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3 ST7LNB0 FUNCTIONAL DESCRIPTION

3.1 ST7LNB0 Configuration

Unlike the original slave microcontroller described

in the “Eutelsat DiSEqC slave microcontroller ver-

sion 1.0” the ST7LNB0 does not scan the control

pins in order to determine the slave configuration,

instead all configuration parameters must be pro-

grammed for each specific application, an Option

List (Section 8) must be filled-in in order to pro-

gram the necessary options at the manufacturing

stage.

The slave configuration parameters are the follow-

ing:

– The DiSEqC™ slave address e.g.: 11h for an

LNB, 15h for a switcher.

– The Local oscillator frequency table entry

numbers.

– The DiSEqC™ configuration byte (refer to

DiSEqC slave microcontroller document page

15)

– The output mode (see next paragraph)

– 22 kHz tone use in backwards compatible

mode (SB/SA or Hi/Lo switching)

– Standby pin use.

3.2 ST7LNB0 Switching Output Modes

The ST7LNB0 has 8 pins (OP1 to OP 8) available

to provide ‘TTL’ logic levels to operate switches to

select various signal conditions and sources (e.g.

horizontal polarization, satellite position).

As listed in Table 2 the committed output port is

composed of OP1 to OP4 and the uncommitted

output port is composed of OP5 to OP8.

Depending on the application hardware, the

switching control pins OP1 to OP8 may be operat-

ed differently. Three possible output modes can be

configured:

Single polarity output mode. In this mode each

pin can be controlled individually as described in

the following table:

Table 3. Single polarity output mode

Decoded output mode. This mode offers the pos-

sibility to demultiplex three adjacent committed or

uncommitted control lines (e.g Hi/Lo, SB/SA and

SOB/A) in order to have a 1 of 8 demux on the out-

put port OP1 to OP8. (for more details refer to DiS-

EqC™ slave microcontroller specification docu-

ment page 10).

It is also possible to have a 1 of 4 demux by decod-

ing only 2 control lines e.g. SB/SA and SO B/A for

controlling a 1 of 4 switcher for example.

Complementary output mode. In this mode the

state of the uncommitted switching outport pins is

the complementary of the state of the committed

output ports pins (for more details refer to DiSE-

qC™ slave microcontroller document page 14).

Pin Number Function Name

Function

Description

OP4

SO B/A

OP3

SB/SA

OP2

Hor/Ver

OP1

Hi/Lo

OP5

SW5

OP6

SW6

OP7

SW7

OP8

SW8

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