CTCSS Signalling Processor
FX818
DETECT/
PREDICTIVE
Function
Bit 3
0
1
DETECT mode
PREDICTIVE mode
If the CTCSS FAST DETECT ENABLE bit is "0" then both modes are
deselected.
(Bits 2, 1 and 0)
Reserved for future use. These should be set to "0".
GENERAL CONTROL Register (Hex address $88)
This register is used to control the functions of the device as described below:
BPF ENABLE
(Bit 7)
When this bit is "1" the audio band-pass filter is enabled. When this bit is "0" the
audio band-pass filter is disabled (powersaved).
BPF UN-MUTE
(Bit 6)
When this bit is "1" the audio band-pass filter output is switched to the RX
AUDIO OUT pin. When this bit is "0" the output of the filter is disconnected from
RX AUDIO OUT, which is then in a high impedance state.
This control, along with BPF ENABLE, allows the filter to power up and settle
internally before switching the output on, to avoid clicks when coming out of
powersave.
BPF 6dB PAD
(Bit 5)
When this bit is "1" a 6dB attenuator is inserted into the output of the audio
band-pass filter. When this bit is "0" the output of the audio band-pass filter is
not attenuated.
(Bits 4, 3 and 2)
Reserved for future use. These should be set to "0".
TIMER ENABLE
(Bit 1)
When this bit goes to a "1" the general purpose timer is restarted and its internal
register is re-loaded from the value specified in the GENERAL PURPOSE
TIMER Register (Hex address $8B). It will then count down from the count held
in its internal register. When this bit is "0" the count down is disabled and the
last pre-programmed value is retained in the timer's internal register.
TIMER RE-CYCLE
(Bit 0)
When this bit is "1" the general purpose timer will re-load its internal register from
the value specified in the GENERAL PURPOSE TIMER Register (Hex Address
$8B) when the count in the internal register reaches zero (i.e. the timeout has
expired). It then restarts the count down, so that the timer continuously cycles.
When this bit is "0" the general purpose timer will stop when the count in the
internal register reaches zero (i.e. the timeout has expired). The timer can only
be restarted by reloading a value into the GENERAL PURPOSE TIMER Register
(Hex address $8B).
If this bit is switched from "1" to "0" whilst the timer is enabled then the timer will
complete the present count before stopping.
ã 1997 Consumer Microcircuits Limited
10
D/818/4
CMLMICRO [ CML MICROCIRCUITS ]
