Motorola Sse 5000 6881094c12 A Manual

6881094C12-ANovember 11, 2004
Theory of Operation: VOCON Board2-19
21, and 22. Connections to the external accessory connector, which include serial communication 
data lines, external audio, and option select lines for controlling audio modes, are present at pins 1 
through 13. Switched battery voltage (B+SENSE) is provided on pin 32. Most of the pins at this 
connector have ESD protection devices and components. See Section 2.5.2.3.3: “Universal 
Connector Interface Circuitry” on page 2-29 for more...

November 11, 20046881094C12-A
2-20Theory of Operation: VOCON Board
Microcontroller Unit (MCU)
The MCU portion of the dual-core processor controls receive/transmit frequencies, power levels, 
display, and other radio functions, using either direct logic control or serial communications paths to 
the devices. The microcontrol unit executes a stored program located in the FLASH memory device. 
Data is transferred to and from memory by the microcontrol unit data bus. The memory location from 
which data is...

6881094C12-ANovember 11, 2004
Theory of Operation: VOCON Board2-21
Digital Signal Processor (DSP)
The DSP portion of the dual-core processor performs signaling and voice encoding and decoding, as 
well as audio filtering and volume control. The DSP performs Private-Line/Digital Private-Line (PL/
DPL) encode and alert-tone generation. The DSP transmits pre-emphasis on analog signals, and 
applies a low-pass (splatter) filter to all transmitted signals. The DSP controls squelch, deviation, and 
executes...

November 11, 20046881094C12-A
2-22Theory of Operation: VOCON Board
USB data minus comes from U302 pin 4 and this signal is sent to URXD1 of the dual-core processor.
General-Purpose Input/Output (GPIO) Module
The General-Purpose Input/Output (GPIO) module is shared by the MCU and the DSP. This module 
consists of four 16-pin bi-directional ports and a 15 pin bi-directional port. While some of the pins on 
these ports are being used for other functions (UART, SPI, SAP, BBP, and Interrupt pins), the...

6881094C12-ANovember 11, 2004
Theory of Operation: VOCON Board2-23
the Address(23:0) and Data(15:0) busses. The Flash memory contains host firmware, DSP firmware, 
and codeplug data with the exception of the tuning values that reside on the transceiver board’s 
serial EEPROM. The Flash memory IC is not field repairable.
The RESET_OUT of the dual-core processor is at a GPIO voltage logic level. Components D401 and 
R401 are used to convert the voltage down to a 1.8 V logic level, and this 1.8 V reset...

November 11, 20046881094C12-A
2-24Theory of Operation: VOCON Board
The audio and power supply IC (GCAP II IC) has many functions. It supplies most of the voltages 
used on the VOCON board, while external linear regulators supply 5 Vdc and 1.55 Vdc. It also has 
microphone audio amplifiers, switching between internal and accessory microphones, multiplexing 
capability for receive and transmit audio, filtering, voltage regulators, a real-time clock (RTC), and the 
audio CODEC. The audio CODEC performs...

6881094C12-ANovember 11, 2004
Theory of Operation: VOCON Board2-25
Audio Circuitry
A 13-bit CODEC, internal to the GCAP II IC and programmable by the dual-core processor through 
the SPI bus, converts microphone audio into a digital bit stream for processing by the DSP. The 
CODEC also converts receive audio data that was processed by the DSP into an analog audio signal 
for amplification to a speaker. The CODEC interfaces to the DSP through the 4-wire SAP bus. The 
CODEC clock, which is 256 kHz and is...

November 11, 20046881094C12-A
2-26Theory of Operation: VOCON Board
2.5.2.2.6  EEPOT U509
The EEPOT is a digitally programmable potentiometer with 256 taps and a total resistance of 50 
Kohms. This 10-pin package contains two independent potentiometers, one for each microphone 
line. The EEPOT resistance values are programmed by the dual-core processor GPIOs 
EEPOT_INC* (U509 pin 9) and EEPOT_U_D* (U509 pin 2). The EEPOT_INC* signal increments the 
resistance value up or down, which depends on the...

6881094C12-ANovember 11, 2004
Theory of Operation: VOCON Board2-27
Side Connector Interface, Logic Level Translation, and Boot Data Path Control
The digital-support IC facilitates the interface to the radios side connector. Some of the side 
connector lines are at 5 V logic levels, so the digital-support IC converts those lines to GPIO voltage 
logic levels to interface to the dual-core processor. These lines include the SB9600 bus busy line 
LH_BUSY (R242), and the RS 232 CTS (R245).The SB9600 data line...

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2-28Theory of Operation: VOCON Board
Watchdog Timer
The digital-support IC monitors the position of the radio’s On/Off switch on the BP_SEN_X pin, and 
that signal is located on Q508 pin 3. If the voltage on pin 3 is ground, then the radio is turned on. If 
the voltage on pin 3 is 3 volts, then the radio is off. When the radio is turned off, a counter inside the 
digital-support IC begins incrementing. That counter can be refreshed by the dual-core processor 
through the SPI...