////////////////////////
//
// PDC_VPS.H
TEXAS INSTRUMENTS
BY: MICHAEL A. TADYSHAK
//
// Function prototypes
//
//////////////////////////////////////////////////////////////////
void
void
void
void
void
void
void
CmdStartVBIFIFO( BYTE *pBuf );
InitializePDCVPS();
TVP5146GeneralSetup();
ResetLineModeRegisters();
LoadLineModeRegisters();
SetupDataFilter();
SetupVDP();
void
void
void
void
void
void
void
void
PollVBIFIFO( void );
PollPDCVPS( int* pPDCAvail, int* pVPSAvail );
HandleFIFO();
HandleVPS();
BlockReadVPSRegisters( unsigned char* p );
PollFIFOThresh( int* pFIFOThresh );
DoHouseKeeping();
DoVPSHouseKeeping();
TVP5146 PDC and VPS APPLICATION NOTE
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SLEA017 – OCTOBER 2003
Retrieving the PDC and VPS data using status polling (source code)
//////////////////////////////////////////////////////////////////
//
// PDC_VPS.C
TEXAS INSTRUMENTS
BY: MICHAEL A. TADYSHAK
//
//////////////////////////////////////////////////////////////////
//
// This code demonstrates how to retrieve PDC and VPS
// VBI data from the TVP5146 using status polling.
//
//////////////////////////////////////////////////////////////////
#include "PDC_VPS.h"
#define NUM_MODE_REGISTERS
#define NUM_VPS_REGISTERS
#define NUM_PDC_BYTES
#define MASK_FIFO_THRESH
#define MASK_PDC_AVAIL
#define MASK_VPS_AVAIL
9
13
52
0x80
0x40
0x10
extern
EXTRACT_TTX_PARAMS g_stTTX;
extern
BYTE g_pComBuf[];
extern BYTE g_pVBIBuffer[];
extern BYTE g_pVPSBuffer[];
12
// Structure containing teletext controls
//
and buffer management variables
// Serial port communication buffer
// 32KB buffer for PDC data
// 32KB buffer for VPS data
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
//////////////////////////////////////////////////////////////////
// CmdStartVBIFIFO()
//////////////////////////////////////////////////////////////////
// Initializes the program variables (buffer management, etc.).
// Initializes the TVP5146 for auto-switch mode.
// Initializes to receive PDC and VPS data.
// Kicks off polling.
//////////////////////////////////////////////////////////////////
void CmdStartVBIFIFO( BYTE *pBuf )
{
DWORD dwBufferSize = 0ul;
BYTE* pTop
= pBuf;
BYTE nData
= 0;
int bPDC = FALSE;
int bVPS = FALSE;
// Get arguments
pBuf += 2;
g_stTTX.nIntType
g_stTTX.nTTXMode
// Skip side
pBuf++;
g_stTTX.nIntLineNum
g_stTTX.nIntField
g_stTTX.nIntThresh
dwBufferSize
pBuf++;
dwBufferSize
pBuf++;
dwBufferSize
pBuf++;
dwBufferSize
pBuf++;
= *pBuf++;
= *pBuf++;
= *pBuf++;
= *pBuf++;
= *pBuf++;
+= (DWORD)(*pBuf);
+= (DWORD)(*pBuf) <<
8ul;
+= (DWORD)(*pBuf) << 16ul;
+= (DWORD)(*pBuf) << 24ul;
// Initialize extract teletext parameters to default values
g_stTTX.wBufferSize
= (WORD)dwBufferSize;
g_stTTX.wBytesInBuffer = 0u;
g_stTTX.wBytesAvail
= g_stTTX.wBufferSize;
g_stTTX.wByteCnt
= 0u;
g_stTTX.pBuffer
= &(g_pVBIBuffer[0]);
g_stTTX.bBufferFull
= FALSE;
g_stTTX.wVPSBufferSize
g_stTTX.wVPSBytesInBuffer
g_stTTX.wVPSBytesAvail
