THEORY OF OPERATION: Digital Section
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The REDCAP performs the following tasks:
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Controls the power up and power down sequence of the unit
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Programs the flash using BDM or SB9600 software
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Transfers DSP code from the flash to DSP SRAM
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Serially communicates with the factory PATS stations using SB9600
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Serially communicates with PCs or Macs using UART
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Communicates with the RF ICs (GCAP II, LV Frac-N, ADDAG, ODCT, and
iZIF)
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Memory maps and accesses flash ROM and SRAM
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Monitors battery voltage and RF power-amplifier temperature
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Controls volume levels and enables beep tones
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Modifies and stores user-selectable ergonomic preferences
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Reads and writes radio-tuning parameters to the codeplug
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Sends and receives commands with the base station through DSP
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Re-channels the LV Frac-N synthesizer during hand-off
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Detects accessories connected to the unit using the Opt Sel lines
Power On/Off Circuitry
The power-on circuitry uses the GCAP II MOBPORTB pin to turn on the unit.
When the ON/OFF pin (J4-17) is held high, the GCAP II turns on. The GCAP
internal low voltage detector provides the initial, active low reset to the RISC
microprocessor (MCU). After the VCC3 arrives at the digital section, the MCU
takes over and drives the reset out line low until its internal PLL locks. At this
point, the MCU begins running the subscriber code. The MCU asserts the CS1
signal to a high level, which goes to the GCAP WDI to keep the voltage regulators
on. If the MCU does not drive this signal high, the unit will not stay powered up.
To turn off the unit, the OEM ON/OFF pin is held low, causing the MOBPORTB
pin of the GCAP II to short to ground. The GCAP II then clears the MOBSENSB
bit, which drives IRQ1 on the MCU and tells the MCU to turn off. The MCU turns
off by driving the WDI line low, which shuts down the voltage regulators in the
GCAP II.To turn off the unit, the ON/OFF key is pressed, causing the /ON pin of
the GCAP II to short to ground. The GCAP II then sets the ONOFFSNS bit,
which drives IRQ1 on the RCE and tells the RCE to turn off. The RCE turns off
by driving the WDI line low, which shuts down the voltage regulators in the
GCAP II.