Motorola Gm328 Gm338 Gm398 Detailed 6804112j18 E Manual

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Table of Contents
Section 1 Theory of Operation
1.0 Controller Circuits ................................................................................................ 1-1
1.1 Overview......................................................................................................... 1-1
1.2 General ........................................................................................................... 1-1
1.3 Radio Power Distribution...

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Section 3 Controller Schematics / Parts Lists
1.0 Allocation of Schematics and Circuit Boards ....................................................... 3-1
1.1 Controller Circuits ........................................................................................... 3-1
1.2 Voice Storage Facility..................................................................................... 3-1
2.0 Controller T5 / Schematic Diagrams .................................................................... 3-3...

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Section 1
THEORY OF OPERATION
1.0 Controller Circuits
1.1 Overview
This section provides a detailed theory of operation for the radio and its components. The main radio 
is a single board design, consisting of the transmitter, receiver, and controller circuits. The main 
board is designed to accept one additional option board. This may provide functions such as secure 
voice/data, voice storage or signalling decoder.
A controlhead is either mounted directly or connected by an extension cable. The...

1-2Controller Circuits
Figure 1-1 Controller Block Diagram
1.3 Radio Power Distribution
The DC power distribution throughout the radio board is shown in Figure 1-2. Voltage regulation for 
the controller is provided by 4 separate devices; U0651 (MC78M05) +5V, U0641 (LM2941) +9.3V, 
U0611 (LM2941) SWB+ limited to 16.5V and VSTBY 5V (a combination of R0621 and VR0621). An 
additional 5V regulator is located on the RF section.
The DC voltage applied to connector J0601 supplies power directly to the...

Controller Circuits1-3
Transistor Q0681 and resistors R0681 / R0682 divide the regulated 9.3V down to about 6 volts. This 
voltage supplies the 5V regulator, located on the RF section.  By reducing the supply voltage of the 
regulator, the power dissipation is divided between the RF section and the controller section.
The voltage VSTBY, which is derived  directly from the supply voltage by components R0621 and 
VR0621, is used to buffer the internal RAM. C0622 allows the battery voltage to be...

1-4Controller Circuits
1.4 Electronic ON/OFF
The radio has circuitry which allows radio software and/or external triggers to turn the radio on or off 
without direct user action. For example, automatic turn on when ignition is sensed and off when 
ignition is off.
Q0661 is used to provide INT SW B+ to the various radio circuits and to enable the voltage 
regulators via transistor Q0641. Q0661 contains an pnp and an npn transistor and acts as an 
electronic on/off switch. The switch is on when the...

Controller Circuits1-5
1.6 Mechanical ON/OFF
This refers to the typical On/Off/Volume knob, located on the controlhead, and which turns the radio 
on and off.
If the radio is turned off and the On/Off/Volume knob is pressed, line ON OFF CONTROL (J0401 pin 
11) goes high and switches the radio’s voltage regulators on as long as the button is pressed. The 
microprocessor is alerted through line ON OFF SENSE (U0101 pin 6) which is pulled to low by 
Q0110 while the On/Off /Volume knob is pressed. In...

1-6Controller Circuits
The ASFIC CMP synthesizer loop uses C0245, C0246 and R0241 to set the switching time and jitter 
of the clock output. If the synthesizer cannot generate the required clock frequency it will switch 
back to its default 3.6864MHz output.
Because the ASFIC CMP synthesizer and the µP system will not operate without the 16.8 MHz 
reference clock it (and the voltage regulators) should be checked first in debugging the system.
The microprocessor uses XTAL Y0131 and associated components...

Controller Circuits1-7
1.10 SBEP Serial Interface
The SBEP serial interface allows the radio to communicate with the Customer Programming 
Software (CPS), or the Universal Tuner via the Radio Interface Box (RIB). This interface connects to 
the microphone connector via controlhead connector (J0401-8) and to the accessory connector 
J0501-17 and comprises BUS+. The line is bidirectional, meaning that either the radio or the RIB 
can drive the line. The microprocessor sends serial data via pin 98 and D0101...

1-8Controller Circuits
1.12 Normal Microprocessor Operation
For this radio, the µP is configured to operate in one of two modes, expanded and bootstrap. In 
expanded mode the µP uses external memory devices to operate, whereas in bootstrap operation 
the µP uses only its internal memory. In normal operation of the radio the µP is operating in 
expanded mode as described below.
In expanded mode on this radio, the µP (U0101) has access to 3 external memory devices; U0121 
(FLASH EEPROM), U0122 (SRAM),...