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The PM general housekeeping functions include an analog multiplexer
that has several internal and external connections. The internal
connections are used to monitor on-chip functions, such as the
temperature sensor and reference voltage. Six external connections are
hardwired to access input power nodes, such as VCHG, VBAT, etc.
And finally, two multipurpose pins can be configured as analog inputs
and routed to the multiplexer through a switch matrix. These are
available to monitor system parameters such as temperatures, battery
ID, or transmit power level. The multiplexer output signal's offset and
gain is adjusted, then buffered and routed to the analog/RF circuits for
analog-to-digital conversion.
Various oscillator, clock, and counter circuits are provided to initialize
and maintain valid pulse waveforms and measure time intervals for
higher-level handset functions. A dedicated controller manages the
TCXO warm-up and signal buffering, and key parameters are monitored
to protect against detrimental conditions. A new and improved search
and acquisition algorithm eliminates the need for a VCTCXO (typically
±2.5 ppm) allowing a less expensive 19.2 MHz crystal (typically ±12
ppm, max load capacitance, 7 pF) to be used.
Handset-level user interfaces are also supported. The PM block
includes two backlight or LED drivers with brightness (current) control
that are intended for keypad and LCD lighting. A vibration motor driver
alerts handset users of incoming calls, and a speaker driver with volume
control can be used for audio alerts or speakerphone and melody ringer
applications.
PM circuit interfaces include a bus used by the baseband circuits to
control and status the PM functions. This bus is supplemented by an
interrupt manager for time-critical information. Another dedicated
interface circuit monitors multiple trigger events and controls the powe
on/poweroff sequences. A universal serial bus (USB) transceiver is
included for interfacing the baseband circuits to computers as a USB
1.1 peripheral.
4.2.2.4 LCD
We use 320*240 dot matrix 262k color TFT LCD display module, with
touch panel support.
4.2.2.5 Camera Module
We use 2.0 mega camera module with OV CMOS sensor.