Motorola APX 1000 Detailed Service Manual page 745

Theory of Operation
: Controller
Prior to the LCD interpreting any commands, the correct display power-up sequence must be
initiated. First the V_EXT_1.85 (1.875 V) and V_2.775D (2.775 V) supplies must be at 90% or above
threshold and stable for 10us, and then reset can be asserted high. After OMAP de-asserts the reset
out signal (OMAP_RESET) the SLPOUT command can be sent. Now configuration commands are
ready to be sent to the LCD module.
The QVGA LCD module is only intended to operate up to +80°C due to ghosting effects. Therefore
software will shut off the display and backlight if the +80°C limit is reached. The display and backlight
will remain off until temperature drops below +75°C. The temperature sensor, U6401, for the display
cut-off is input into MAKO A/D Channel 3, pin M14.
For enhanced display readability, the default backlight is set to a dim state while the radio is in
Standby mode; however, the backlight turns to full brightness through a button press, call receive,
emergency call, and other status indicators. See
backlight operation.
3.2.6.3 Intelligent Lighting
The APX 1000 radio is equipped with numerous LEDs to provide intelligent lighting features. The
Main board consists of a backlighting driver, which illuminate all the LEDs throughout the radio, as
shown in Figure
color display, Tricolor TX/RX indicator, status indicator and white keypad backlights. The driver are
controlled through OMAPs I2C interface (SCL and SDA). The I2C communication protocol allows the
OMAP chip to enable, disable, and control the brightness of each LED. The driver uses PWM output
to control the dimming modes operation. A reset line issued by OMAP, OMAP_RESET, can be used
to reset the driver. Some of the intelligent lighting color schemes are shown in
and LEDs are powered by Switcher 5 (V_SW_5).
3-30. The backlighting driver, U2201, provides white illumination to the main QVGA
Table 3-6. Color Schemes
Default
Out of Range
Low Battery
Emergency
Call Received
Call Paged
Section 3.2.6.3: "Intelligent Lighting"
Color
White
Red
Red
Amber
Green
Green
3-41
for the display
Table 3-6. The driver