Controlling Protocol ......
“Write to Control Register” – A/C 70H (78H), followed by 1 byte of Command Data.
Table 3 (below) shows the configurations available to the FX805. Bits 5, 6 and 7 are used together to Enable and Powersave
circuit sections as required.
Control Bits
Setting
Transmitted First
Functions Enabled
MSB
7
Functions Powersaved
6
5
CTCSS Decoder
NRZ Decoder and Both Encoders
CTCSS Decoder and Both Encoders
All Decoders
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
NRZ Decoder
CTCSS Encoder
NRZ Encoder
All Decoders
CTCSS Encoder and Decoder
NRZ Encoder and CTCSS Decoder
NRZ Decoder and CTCSS Decoder
NRZ Decoder
NRZ Encoder and Decoder
None
All Encoders
All Encoders (except Tx Sub-Audio LPF)
and CTCSS Decoder
4
1
Enable Audio Output – Used with Bit 3
Disable Audio Output – Output to VBIAS
0
3
1
Enable Sub-Audio Bandstop Filter (Audio Signal Path)
By-pass Sub-Audio Bandstop Filter
0
2
1
Enable All FX805 Interrupts
Disable All FX805 Interrupts
0
1
1
Set Rx Lowpass Filter bandwidth to 180Hz – For low CTCSS Tones or NRZ Data
Set Rx Lowpass Filter bandwidth to 260Hz
0
0
1
All Encoders and Decoders Powersaved (Powersave All)
0
All Encoders and Decoders Enabled unless individually Powersaved
Table 3 Control Register
General Reset
Glossary of Abbreviations
Upon Power-Up the “bits” in the FX805 registers will be
random (either “0” or “1”). A General Reset Command (01H)
will be required to “reset” all microcircuits on the
Below is a list of abbreviations used within this Data Sheet.
CDCS
CTCSS
DPL
Continuous Digitally Coded Squelch
Continuous Tone Controlled Squelch
Digital Private Line
“C-BUS,” and has the following effect upon the FX805.
Control Register
Status Register
NOTONE Timer
Set as 00H
Set as 00H
Discharged
LTR
Logic Trunked Radio
NRZ
Non-Return-to-Zero data levels
Filter cut-off frequency
Warning – The following FX805 register configurations are
not affected by a General Reset command:
CTCSS Rx Frequency
fCO
fCTCSS IN
Sub-Audio Rx frequency
CTCSS Tx Frequency/NRZ Baud Rate Register
NRZ Rx Data Register
NRZ Tx Data Register
fCTCSS OUT
fTONE
Sub-Audio Tx frequency
Tone frequency
Gain-Set Register
fXTAL
Xtal/clock frequency
NRZ Rx baud rate
Note that setting the Control Register in this way (General
Reset) will set the FX805 to the CTCSS Decode mode and
overwrite a “Powersave All” instruction.
It should also be considered that a General Reset
command will reset ALL DBS 800 microcircuits operating on
the “C-BUS.”
RNRZ Rx
RNRZ Tx
SINPUT
NRZ Tx baud rate
Audio input signal
7
CMLMICRO [ CML MICROCIRCUITS ]
