Sbep Serial Interface; General Purpose Input/Output - Motorola GM328 Service Manual

Controller Circuits
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 and it reads serial
data via pin 97. Whenever the microprocessor detects activity on the BUS+ line, it starts
communication.
In addition, the SBEP serial interface is used to communicate with a connected controlhead. When a
controlhead key is pressed or the volume knob is rotated, the line ON OFF CONTROL goes high.
This turns on transistor Q0110 which pulls line ON OFF SENSE and µP pin 6 to ground level. In
addition, an interrupt is generated at µP pin 96. This indicates that the controlhead wants to start
SBEP communication. The microprocessor then requests the data from the controlhead. The
controlhead starts sending and after all data has been send, the ON OFF CONTROL line goes low.
The controlhead ignores any data on BUS+ during SBEP communication with the CPS or Universal
Tuner.
1.11

General Purpose Input/Output

The controller provides eight general purpose lines (DIG1 through DIG8) available on the accessory
connector J0501 to interface to external options. Lines DIG IN 1,3,5,6, are inputs, DIG OUT 2 is an
output and DIG IN OUT 4,7,8 are bidirectional. The software and the hardware configuration of the
radio model define the function of each port.
DIG IN 1 can be used as external PTT input, DATA PTT input or others, set by the CPS.
The µP reads this port via pin 77 and Q0171.
DIG OUT 2 can be used as normal output or external alarm output, set by the CPS. Transistor
Q0173 is controlled by the µP via ASFIC CMP pin 14.
DIG IN 3 is read by µP pin 61 via resistor R0176
DIG IN 5 can be used as normal input or emergency input, set by the CPS. The µP reads this port
via R0179 and µP pin 60. Diode D0179 limits the voltage to protect the µP input.
DIG IN 6 can be used as normal input, set by the CPS. The µP reads this port via pin 74 and Q0181.
DIG IN OUT 4,7,8 are bi-directional and use the same circuit configuration. Each port uses an
output transistor Q0177, Q0183, Q0185 controlled by µP pins 46, 47, 53. The ports are read by µP
pins 75, 54, 76. To use one of the ports as input the µP must turn off the corresponding output
transistor.
In addition the signals from DIG IN 1, DIG IN OUT 4 are fed to the option board connector J0551
and the expansion board connector J0451.
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