VP310

PRELIMINARY DATA

20

2.5 Channel change sequence with Search mode

If the signal parameters are unknown, it is possible to instruct the VP310 to find a digital signal

and report the parameters found. Registers 24 and 25 are programmed with the expected

range(s) and the search mode bit SYM_RATE[B15] is set high. A code rate search is forced by

programming more than one bit in VIT_MODE (26) register.

Note: code rate 6/7 is not searched for DVB mode.

If a signal with the specified symbol rate range (or ranges) is not found in the frequency range

searched, a QPSK Baud End interrupt (Bit B6, QPSK_INT_L (2)) is issued.

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

DiSEqC mode

eg Horizontal with 22kHz on:

Reg 22 = 65 (41hex)

Signal input - Search mode

eg for SYS_CLK=60MHz and

30 to 20 MBaud range:

Reg 23 = 136 (88hex)

Reg 24 = 0

Viterbi code rate search

eg V_IQ swap not set:

Reg 25 = 47 (2Fhex)

GO

Re-acquire signal

Reg 27 = 1

Figure 16. Channel change sequence with search mode, DVB mode.