g_stTTX.wVPSByteCnt
g_stTTX.pVPSBuffer
g_stTTX.bVPSBufferFull
=
=
=
=
=
=
(WORD)dwBufferSize;
0u;
g_stTTX.wVPSBufferSize;
0u;
&(g_pVPSBuffer[0]);
FALSE;
// -------// Initialize for PDC and VPS data
InitializePDCVPS();
TVP5146 PDC and VPS APPLICATION NOTE
13
SLEA017 – OCTOBER 2003
// Fill the buffer with TTX transfers
PollVBIFIFO();
// Return to polling for serial port commands
return;
}
14
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
//////////////////////////////////////////////////////////////////
// Initialization
//////////////////////////////////////////////////////////////////
void InitializePDCVPS()
{
// Load general setup
TVP5146GeneralSetup();
// Reset line mode registers
ResetLineModeRegisters();
// Reset VBI status bits
WriteTVP5146( 0xF6, 0x50 );
// Reset the FIFO to empty
WriteTVP5146( 0xBF, 0x00 );
// Clear interrupt masks
WriteTVP5146( 0xF4, 0x00 );
WriteTVP5146( 0xF5, 0x00 );
SetupDataFilter();
SetupVDP();
LoadLineModeRegisters();
}
void TVP5146GeneralSetup()
{
WriteTVP5146( 0x00, 0x0C
WriteTVP5146( 0x02, 0x00
WriteTVP5146( 0x06, 0x40
WriteTVP5146( 0x34, 0x11
WriteTVP5146( 0x35, 0xFA
WriteTVP5146( 0x31, 0x05
}
);
);
);
);
);
);
//
//
//
//
//
//
Video Input = CVBS CH4
Standard = Auto-switch
Pedestal off
Outputs active
GLCO and FID active
GLCO in ADI mode
TVP5146 PDC and VPS APPLICATION NOTE
15
SLEA017 – OCTOBER 2003
void ResetLineModeRegisters()
{
int i = 0;
int nNumBytes = NUM_MODE_REGISTERS << 1;
// Set the VBUS address to 0x800600.
WriteTVP5146( 0xEA, 0x80 );
WriteTVP5146( 0xE9, 0x06 );
WriteTVP5146( 0xE8, 0x00 );
// Set all line addresses to 0x00
// Set all line mode registers to unused (0xFF)
for( i=0; i<nNumBytes; i+=2 )
{
// Write to auto-incrementing data register
WriteTVP5146( 0xE1, 0x00 );
WriteTVP5146( 0xE1, 0xFF );
}
}
void SetupDataFilter()
{
// Data filter #1 WriteTVP5146( 0xB1,
WriteTVP5146( 0xB2,
WriteTVP5146( 0xB3,
WriteTVP5146( 0xB4,
WriteTVP5146( 0xB5,
Mask
0xF0
0xFF
0xF2
0x00
0x00
and Pattern settings
);
// Magazine + Row LS Bit = 0000 (Magazine 8)
);
// Row 4 MS Bits
= 1111 (Row 30)
);
// Type code 2
);
);
// Data filter #2 WriteTVP5146( 0xB6,
WriteTVP5146( 0xB7,
WriteTVP5146( 0xB8,
WriteTVP5146( 0xB9,
WriteTVP5146( 0xBA,
Mask
0x00
0x00
0x00
0x00
0x00
and Pattern settings
);
);
);
);
);
// Filter control register
// NAND function
// NABTS 5-byte header
// Enable filter #1
// NOTE: Setting to 5-byte header allows filtering on the Type Code byte
WriteTVP5146( 0xBB, 0x0D );
}
16
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
void SetupVDP()
{
WriteTVP5146( 0xD6, 0x07 );
WriteTVP5146( 0xD7, 0x16 );
WriteTVP5146( 0xD8, 0xF0 );
WriteTVP5146( 0xC0, 0x01 );
WriteTVP5146( 0xD9, 0x00 );
WriteTVP5146( 0xDA, 0xFF );
//
//
//
//
VDP line start at line 7
VDP line stop at line 22
Global Line Mode:
WST teletext (PDC), Field 1, FIFO, Filter on
// VBI FIFO access via I2C
// Disable full field
// Full field mode
}
void LoadLineModeRegisters()
{
// Set the VBUS address to 0x800600.
