As embedded microcontroller-based products become more sophisticated, additional emphasis is being placed on the design and implementation of their user interfaces. Visually based interfaces are commonly implemented with LCDs, LEDs, fluorescent displays, and lights. Many of these components can be controlled directly by an application’s processor without using additional components. Voicebased user interfaces, on the other hand, are often implemented with speech synthesizers, speech processors, sound generators, and digital signal processors which operate in conjunction with an application’s main processor. In addition to a processor dedicated to the generation of speech, designs frequently require a memory device to hold the data used by the processor, a loudspeaker, and audio amplification circuitry. The added cost for components and space has limited the implementation of speech-based user interfaces to higher end products and products for the visually impaired. This application note discusses adding a voice-based user interface to an application based on the Motorola MC68HC(7)05J1A microcontroller. In particular, interfacing members of the M68HC05 MCU Family to the Information Storage Devices (ISD) 1000 and 2500 family of voice record/playback devices is highlighted. The development of an audible thermometer application concludes the discussion.