General Purpose Input/Output; Normal Microprocessor Operation - Motorola GM-950 Manual

Open Controller
2.11

General Purpose Input/Output

The Controller provides one general purpose line (GP I/O) available on the accessory connector
J0400-12 to interface to external options. The software and the hardware configuration of the radio
model defines the function of the port. The port uses an output transistor (Q0432) controlled by µP
via ASFIC port GCB3 (pin B3) and an input transistor (Q0431) read by µP port PA7 (pin 4). To use
the GP as input the µP must turn off the output transistor.
An external alarm output, available on J0400 pin 4 is generated by the µP via ASFIC port GCB1 (pin
A3) and transistor Q0411. Input EXTERNAL PTT on J0400 pin 3 is read by the µP via line REAR
PTT and µP pin 8.
From version 0102726B09_Cntl on: Pin 13 of the accessory connector J0400 provides a voltage at
battery level while the radio is switched on. The output is capable to drive a dc current up to 300 mA
and has a short circuit protection. When the radio is switched on, the voltage 9V3 turns on transistor
Q0482. Transistor Q0482 switches on Q0481 and enables a current flow from emitter to collector of
Q0481. This path has a very low impedance and effectively provides the same voltage level at SW
FLT A+ as at FLT A+. If the radio is switched off the voltage 9V3 is at ground level which switches off
Q0482 and in turn cuts off the current from emitter to collector of Q0481. If the accessory connector
output J0400-13 is connected to ground while the radio is on, the diode D0481 pulls the base of
Q0482 down to about 0.6V. With a voltage drop of about 0.6V across D0482 the base to emitter
voltage of Q0482 is about 0V. This cuts off the collector current of Q0482 and switches off Q0481
until the short is removed.
2.12

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 three external memory devices;
U0102 (FLASH EEPROM), U0103 (SRAM), U0104 or U0107 (optional EEPROM). Also, within the
µP there are 768 bytes of internal RAM and 640 bytes of internal EEPROM, as well as logic to select
external memory devices.
The (optional) external EEPROM (U0104 or U0107) as well as the µP's own internal EEPROM
space contain the information in the radio which is customer specific, referred to as the codeplug.
This information consists of items such as: 1) what band the radio operates in, 2) what frequencies
are assigned to what channel, and 3) tuning information. In general tuning information and other
more frequently accessed items are stored in the internal EEPROM (space within the 68HC11K1),
while the remaining data is stored in the external EEPROM. (See the particular device subsection
for more details.)
The external SRAM (U0103) as well as the µP's own internal RAM space are used for temporary
calculations required by the software during execution. All of the data stored in both of these
locations is lost when the radio powers off (See the particular device subsection for more details).
The FLASH EEPROM contains the actual Radio Operating Software. This software is common to all
open architecture radios within a given model type. For example Securenet radios may have a
different version of software in the FLASH EEPROM than a non-secure radio (See the particular
device subsection for more details).
5C.3-6 Theory of Operation