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Theory of Operation: User Interface
3.5
User Interface
The User Interface consists of 2 main sections, the LCD display as well as user activated menu
buttons and frequency and volume knob.
3.5.1
LCD Display
The LCD of XTL1500 provides 1 line / 8 alphanumeric characters with 1 upper row of 8 soft icons
and 4 programmable soft menus on the bottom. The LCD is backlit with 4 LEDs. Solomon SSD1805
Driver is used to drive the LCD and interfaces to the OMAP processor through 8 parallel SoSSI lines.
The LCD operates off 2.8V while the LEDs are powered by SW_B+.
3.5.2
Keypad, Volume and Frequency Knob
Five keypad buttons configured as column/row matrix is used in XTL1500. One button is default
programmed as emergency while the other four activates the user programmed soft menus.
The volume knob provides a linear increase in volume and is converted to digital signals through the
A/D converter (U4202) which connects through SPI to OMAP IC.
The frequency knob is configured to provide a standard 48 frequency channel selection with a
maximum of 256 channel selection (software dependent) and uses 4 GPIs for frequency selection.
3.6
GCAI Accessory Interface
GCAI or Global Core Accessory Interface is the new Motorola accessory interface standard that
provides the user the ability of retaining GCAI compatible accessories when migrating to new radio
platforms. XTL1500 is one of the first Motorola products to implement this standard and is GCAI
Class 0 compliant. The accessory interface port (J7000) incorporates USB Host and Client, 2-wire
RS232 UART transmission, GPIOs and One Wire device detect capability.
Note that the GCAI accessory connector, J7000 resides on a small GCAI board
Schematics, Component Location Diagrams, and Parts
control head board. They are connected together via a 12- wire bridge cable.
USB_VBUS
USB LINES
UART LINES
GPIO 1 & 2
TO
OMAP
GPIO_0
GPIO_3
GPIO_4
ONE_WIRE
MIC_HI
TO
BRICK
RX_AUDIO
6815854H01-A
USB CURRENT
LIMITER
UART/GPIO
MUX
ATTiny13
Level
Shifters
OP_AMP
Figure 3-5. GCAI Block Diagram
Lists") due to limited space on the main
USB_VBUS
UART/USB
USB/UART/
GPIO
MUX
GPIO_O [PWR ON]
GPIO_3 [PTT]
GPIO_4 [HOOK]
ONE_WIRE
MIC_HI
RX_AUDIO
3-7
("Chapter 7.
June 15, 2005
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