Controls And Control Top Flex - Motorola ASTRO XTS 5000 Detailed Service Manual

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4.3.4.6 Controls and Control Top Flex

The housing assembly top controls include an on/off switch/volume control (S1), a 16-position mode-
select switch with programmable two-position concentric switch (U1), a programmable three-position
(A,B,C) toggle switch (S2), and a programmable top (orange) button (SW3). The side controls
include three programmable, momentary, push button switches (side button 1 [SB2], side button 2
[SB3], and top side button [SB1]) and a PTT switch (SW2). These components are connected
through a flex circuit to the controller at J101 (see
radio's internal speaker and internal microphone.
UNSW_B+ is routed through switch S1 to provide the B+SENSE signal, which is used to activate the
SW_B+ and GCAP_B+ voltages that, in turn, power up the radio. Volume control is also provided by
S1, which contains a potentiometer biased between 3 volts and ground. The VOL signal is a voltage
level between 3 volts and ground, depending on the position of the rotary knob. The VOL signal is
fed to buffer U507 pin 3, and then the output of the buffer is voltage-divided down to 2.5 volts before
the signal goes to the GCAP II IC AD5 pin. The Patriot IC reads the GCAP II IC A/D value through
the SPI bus, and from this reading, the Patriot IC DSP adjusts the speaker volume.
Switch S2 is the three-position, programmable, toggle switch typically used for expanded zone/
channel selection. The switch can output the following voltages: 0 volts, 1.5 volts, and 3.0 volts
(measurable at R231). The switch is connected to the GCAP II IC AD1 input pin through the voltage
divider network of R519 and R523. The Patriot IC reads the A/D value through the SPI bus, and it
uses that reading to determine the position of the toggle switch.
The programmable top (orange) button SW3 is typically used for emergency. This button, along with
programmable side buttons SB1 through SB3, is connected to a resistor divider network, biased
between 3 volts and ground. This network, made up of R1, R2, and R3, provides a voltage level,
controlled by which button is pressed, to pin 3 of buffer U504. The output of the buffer is voltage-
divided down to 2.5 volts before the signal goes to the GCAP II IC AD0 pin. The Patriot IC reads the
GCAP II IC A/D value through the SPI bus, and it uses that data to determine which button was
pressed.
LED D1 is the TX/RX indicator. LEDs D2 through D6 are used for backlighting the frequency knob.
U1 is a binary-coded switch. The output pins from U1, which are connected to GPIO pins on the
Patriot IC, provide a four-bit binary word (signals RTA0, RTA1, RTA2, and RTA3) to the MCU,
indicating to which of the 16 positions the rotary is set. This switch provides an additional output,
TG2 that is typically used for coded or clear mode selection. It is an input to the Patriot IC
TOUT8_PD4 GPIO pin. Selecting clear mode pulls this signal to a logic low, and it can be monitored
from R234.
April 15, 2002
Detailed Theory of Operation
Figure 4-6). The assembly also contains the
: VOCON Board
68P81094C31-O