Polling, Interrupts and muCOS-II: A Comparative Timing Response Simulation Model for Wireless Processor-to-Processor Communication

The paper aims to analyze the timing performance characteristics of systems employing polling, interrupts and a Real Time Operating System (RTOS). The RTOS used, specifically, is uCOS-II. The analysis incorporates a model of an Industrial system made up of microcontrollers which communicate using Zigbee protocol and data is send and received over serial ports of the microcontrollers. One microcontroller functions as the sensor node and the other is the master which receives values from sensor node and sends out appropriate control commands in response to received sensor data. The performance of the master node is taken into account since all monitoring and control is being dedicated to this master node. A physical condition of the industrial environment is sent, and in the model we shall send real time temperature values from sensor node to master node such that when set points are exceeded then master controller sends a command to switch ON cooling system to sensor node. The time taken from when sensor node sends an out of range temperature value up to the time it will receive control command from master node is used to determine the time response of the system under the three scenarios of polling, interrupts and an RTOS. Thus the analysis aims to see how polling the serial port, serial interrupts and an RTOS affect the response, predictability and deterministic behavior of the system.