54
TMAA02-02 DTMF Microphone
TM8100/TM8200 Accessories Manual
© Tait Electronics Limited
August 2005
Installing the
Microphone Clip
Install the microphone clip in the most convenient location for the radio
user. It must be within easy reach of the user, but in such a position that the
microphone PTT key cannot be inadvertently activated or jammed on.
Connect the microphone clip to the negative supply if hookswitch
operation is required.
5.2
Adjustment
Remove the DTMF microphone back cover and set the DTMF tone level
to approximately 60% deviation (± 3 kHz for wide bandwidth radios and
± 1.5 kHz for narrow bandwidth radios).
5.3
Radio Programming
The following table shows the settings required for CH_GPIO1 in the
Programmable I/O form of the programming application. This setting
means that when a key is pressed on the microphone, the DTMF tones are
fed into the radio’s speaker at a reduced volume, giving the radio user
confidence that the tones are being transmitted. Refer to the online help of
the programming application for more information.
5.4
Interface Specification
The following table and diagram summarizes the signals used for the DTMF
microphone on the radio’s microphone connector and shows the interface
between the DTMF microphone and the radio.
Table 5.1
DTMF microphone settings in the Programmable I/O form, Digital tab
Pin
Direction
Label
Action
Active
Debounce
Signal State
Mirrored To
CH_GPIO1 Input
None
Send Mic Audio
To Spkr
High
None
None
None
Table 5.2
DTMF microphone connector—pins and signals
Pin
Signal
Colour
Description
1
—
—
not connected
2
13V8_SW
red
power supply (switched)
3
—
yellow
not connected
4
MIC_PTT
black
PTT and hookswitch
5
MIC_AUD
white
audio from the microphone
6
AGND
blue
analogue ground
7
—
—
not connected
8
MIC_GPIO1
green
mute out
