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MIT Handy Board
Grifo GPC-114
RS485 network card
GPC-114 Universal Controller

GCP-114 controller card is manufactured in Italy by Grifo.

This is an excellent card for small projects requiring communication over the RS232/422/485 interface, process control based on RTC with 8-channel analog input, digital input/output or data collection via Abaco I/O Bus.

Flexible memory configuration allows to configure this card for use with the battery backed-up SRAM, EPROM or EEPROM.

Java application example described on this page shows how to use Java VM for 68HC11 with this controller board.

Hardware configuration

GPC-114 has been configured as follows:
RS232 port for communication with host PC
24KB battery backed-up SRAM
22KB SRAM (no backup)
16KB EPROM (J6 & J7 closed)
Added 'boot' switch connected to MODA/MODB pins of 68HC11 to allow loading programs from the host PC

Java application

A simple menu driven application has been written that can perform following tasks:
Send and receive data from the host PC via RS232
Display menu options
Set new date
Set new time
Continuous display of current date & time
RTC Start/Stop function
Change 12/24 time format

Application is controlled from the host PC running the serial communication software like HyperTerminal under Windows or Minicom under Linux.

When Java program is started it transmits welcome message and shows list of available commands. It then waits for a command from the host PC. When a 'Show Date/Time' command is received Java program continuously transmit current time read from RTC chip.

Download Java application

Java application source code is available in zip format. After downloading unzip the GPC114.ZIP into folder where you have previously installed Java VM for 68HC11. Use unzip utility that supports long file names with create sub-folders option enabled. The binary size of this Java application is about 9.7KB.

 GPC114.ZIP (50KB)

What is required:

Java VM for 68HC11 - Beta 2
GNU ASxxxx assembler/linker, executables for Windows platform can be downloaded from here or visit the ASxxxx home page to download tools for other platforms.
JDK1.2 (or JDK1.1.x) to compile Java application and to run ClassLinker
Sun's CommAPI 2.0 if you want to use AppLoad - the Java application for loading binaries via 68HC11 bootstrap mode.

GPC-114 memory map





68HC11 interrupt vectors

Java VM + interrupt vectors redirection code

Real Time Clock registers 16 Bytes


On board resources - Abaco Bus, /ECS1     


Garbage collected application heap 22KB
(no backup)



Java application
CPU control registers

Native code, Java VM data space
Real interrupt vectors

(battery backed-up)


68HC11 internal RAM 256 Bytes



One special feature worth noting is that the interrupt vectors are located at $100 and are set when startup/native code is loaded into memory. When an interrupt occurs, special interrupt handling code in the EPROM fetches real vectors from corresponding offsets at $100. This feature allows to have Java VM permanently loaded in the EPROM. There is no need to re-program EPROM every time a new Java application is loaded.

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