Tips for doing effective hardware/firmware codesign

By Gary Stringham, Gary Stringham &Associates, LLC
Embedded.com (August 31, 2013)

In an embedded system, hardware and firmware each have their respective jobs to do but must work together as a system. Coordination must occur between hardware and firmware, especially to keep both working optimally.

However, if the system is not balanced, performance could be impacted if firmware is waiting for hardware to finish something or if hardware is waiting for firmware to say what to do next.

Firmware has to wait for hardware to complete a task. In the meantime, firmware often busies itself with other tasks. But if hardware does not generate any kind of task completion signal, firmware is often left guessing and accommodating a worse-case scenario. On the other hand, if firmware is too busy to respond to interrupts from hardware, hardware is left idling and possibly could miss external events it needs to handle.

Timing is not the only aspect, but efficiency across the hardware/firmware interface is a factor, too. Inefficient designs are prone to defects that need to be detected and resolved. In this chapter I will discuss several design aspects that will help hardware and firmware work more efficiently to increase performance and reduce unnecessary waiting.

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