CMX808AP4 View Datasheet(PDF) - MX-COM Inc
Part Name
Description
MFG CO.
'CMX808AP4' PDF : 22 Pages View PDF
Family Radio Service CTCSS Processor
12
4.1.3 Read Only Register Description
CMX808A Preliminary Information
HEX
REGISTER BIT 7
ADDRESS/COMMAND NAME
(D7)
$81
SUB-AUDIO
STATUS
0
BIT 6
(D6)
0
BIT 5
(D5)
0
BIT 4
(D4)
0
BIT 3
(D3)
TONE
DECODE
BIT 2 BIT 1 BIT 0
(D2) (D1) (D0)
CTCSS RX TONE
MSB
LSB
BIT 2 BIT 1 BIT 0
Table 10: 8-bit Read Only Registers
4.1.3.1 SUB-AUDIO STATUS Register (Hex address $81)
Reading the SUB-AUDIO STATUS register clears the interrupt ( IRQ ).
This register is used to indicate the status of the device as described below:
(Bits 7, 6, 5 and 4)
TONE DECODE
(Bit 3)
CTCSS RX TONE
(Bits 2, 1 and 0)
Reserved for future use. These will be set to "0" but should be ignored by user's
software.
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).
TONE DECODE means that a tone has been decoded and its characteristics are
defined by the bandwidth (see SUB-AUDIO CONTROL register $80, Bits 5, 4, 3 and 2)
and the CTCSS RX TONE number (see SUB-AUDIO STATUS register $81, Bits 2, 1
and 0).
When Bit 6 in the SUB-AUDIO CONTROL register $80 is set to "0" the TONE DECODE
Bit 3 will be set to "0".
Identification of a valid tone which is not in the pre-programmed list of up to 7 tones will
cause the decoder to move to the TONE DECODE state with the RX TONE address of
"111" in Bits 2, 1 and 0; indicating a valid but unrecognized tone. Loss of tone will cause
the NOTONE timer to be started. If loss of tone continues for the duration of the time-
out period, then the decoder will move to NOTONE state and the identification of pre-
programmed tones will start again. The time-out period is not user adjustable.
These three bits hold a Hex number. Numbers $0 to $6 represent the address of the
CTCSS tone decoded according to the tones programmed in the CTCSS RX PROGRAM
register $84. The Hex number $7 indicates the presence of any tone that is not
described by CTCSS DECODER BANDWIDTH (Bits 5, 4, 3 and 2 in the SUB-AUDIO
CONTROL register $80) and CTCSS FREQUENCY (Bits 11 to 0 in the CTCSS RX
PROGRAM register $84).
©1999 MX-COM, Inc.
www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054
Doc. # 20480199.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
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