VP310

PRELIMINARY DATA

22

2.6 DSS mode of acquisition

This mode is very similar to the DVB mode, except that the Symbol rate is fixed at 20 MBaud.

Two code rates are used: DSS-A uses 2/3 or DSS-B uses 6/7. These are programmed in the

register (127) CONFIG. If the code rate is unknown, program both DSS-A and DSS-B to force the

VP310 to do a code rate search. After changing the CONFIG register, a delay of 150µs should be

enforced before programming the RESET register. The Tuner may be programmed via the GPP

during this delay period.

Since both symbol rate and code rate are defined by programming the CONFIG register, the

contents of registers (23-24) SYM_RATE and register (25) VIT_MODE are ignored in DSS mode.

Enable VP310 : Program CONFIG

eg DSS-A

Reg 127 = 166 (A8hex)

Program tuner via GPP in 'pass through mode'

open port with Reg 20 = 64 (40hex)

send TUNER DATA via I2C bus (5 bytes).

close port with Reg 20 = 0

Reset VP310 to default register settings

Reg 21 = 128 (80hex)

Set AGC_SL (if required)

Initialise registers: reg 25 = 16 (10hex);

reg 49 = 50 (32 hex) ; reg 50 = 20 (14hex);

reg 86 = 20 (14hex); reg 87 = 18 (12hex);

reg 88 = 2; reg 89 = 1; reg 90 = 0;

reg 91 = 0; reg 92 = 0; reg 93 = 0.

DiSEqC mode

eg Horizontal with 22kHz on:

Reg 22 = 65 (41hex)

GO

Re-acquire signal

Reg 27 = 1

Figure 18. Initialisation sequence in DSS mode.