6816985H01-F February 14, 2012
UHF1 Detailed Theories of Operation: VOCON Functional Blocks 4.2-15
4.2.6.3.4 The Option Board
The Option Board consists of the "keypad module" and the "display module" for models II and III of
the XTS 2500/XTS 2500
I/XTS 2000/ATS 3000 radio.
4.2.6.3.4.1 Display Module
An optional integral 96 pixels by 64 pixels LCD display module is available with either a 3 x 2 keypad
with a navigational button (Model II radios), or 3 x 6 keypad with a navigational button (Model III
radios). This unit is not considered field-repairable. The display module is connected to the VOCON
section through the flex connector (J900).
The display is controlled by the Patriot's MCU core. The MCU core programs the display through the
following:
• EIM data lines D0 – D7 (pins 9 through 16, respectively),
• the display chip select line (pin 5),
• the EIM "write only" line (pin 8), and
• the EIM address 0 line (pin 7).
The EIM address 0 is used to select the register to be programmed. The Patriot may reset the
display module through pin 6. The display is supplied with 1.8 volts (C901) to pin 17and 3 volts
(C902) to pin 18.
The Patriot GPIO BL_EN controls the display backlighting; that signal goes to pin 43 of the J601
connector (on the radio board), and the corresponding pin 3 of the J901 connector (on the Option
board).
Pin 4 of the J601 connector (on the radio board), and the corresponding pin 42 on the J901
connector (on the Option board) is supplied with 7.5 volts. The 7.5 volts is used to power the LEDs
on the display module.
Pin 2 of the J601 connector (on the radio board), and the corresponding pin 44 on the J901
connector (on the Option board), is supplied with the V2 regulated voltage. The V2 regulated voltage
is used to power DISPLAY_VCC.
Pin 1 of the J601 connector (on the radio board), and the corresponding pin 45 on the J901
connector (on the Option board), is supplied with 1.8 volts. The 1.8 volts is used to power
DISPLAY_VDD.
4.2.6.3.4.2 Keypad Module
The keypad module is connected to the main board through flex connector (J601) on the radio board
schematic and J901 on the Option board schematic. The keypad is read though a row-and-column
matrix made up of ROW0, ROW1, ROW2, ROW3, ROW4, ROW5, ROW6 and COL0, COL1, and
COL2. This totals 18 keys on the keypad. When a key is pressed, a row and a column are connected
to one another.
The Patriot determines a key press by a scanning algorithm. Each column line is configured as an
open drain output and pulled low. The Patriot then scans the row pins (each row pin has an internal
pull up resistor). If a row signal is read low, then the Patriot determines that a key was pressed. If
none of the row signal lines are low, then another column line is pulled low and the row scanning
routine occurs.
The Patriot GPIO BL_EN controls the keypad backlighting; that signal goes to pin 43 of the J601
connector (on the radio board), and the corresponding pin 3 of the J901 connector (on the Option
board). Pin 42 is supplied with 7.5 volts, which is used to power the LEDs on the keypad module.
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