FX828 Datasheet, PDF (16/34 Pages) CML Microcircuits – CTCSS/DCS/SELCALL Processor

CTCSS/DCS/SELCALL Processor
FX828
A = ^{fXTAL (Hz)}
4 x f_TONE (Hz)
where A is the binary number programmed into the 13 bits.
When Bit 7 (in the first 8 bits) is set to "1" the tone output is set at V_BIAS or NOTONE without regard to the
number "A" programmed. When Bit 7 is "0" the programmed tone is set on the output. Programming the
bits 0 to 12 to "0" puts the Tx into powersave and the output goes to V_BIAS. Powersave is also achieved
by disabling the SELCALL Tx.
8-bit Read Only Registers
HEX
ADDRESS/
COMMAND
REGISTER
NAME
BIT 7
(D7)
SELCALL &
DCS
$81
SUB-AUDIO
DECODE/
STATUS
NO DECODE
$8F
IRQ FLAG
0
BIT 6
(D6)
BIT 5
(D5)
CTCSS
FAST
0
TONE
GP TIMER COMP
IRQ
0 to 1
FLAG IRQ FLAG
BIT 4
(D4)
TONE
DECODE
COMP
1 to 0
IRQ FLAG
BIT 3
(D3)
MSB
BIT 3
TONE
IRQ
FLAG
BIT 2
(D2)
BIT 1
(D1)
RX TONE
BIT 2
CTCSS FAST
IRQ
FLAG
BIT 1
0
BIT 0
(D0)
LSB
BIT 0
DCS
IRQ
FLAG
Read Only Register Description
SELCALL and SUB-AUDIO STATUS Register (Hex address $81)
This register is used to indicate the status of the device as described below:
DCS DECODE/NO
DECODE
(Bit 7)
When the DCS decoder is enabled this bit is continuously updated with the
result. A "1" indicates a successful decode (with 3 or less errors). A "0"
indicates a failure to decode.
CTCSS FAST TONE
(Bit 6)
When Bit 5 in the SIGNALLING CONTROL Register and Bit 3 in the
SIGNALLING SET-UP Register are set to enable FAST CTCSS DETECT mode,
this bit will be set to "1" if a periodic tone is detected. If no periodic tone is
detected this bit will be "0".
When bits 5 and 3 are set to enable FAST CTCSS PREDICTIVE mode, this bit
will be set to "1" if a periodic tone that matches the frequency programmed in
the CTCSS TX/FAST RX FREQUENCY Register is detected. If no match is
found this bit will be "0".
When Bit 5 in the SIGNALLING CONTROL Register is set to "0" this bit will be
"0".
(Bit 5)
Reserved for future use. This will be set to "0" but should be ignored by the
user's software.
TONE DECODE
(Bit 4)
This bit indicates the status of the tone decoder. A "1" indicates a tone has
been detected (TONE DECODE) and a "0" indicates the loss of the tone
(NOTONE).
© 2009 CML Microsystems Plc
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