A systematic approach to software peripherals for embedded systems

The continued growth of microprocessors' performance and the need for better CPU utilization, has led to the introduction of the software peripherals' approach: By this term we refer to software modules that can successfully emulate peripherals that, until now, were traditionally implemented in hardware. Software implementations offer great flexibility in product design and in functional upgrades, while they have high contribution in the cost/performance ratio optimization. We focus on embedded applications, where the cost and the short time to market are the leading issues. In this paper, we study the hardware and software requirements for developing a generic microprocessor with support for software peripherals. Additionally, we present three software peripherals, a Universal Asynchronous Receiver Transmitter, a keypad controller and a dot matrix LCD controller, and we analyze their impact in CPU occupation. Finally, we explore the impact of using a software UART on system power dissipation.