Very often, complex systems involve two or more microcontrollers to fulfill the requirements defined by a given objective. Since the nature of microcontrollers
does not allow for easy dual-port memory design (no``READY'' input; no ``HOLD/HLDA'' interface; portoriented I/O etc.), design engineers are faced with the problem of interchanging information (data and status) between those microcontrollers. This application brief describes the design of a mailbox for exchanging information
between two 80C31s, using a 5C060 PLD as a ``back-to-back'' register, and a 5C032 PLD as an arbitration vehicle to control the actions of the CPUs.
CONTENTS PAGE
INTRODUCTION? 1
5C060 MAILBOX? 1
5C032 MAILBOX CONTROLLER? 2
Block Diagram? 3
5C060 ``Back to Back Register''? 4
5C032 ``Mailbox Controller''? 5
5C060 Register ADF? 6
5C032 Arbiter ADF? 7