VI.2 - Register Contents and Description (continued)

(*) = DEFAULT mode when NRESET pin is active (LOW level)

VI - REGISTERS (continued)

REGISTER_34-35-36-37 - ttx_block_[1:4]_def. : Teletext Block Definition

(Refer to Functional Description, Section IV.15)

MSB

LSB

register_34 txbd1

txbs1.3

txbs1.2

txbs1.1

txbs1.0

txbe1.3

txbe1.2

txbe1.1

txbe1.0

register_35 txbd2

txbs2.3

txbs2.2

txbs2.1

txbs2.0

txbe2.3

txbe2.2

txbe2.1

txbe2.0

register_36 txbd3

txbs3.3

txbs3.2

txbs3.1

txbs3.0

txbe3.3

txbe3.2

txbe3.1

txbe3.0

register_37 txbd4

txbs4.3

txbs4.2

txbs4.1

txbs4.0

txbe4.3

txbe4.2

txbe4.1

txbe4.0

These are four Teletext Block Definition registers, used in conjunctionwith Reg 38 (TeletextBlock Mapping).

Each of these registers defines a start line (TXBSx[3:0]) and an end line (TXBEx[3:0]). [TXBSx = Teletext

Block Start for block x, TXBEx = Teletext Block End for block x]

When applying to field1 :

TXBSx[3:0]=0 codes line 7,

...

TXBSx[3:0]=i codes line 7+i,

...

TXBSx[3:0]=15dec (‘1111’bin) codes line 7+15=22

When applying to field2 :

TXBSx[3:0]=0 codes line 320,

...

TXBSx[3:0]=i codes line 320+i,

...

TXBSx[3:0]=15dec (‘1111’bin) codes line 320+15=335

(ITU-R601/625 line numbering)

DEFAULT value: none, registers 34-37 are never reset.

REGISTER_38 - ttx_block_map : Teletext Block Mapping

MSB

LSB

register_38

txmf1.1

txmf1.2

txmf1.3

txmf1.4

txmf2.1

txmf2.2

txmf2.3

txmf2.4

(txmf1 stands for ’Teletext Block Mapping to field1, txmf2 stands for ’Teletext Block Mapping to field2)

This register allows to map the blocks of Teletext lines defined by registers 34 to 37 to either field1, field2

or both :

Its default value is “00000000”

txmf1.N defines whether txbdN (Nth teletext block, see reg34-37 above) applies to field 1,

txmf2.N defines whether txbdN (Nth teletext block, see reg34-37 above) applies to field 2.

In other words, if txmf1.N=1 then Teletext will be encoded in field 1 from the line defined by txbsN.[3:0]

(see above) to the line defined by txbeN.[3:0].

Similarly, if txmf2.N=1 then Teletext will be encoded in field 2 from the line defined txbsN.[3:0] (see above)

to the line defined by txbeN.[3:0].

STV0118

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