MT312CSLASHCG datasheet(25/90 Pages) ZARLINK

25 / 90 page

Tuner Control

MT312

4.4 Tuner Control Read/Write Registers

4.4.1 General Purpose Port Control. Register 20 (R/W)

B7:

Reserved.

Must be set low.

B6:

2W PAS:

High = 2-wire bus Pass-through.

Low = GPP pin I/O direction set by GPP DIR[2:0].

B5-3:

GPP DIR[2:0]

Any bit set high conﬁgures the corresponding GPP[2:0] pin as output

Any bit set low conﬁgures the corresponding GPP[2:0] pin as input

Mixed use of pins as inputs and outputs is allowed.

If B6 = 1, pass-through mode, then:

GPP DIR[1:0] are ignored,

B2: = Input or output set by GPP DIR[2] - relating to pin 46.

NAME

ADR

Def

hex

GPP CTRL

Reserved

PAS

GPP DIR[2:0]

GPP PIN[2:0]

R/W

Figure 18 - Channel change sequence with

search mode, DVB mode

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 set: AUTO IQ detection

Reg 25 = 175 (AFhex)

Re-aquire signal

Reg 27 = 1

Program MONITOR to read Symbol rate

MON_CTRL Reg 103 = 3

Read Symbol rate from MONITOR registers 123 & 124.

Symbol rate = MONITOR_H/4 + MONITOR_L/1024 MBaud

eg if MONITOR_H = 27 and MONITOR_L = 136

then Symbol rate = 27.53125 MBaud

ie 27.5 MBaud

±0.25%

Read code rate from FEC_STATUS[B6-4] register 6.

eg if FEC_STATUS = 2C hex

signal is locked and the code rate = 3/4

Figure 19 - Results of Symbol rate and code

rate search, DVB or DSS mode

MT312C/CG Datasheet(PDF) 25 Page - Zarlink Semiconductor Inc

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