WriteTVP5146( 0xEA, 0x80 );
WriteTVP5146( 0xE9, 0x06 );
WriteTVP5146( 0xE8, 0x00 );
// VPS: Line 16, Field 1, Registers only, Filter disabled
// Write to auto-incrementing data register
WriteTVP5146( 0xE1, 0x10 );
WriteTVP5146( 0xE1, 0x34 );
}
TVP5146 PDC and VPS APPLICATION NOTE
17
SLEA017 – OCTOBER 2003
//////////////////////////////////////////////////////////////////
// PollVBIFIFO()
//////////////////////////////////////////////////////////////////
// Main polling loop.
// Polls for PDC and VPS data
// Waits for a full buffer or STOP command from PC.
//////////////////////////////////////////////////////////////////
// Call PollPDCVPS() to get PDC from VBI FIFO and VPS from registers.
// Call PollFIFOThresh() to get all data from the VBI FIFO.
// In the "all to FIFO" case, the mode register for VPS must be
// changed from 34h to 74h.
//////////////////////////////////////////////////////////////////
void PollVBIFIFO( void )
{
int bPDC = FALSE;
int bVPS = FALSE;
int bThresh = FALSE;
while( !g_stTTX.bBufferFull && !g_stTTX.bVPSBufferFull )
{
// Test if PC has requested to abort data extraction
if( CTS == 0 )
{
// Set BUFFER_FULL_FLAG
g_stTTX.bBufferFull = TRUE;
g_stTTX.bVPSBufferFull = TRUE;
}
// Poll for PDC and VPS data
PollPDCVPS( &bPDC, &bVPS );
// Call this instead to read VPS data from the FIFO
// PollFIFOThresh( &bThresh );
}
// Buffer is now full or stop was hit
g_stTTX.bBufferFull = FALSE;
g_stTTX.bVPSBufferFull = FALSE;
// Reset buffer pointer to beginning
g_stTTX.pBuffer
= &(g_pVBIBuffer[0]);
g_stTTX.pVPSBuffer
= &(g_pVPSBuffer[0]);
// Signal to PC that data extraction to buffer is complete
RTS = 0;
return;
}
18
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
//////////////////////////////////////////////////////////////////
// PollPDCVPS()
//////////////////////////////////////////////////////////////////
// Reads TVP5146 status flags:
//
TTX Data Available
//
VPS Data Available
// Resets the individual status flags if set
// For PDC, calls routine to read the VBI FIFO
// For VPS, calls routine to read the VPS registers
//////////////////////////////////////////////////////////////////
void PollPDCVPS( int* pPDCAvail, int* pVPSAvail )
{
int nStatus = ReadTVP5146( 0xF0 );
int nPDC = nStatus & MASK_PDC_AVAIL;
int nVPS = nStatus & MASK_VPS_AVAIL;
*pPDCAvail = *pVPSAvail = FALSE;
if( !nPDC && !nVPS )
{
return;
}
if( nPDC )
{
*pPDCAvail = TRUE;
// Reset PDC available status
WriteTVP5146( 0xF6, MASK_PDC_AVAIL );
HandleFIFO();
}
if( nVPS )
{
*pVPSAvail = TRUE;
// Reset VPS available status
WriteTVP5146( 0xF6, MASK_VPS_AVAIL );
HandleVPS();
}
return;
}
TVP5146 PDC and VPS APPLICATION NOTE
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SLEA017 – OCTOBER 2003
//////////////////////////////////////////////////////////////////
// PollFIFOThresh()
//////////////////////////////////////////////////////////////////
// Reads TVP5146 status flags:
//
FIFO threshold reached
// Resets the status flag if set
// Calls routine to read the VBI FIFO
//////////////////////////////////////////////////////////////////
void PollFIFOThresh( int* pFIFOThresh )
{
int nStatus = ReadTVP5146( 0xF0 );
*pFIFOThresh = FALSE;
if( nStatus & MASK_FIFO_THRESH )
{
*pFIFOThresh = TRUE;
// Reset status
WriteTVP5146( 0xF6, MASK_FIFO_THRESH );
HandleFIFO();
}
return;
}
20
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
//////////////////////////////////////////////////////////////////
// HandleFIFO()
//////////////////////////////////////////////////////////////////
// Gets count of words in VBI FIFO.
