Motorola SSETM 5000 - Manual (Page 53)

6881094C12-A November 11, 2004
Theory of Operation: VOCON Board 2-31
Table 2-11 outlines their functions as defined at the universal connector.
2.5.3 Display Module
NOTE: The VOCON kit is only compatible with the 7285419E01 display module.
The 7285419E01 display module is an integral 112 by 32 pixel bit-mapped, liquid-crystal display
(LCD) module. The display module is connected to the VOCON board through flex connector J301.
It uses chip-on-film technology and is not field repairable.
The display module is controlled by the dual-core processor MCU core, which programs the display
through the serial peripheral interface (SPI) bus. The SPI bus programs the display through the
serial data line (pin 10), serial clock line (pin 7), chip select line (pin 3), and register select line (pin 6)
that is used to select the register to be programmed. The dual-core processor can reset the display
module through pin 2.
The display is supplied with 2.893V GCAP II regulated voltage (B700) to pins 11 and 14. Display
backlighting is controlled by the dual-core processor GPIO line BL_EN signal through components
R140 and Q101. The LEDs on the display module are powered by 5 V going through resistors R704,
R705, and Q700.
2.5.4 Controls and Control Top Flex
The housing assembly top controls include the On/Off/Volume switch (S1), a 16-position Channel
Select switch, and a programmable three-position (A,B,C) toggle switch (S2).
The side controls include three programmable pushbutton switches (top side button [SB1], side
button 1 [SB2], side button 2 [SB3]) and a Push-to-Talk (PTT) switch (SW2). These components are
connected through a flex circuit to the controller at J707.
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 V2 regulated voltage and ground. The VOL
signal is a voltage level between V2 regulated voltage and ground, depending on the position of the
knob. The VOL signal is fed to buffer U506 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 dual-core processor reads
the GCAP II IC A/D value through the SPI bus, and from this reading, the dual-core processor DSP
adjusts the speaker volume.
Switch S2 is the three-position, programmable, toggle switch typically used for zone selection. The
switch can output the following voltages: 0 volts, half of the V2 regulated voltage, or V2 regulated
voltage (measurable at R523). The switch is connected to the GCAP II IC AD1 input pin through the
voltage divider network of R519 and R523. The dual-core processor reads the A/D value through the
SPI bus, and it uses that reading to determine the position of the toggle switch.
Table 2-11. Option Select Functions
Function
Option Select
Voltage
External PTT < 0.30
External Audio & Internal Antenna 1.25
External Audio & External Antenna 2.50
No Accessory Attached >4.40