Heterogeneous embedded system with 'microcontroller-CPLD' based shared memory interface for sensor applications

Abstract

The paper describes design of a heterogeneous embedded system with CPLD and microcontroller as coprocessors sharing a memory module. The system comprises of a microcontroller with built in ADC catering to the requirements of sensor interfacing. Device drivers have been developed to sample the analog output of the sensors and are subsequently stored in the shared RAM for further processing by the CPLD module. The CPLD has been configured as a customized digital signal processor with the required utilities for data processing. The processed data by the CPLD is further converted back to analog domain in order to actuate the final control elements. The developed interface is a standalone embedded system, which is programmed through the centronix and RS-232 interface using PC. The board has been tested with IC temperature sensors and also found to be useful for sensor array applications. The system exhibits three types of processing viz. analog (through instrumentation amplifier), real time digital (through microcontroller) and customized reconfigurable digital (with the CPLD).