// Multiply by 2 to convert from words to bytes.
// Read that number of bytes from VBI FIFO in one I2C transfer.
// Perform buffer management (housekeeping).
//////////////////////////////////////////////////////////////////
void HandleFIFO()
{
int i = 0;
// Get the number of bytes in FIFO
g_stTTX.wByteCnt = ReadTVP5146( 0xBC ) << 1;
if( g_stTTX.wByteCnt == 0 )
{
return;
}
// If bytes to read from FIFO is more than available space in buffer
// Decrease number of bytes to read until it fits in buffer
// Set buffer full flag
while( (WORD)g_stTTX.wByteCnt > g_stTTX.wBytesAvail )
{
g_stTTX.wByteCnt--;
g_stTTX.bBufferFull = TRUE;
}
if( g_stTTX.wByteCnt == 0 )
{
g_stTTX.bBufferFull = TRUE;
}
else
{
// Read VBI FIFO to data buffer
BlockReadTVP5146( 0xE2, g_stTTX.wByteCnt, g_stTTX.pBuffer );
DoHouseKeeping();
}
}
TVP5146 PDC and VPS APPLICATION NOTE
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SLEA017 – OCTOBER 2003
//////////////////////////////////////////////////////////////////
// HandleVPS()
//////////////////////////////////////////////////////////////////
// Sets byte count to 13.
// Reads that number of bytes from VPS registers in one I2C transfer.
// Perform buffer management (housekeeping).
//////////////////////////////////////////////////////////////////
void HandleVPS()
{
g_stTTX.wVPSByteCnt = NUM_VPS_REGISTERS;
// If bytes to read from VPS registers is more than available space in buffer
// Decrease number of bytes to read until it fits in buffer
// Set buffer full flag
while( (WORD)g_stTTX.wVPSByteCnt > g_stTTX.wVPSBytesAvail )
{
g_stTTX.wVPSByteCnt--;
g_stTTX.bVPSBufferFull = TRUE;
}
if( g_stTTX.wVPSByteCnt == 0 )
{
g_stTTX.bVPSBufferFull = TRUE;
}
else
{
// Read from VPS registers
BlockReadVPSRegisters( g_stTTX.pVPSBuffer );
DoVPSHouseKeeping();
}
}
22
TVP5146 PDC and VPS APPLICATION NOTE
SLEA017 – OCTOBER 2003
//////////////////////////////////////////////////////////////////
// BlockReadVPSRegisters()
//////////////////////////////////////////////////////////////////
// Sets byte count to 13.
// Load VPS registers VBUS address 0x800700.
// Reads the stored number of bytes from VPS registers in one
// I2C transfer.
//////////////////////////////////////////////////////////////////
void BlockReadVPSRegisters( unsigned char* pBuf )
{
// Set the VBUS address to 0x800700.
WriteTVP5146( 0xEA, 0x80 );
WriteTVP5146( 0xE9, 0x07 );
WriteTVP5146( 0xE8, 0x00 );
// Read the data
// Read auto-incrementing data register
BlockReadTVP5146( 0xE1, g_stTTX.wVPSByteCnt, pBuf );
}
void DoHouseKeeping()
{
WORD w = 0;
// Increase count of bytes in buffer
g_stTTX.wBytesInBuffer += g_stTTX.wByteCnt;
// Advance buffer pointer
g_stTTX.pBuffer
+= g_stTTX.wByteCnt;
// Decrease bytes available in buffer
g_stTTX.wBytesAvail
-= g_stTTX.wByteCnt;
}
void DoVPSHouseKeeping()
{
// Increase count of bytes in buffer
g_stTTX.wVPSBytesInBuffer += g_stTTX.wVPSByteCnt;
// Advance buffer pointer
g_stTTX.pVPSBuffer
+= g_stTTX.wVPSByteCnt;
// Decrease bytes available in buffer
g_stTTX.wVPSBytesAvail
-= g_stTTX.wVPSByteCnt;
}
//////////////////////////////////////////////////////////////////
//
//
THE END
//
//////////////////////////////////////////////////////////////////
TVP5146 PDC and VPS APPLICATION NOTE
23
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