Processor And Interconnect Pcbs Circuit Description - Raymarine RAY 240 Manual

RAY 240 Processor and Interconnect PCBs Circuit
Description
Introduction
The processor board is the central control unit of the Ray240 VHF system. It controls the system in
response to commands received from the handsets and, conversely, reports the system status to the
handsets for display.
In addition, the processor board provides power supply filtering; the auxiliary external
communications functions, Seatalk and NMEA0183; the loudhailer function and optional plug-in
telephone line interface.
An edge connector on the processor board accepts the interconnect board through which connections
to the handsets, power source and external interfaces are made. Three further board-to-board
connectors mate with the radio board, which contains the rf functions.
The interconnect board may be considered an extension to the processor board on which the
transceiver's external connectors are mounted. The interconnect board is central to the EMC design
strategy, having the EMC or "clean" ground plane to which signals entering and leaving the
transceiver are filtered and shields terminated.
The processor and interconnect board hardware are shown in the block diagram.
Power Supply
The 12V battery supply enters the transceiver at the power connector on the interconnect board. The
battery supply is protected with a 10A automotive style fuse in the positive line, located on the
interconnect board and accessible without removing the transceiver cover. In the event of reverse
supply connection a power diode conducts and blows the 10A fuse.
After filtering on the processor board the 12V supply is distributed to the radio board and handsets.
The handset supplies are individually protected with 1.8A reset-able fuses, located on the
interconnect board.
The voltage monitor sends a dc level proportional to the supply voltage to one of the
microcontroller's analogue to digital converters. This allows software to detect an over-voltage
condition, for example connection to a 24V supply. When an over-voltage is detected the
microcontroller disables the transmitter and receiver modules on the radio board, to prevent damage,
and alerts the user with a message on the handset display.
On the processor board the 12V supply is regulated to 5V to supply the electronics. Two regulators
are used: one for the digital circuits and one for the analogue. The hailer power amplifier,
NMEA0183 transmitter and handset communications interface are powered from the unregulated
12V supply. The processor board draws 75mA typ. from the 12V supply.
Microcontroller
The processor board is built around a 16-bit microcontroller, Motorola MC9S12DG128CPV. It has
128kbyte flash memory that is programmed via the BDM (background debug mode) port, 8k RAM,
2k EEPROM and a variety of on-chip peripherals that are used to control and monitor the system.
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