90 Circuit Descriptions TM9100 Service Manual
© Tait Electronics Limited August 2005
3.9 Control-Head Board
Introduction This section describes the control-head board for the control head with
graphical display.
For a block diagram of the digital circuitry, refer to Figure 3.11.
Most signals (except power on/off, speaker and microphone) to and from
the radio body are processed by a RISC processor, which is implemented on
an FPGA on the control-head board. For more information on the RISC
processor and the FPGA, refer to “Software Architecture” on page 44.
User Interface The control-head board includes the circuitry for the following control
elements:
■ ON/OFF key
■ volume potentiometer
■ main keypad (with four functions keys, two scroll keys and
two selection keys)
■ LCD module (with backlighting and optional heating element)
■ three status LEDs
■ two function key LEDs (for function keys F1 and F4)
■ keypad backlighting LEDs
■ speaker
Connectors The control-head board includes the circuitry for the following connectors:
■ microphone connector (RJ45 socket)
■ control-head connector (18-way MicroMaTch socket)
■ LCD connector (for internal connection of LCD module)
■ speaker connector (2 leads)
■ soldering pads (2 leads) for concealed microphone
■ control-head options connector (for optional circuit board)
Protection circuitry is provided for the microphone connector. For pinouts
of the control-head connector and the microphone connector, refer to
“Connectors” on page 34. For more information on the control-head
options connector, please contact Tait Electronics Limited.
ON/OFF Key When battery power (13.8V) is applied to the radio, a press of the ON/OFF key
will create an active low signal (
CH ON OFF) back to the radio body to initiate
the power-on or power-off sequence. This key-press will also be detected
by the FPGA of the control head through Q611 as an active high signal.
For more information on the start-up process, refer to “Software
Architecture” on page 44.
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