Expansion Head; Overview; General; Circuit Description - Motorola MTM700 Detailed Service Manual

4.3 - 6

Expansion Head

Overview

The Expansion Head GMCE4053A is a hardware interface to the MTM700 TETRA mobile radio. It
gives access to the radio via three front side connectors. The following interfaces and protocols are
provided:
- 8-wire RS232 Interface (9-pin D-type connector)
- 4-wire RS232 Interface (25-pin D-type connector)
- SB9600 Interface (25-pin D-type connector)
- SBEP Interface (10-pin Telco connector)
- 14 pin JTAG port

General

The 25-pin D-type, the 9-pin D-type connector and the 10-pin Telco connector are mounted on the
Connector Board that is screwed into the Expansion Head housing. The Milan Expansion Board is
installed at expansion board position. The interconnection between the Connector Board and the
Milan Expansion Board is accomplished by a 40-pin flex connector.
A 12-pin flex and a 40-pin flex achieve the connection between the Expansion Board to the main
radio chassis. A remote mount control head can be connected in a remote mount configuration via
the 10-pin Telco connector. External DCE(s) can be connected via the 25 pin and /or 9 pin D type
connectors.

Circuit Description

The Expansion Head Interface consists of several circuits to provide interfaces for the MTM700
TETRA mobile radio and the „outside world". The Expansion board has an onboard 3-Volt Regulator
U1091 that is driven by 5-Volt supply from the main radio via the 12-pin flex.
There are several interfaces on the board but not all of them are available at the same time.
The 8 wire RS232 interface consists of the MAX3238 true RS-232 transceiver (U1065) that provides
the EIA/TIA-232 and V.28/V.24 communications interface. This interface can be fully accessed
through the 9-pin D-connector.
The circuit comprising ICs U1015, U1016 and U1010 interfaces the MTM700 SPIB bus to an asyn-
chronous serial-data communication port RS232 that is the 4-wire RS232 interface (pins 2, 3, 4, 5).
U1015 is a MAX3100 universal asynchronous receiver transmitter (UART) with a baud rate genera-
tor driven by a 3.6864 MHz crystal U1010. U1016 is a MAX3232 RS232 transceiver, translating the
3V logic levels to the RS232 levels.
The next interface is a SB9600 interface on the 25-pin connector (pins 8, 13, 15, 17)
(SB9600_INTERFACE). The UART chip U1015 also generates the transmit/receive signals of this
interface.
The SBEP interface is provided on the 10-pin Telco remote connector. All signals necessary to con-
nect a remote mount controlhead are routed through this connector. Those signals are fed from the
MTM700 Mobile Radio / Detailed Service Manual THEORY OF OPERATION (CONTROL HEADS)