Micro Digital Satellite Receiver Instrukcja Użytkownika Pobierz pdf (Strona 3)

AN2677/D

DiSEqC Introduction

Digital Satellite Equipment Control (DiSEqC ) using MC68HC908QT/QY 3

Application

Characteristics

This application using the MC68HC908QT4 as the DiSEqC slave has the

following characteristics:

• Two LNBs will be controlled (default is satellite A).

• Because the MC68HC908QT/QY series is compatible with non-DiSEqC

control, it is possible to use the earlier satellite receivers with voltage

(13 V to 18 V), tone (22 kHz present or not), and tone-burst control

capabilities.

• The switch (MC68HC908QT4 plus additional components)

automatically detects whether the tone-burst protocol or DiSEqC is

used. After power-up or reset, the ODU can recognize tone-burst or

DiSEqC control; after DiSEqC control is received, tone-burst control is

blocked.

• DiSEqC level 1.0 will be used.

• The following bus commands are recognized by the DiSEqC slave:

– Framing byte:

$E0, $E1

– Address byte:

$00 — Any device (master to all devices)

$10 — Any LNB, switcher or SMATV

– Command byte:

$00 — Reset DiSEqC microcontroller (MC68HC908QT/QY)

$02 — Switch peripheral power supply OFF

$03 — Switch peripheral power supply ON

$22 — Select satellite position A

$23 — Select switch option A (e.g., position A/B)

$26 — Select satellite position B

$27 — Select switch option B (e.g., position C/D)

$38 — Write to port group 0

– Port group 0 data (first data byte):

$F8, ($FA, $FC, $FE) — Switch to satellite A

$F0, ($F2, $F4, $F6) — Switch to satellite B

Because this application uses level 1.0, basic DiSEqC bus commands and the

low pin count MC68HC908QT4 are used. Other commands may be added for

possible new functions. The MC68HC908QT4 can control a maximum of four

LNB for DiSEqC level 1.0 commands. In this case, only two outputs are used,

and two are left free. It is possible to implement this software for MCU

MC68HC908QY4 to obtain a higher pin count and more control capability to

satisfy the DiSEqC level 1.1 or level 1.2 requirements.

The MCU uses the FLASH programmed value for the TRIM register. This value

ensures good accuracy of the bus frequency.

Freescale Semiconductor, I

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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Freescale Semiconductor, I 1

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