SI2107-D-FM Silicon Laboratories Inc, SI2107-D-FM Datasheet - Page 32

• Manufacturer Part Number: SI2107-D-FM
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2107-D-FM

• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Lead Free Status / Rohs Status: Compliant

Si2107/08/09/10
6.7. LNB Signaling Controller
All device versions provide LNB signaling capability.
The device supports several LNB signaling methods
including dc voltage selection, continuous tone, tone
burst,
messaging. A description of each method follows.
6.7.1. DC Voltage Selection
A constant dc voltage of 18 or 13 V is typically used to
switch the LNB between horizontal and vertical polarity
or clockwise and counterclockwise polarization. The
LNBV bit is used to select the desired voltage.
When an external LNB supply regulator is used, the
DCS pin is driven high or low depending on the
selection of high or low voltage.
6.7.2. Tone Generation
Tone-related information is communicated to external
devices via the TGEN pin. The tone format select bit,
TFS, specifies whether the output of TGEN is an
internally-generated tone or a tone envelope. The
frequency of the internal tone generator is governed by
the following equation:
Frequencies between 20 and 24 kHz are supported.
The default value of TFQ results in a nominal tone
frequency of 22 kHz. When tone envelope output is
selected, a high signal on TGEN corresponds to "tone
on" while a low signal corresponds to "tone off." When
operating in the “Manual LNB messaging mode”, the TT
bit directly controls the output of the tone or tone
envelope.
6.7.2.1. Continuous Tone
A continuous tone is typically used to select between
the high and low band of an incoming satellite signal.
The LNBCT bit can be set to one to generate a
continuous tone.
6.7.2.2. Tone Burst
The tone burst signaling method can be used to
facilitate the control of a simple two-way switch. Two
types of tone burst are available, as shown in Figure 17.
An unmodulated tone burst persists for 12.5 ms. A
modulated tone burst lasts for the same duration but
consists of a sequence of nine 0.5 ms pulses and 1 ms
gaps. Tone burst selection is controlled via the LNBB
bit. The tone burst command can optionally be disabled
to support systems that do not use tone burst signaling
by setting the burst disable bit, BRST_DS, to one. This
disables the tone/burst generation as part of the
DiSEqC signaling sequence when the device uses
32
DiSEqC
f
tone
=
--------------------------------------------------------- - MHz
[
1.x-
32
×
(
TFQ 7:0
and
100
[
DiSEqC
]
+
1
)
]
2.x-compliant
Rev. 1.0
“Automatic LNB messaging mode” as described below.
6.7.3. DiSEqC™
The DiSEqC signaling method extends the functionality
of the legacy 22 kHz tone by superimposing a
command protocol and adding an optional return
channel. A DiSEqC command normally consists of a
framing byte, an address byte, a command byte, and,
optionally, one or more data bytes. This format is
illustrated in Figure 18.
The length of a message is specified by MSGL. When
the message length is set to one byte, the message is
modulated using tone burst modulation. When the
message length is set to two or more bytes, the
message
modulation, and the odd parity bit is automatically
added. The DiSEqC modulation scheme is illustrated in
Figure 19.
6.7.3.1. DiSEqC 1.x One-Way Communication
Messages are programmed directly into the device
using a message FIFO that consists of six byte wide
registers, FIFO1–6. The messages must be written in a
first-in-first-out manner such that the first byte of a
message is stored in FIFO1; the second byte is stored
in FIFO2, and so on. If messages are longer than six
bytes, the device asserts the FIFO empty indicator, FE,
as soon as the sixth byte has been read. The LNB
control module then takes its next byte from FIFO1 and
Envelope
Envelope
FRAMING
Tone
Tone
Figure 19. DiSEqC Compliant Modulation
Figure 18. DiSEqC Message Format
Figure 17. Tone Burst Modulation
1.0 ms
'0' Data Bit
is
P
modulated
ADDRESS
0.5 ms
'0' Tone Burst (Satellite A)
'1' Tone Burst (Satellite B)
P
12.5 ms
using
COMMAND
0.5 ms
'1' Data Bit
DiSEqC-compliant
P
1.0 ms
DATA
P