3-48 Theory of Operation: Controller
3.2.6.3 Intelligent Lighting
The APX 5000/APX 6000/APX 6000XE/SRX 2200 radio is equipped with numerous LEDs to provide
intelligent lighting features. The VOCON board contains 2 lighting controller devices, which
illuminate all the LEDs throughout the radio, as shown in Figure 3-34. The main lighting controller,
U2204, provides white illumination to the main QVGA color display, and white keypad backlights.
The secondary lighting controller, U2201, generates illumination for the top display backlight and TX/
RX indicator lamp. Both lighting controller devices are controlled through OMAPs I2C interface (SCL
and SDA). Some of the intelligent lighting color schemes are shown in Table 3-8.
3.2.6.3.1 Main Lighting Controller
The boost lighting controller, U2204, provides backlight functionality for the main color QVGA
display, and the white backlight on the keypad. Switcher 3.6 (V_SW_3.60) is used as main input
voltage for the controller, while external 1.85 (V_EXT_1.85) is used for IO voltage. The controller
communicates with the OMAP via standard I2C communication protocol. This communication allows
the OMAP chip to enable, disable, and control the brightness of each LED. A reset line issued by
OMAP, OMAP_RESET, can be used to set the device in reset. The charge pump capability of the
lighting controller is currently not used. Refer to Figure 3-34.
The QVGA display has 3 LEDs powered by the external 3.6 regulator, V_SW_3.6. The cathode
output (negative) of each LED is fed back into the LED driver to control the current thus controlling
the brightness of the LEDs. The front display backlights are controlled by bank B of the LED
controller.
The keypad backlighting uses 4 white LEDs for illumination. The keypad backlighting operates
similar to the main QVGA display LEDs. The LEDs are powered by the external 3.6 regulator,
V_SW_3.6. The cathode output (negative) of the LEDs is fed back into bank A of the LED driver to
control the current thus controlling the brightness of the LEDs.
Table 3-8. Color Schemes
Color
Default White
Out of Range Red
Low Battery Red
Emergency Amber
Call Received Green
Call Paged Green
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