CTCSS Signalling Processor
FX818
CTCSS RX TONE
(Bits 3, 2, 1 and 0)
These four bits hold a Hex number from $0 to $F. Numbers $0 to $E represent
the address of the CTCSS tone decoded according to the tones programmed in
the CTCSS RX PROGRAM Register, $84. The Hex number $F indicates the
presence of any tone that is not described by CTCSS DECODER BANDWIDTH
(Bits 7, 6, 5 and 4, SUB-AUDIO SET-UP Register, $82) and CTCSS
FREQUENCY (Bits 11 - 0, CTCSS RX PROGRAM Register, $84).
IRQ FLAG Register (Hex address $8F)
This register is used to indicate when the device requires attention as below:
(Bits 7, 5, 4, 1 and 0)
Reserved for future use. These will be set to "0" but should be ignored by user's
software.
GPT IRQ FLAG
(Bit 6)
When the general purpose timer has reached zero in its internal register, this bit
will be set to "1" to indicate the timeout has expired. This bit is cleared to "0" by a
read of the IRQ FLAG Register (Hex address $8F).
CTCSS IRQ FLAG
(Bit 3)
When CTCSS RX DECODE (Bit 4, SUB-AUDIO STATUS Register, $81)
changes state this bit will be set to "1".
This bit is cleared to "0" by a read of the IRQ FLAG Register (Hex address $8F).
CTCSS FAST IRQ
FLAG
When CTCSS FAST TONE (Bit 6, SUB-AUDIO STATUS Register, $81) changes
state this bit will be set to "1".
(Bit 2)
This bit is cleared to "0" by a read of the IRQ FLAG Register (Hex address $8F).
ã 1997 Consumer Microcircuits Limited
15
D/818/4
CMLMICRO [ CML MICROCIRCUITS ]
