Designing and Building Embedded Computer Systems: A Comprehensive Guide

Computer engineering, particularly when it comes to embedded systems, is a multifaceted process that requires deep understanding of hardware and software components. The design and construction of these systems are as intricate as they are critical. This guide will delve into the key considerations and steps involved in crafting an effective embedded computer system.

Introduction to Embedded Systems

Embedded systems are specialized computer systems designed to perform specific functions. They are integrated into larger systems, such as automobiles, home appliances, medical devices, and industrial machinery. By focusing on specific functionalities, embedded systems offer tailored solutions that are often more efficient and cost-effective than general-purpose systems.

Key Considerations During Design

The journey from initial idea to a fully functional embedded system involves several critical steps. Here are the primary questions and considerations that must be addressed:

Budget and Production Goals

The budget allocated for research and development (RD) and the final product's production costs play a crucial role in the design process. Depending on the planned production volume, trade-offs may need to be made. For instance, if a large number of units are planned, more investment in advanced components might be justified. Conversely, for smaller production runs, cost-effective solutions might be preferred.

Question: What is the budget for RD and the cost per delivered board?

Timeline and Scheduling

The timeline for delivering the first system is another important factor. The available time can significantly influence the scope of the project and the technologies that can be utilized. A well-planned schedule ensures that the system is delivered on time without compromising quality.

Question: When do you need to ship your first system?

Application Requirements

Understanding the applications that the system will run is essential for optimizing its performance. Each application has specific resource requirements for RAM, flash storage, processing power (MIPS), and input/output (I/O) bandwidth. These requirements help in allocating the necessary resources to ensure efficient system operation.

Question: What applications does the completed system need to run?

Interface Support

The system must support a wide range of input and output interfaces to ensure compatibility with various external devices. These interfaces can include Ethernet, GPIB, Wi-Fi, Bluetooth, serial communication, CAN (Controller Area Network), ARINC, PLC (Programmable Logic Controller) communication, fiber optics, pulse-width modulation (PWM), analog signals, and more.

Question: What interfaces need to be supported?

Software and Operating Systems

The system's operating environment is critical. Some systems may need to run specific operating systems (OS) or adhere to certain publish/subscribe models. Custom drivers for custom peripheral devices may also be required.

Question: Does the end product need to support a specific OS or set of publish/subscribe models? Will custom drivers be needed?

Power Consumption and Efficiency

Power consumption is a key consideration, especially for portable devices or systems with strict power constraints. The system must be designed to meet power draw requirements in both standby and full workload modes. This often involves optimizing hardware and software to minimize energy usage.

Question: How much power is the system allowed to draw in both standby and full workload modes?

Environmental Conditions

Operating temperature ranges can significantly impact the design and functionality of the system. Devices intended for extreme environments, such as turbine engines or satellite components, need specialized design considerations. Domestic applications like cell phones have different temperature constraints.

Question: What are the expected temperature ranges?

Product Development and Implementation

Armed with the answers to these key questions, the next step is to draft a block diagram that outlines the architecture of the system. This diagram should include:

Processors (CPU, GPU, DSP, etc.) Interfaces (Ethernet, GPIB, Wi-Fi, etc.) Memory (RAM, flash storage) Application-specific integrated circuits (ASICs) FPGA (Field-Programmable Gate Array)

For each component in the block diagram, candidate components are selected for the initial revision (rev 0.1). This process involves evaluating and selecting components based on their performance, cost, and compatibility with the overall design requirements.

Steps for Component Selection:

Identify the required specifications for each component. Select candidate components that meet the specified requirements. Perform simulations and prototyping to refine the design. Optimize the system for power, performance, and cost efficiency.

Conclusion

Designing and building an embedded computer system is a meticulous process that demands a deep understanding of multiple factors. By addressing the key questions outlined in this guide, engineers can create systems that are not only functional but also efficient and cost-effective. The use of well-defined requirements and meticulous design steps ensures that the final product meets the necessary standards and performs as intended.

For a more detailed exploration of the design process, The Soul of a New Machine by Tracy Kidder is an excellent resource that delves into the world of embedded system design with historical context and rich storytelling.