Today's embedded designs based on microcontrollers often include a combination of analog and digital signal content. Design engineers have traditionally used both oscilloscopes and logic analyzers to test and debug these types of embedded designs. But a new class of measurement tool known as a mixed signal oscilloscope (MSO) may be a superior tool for your microcontroller-based debugging applications. Although MSOs have been on the market for nearly ten years, most engineers have never used one and there are many misconceptions about their benefits and use-model. With more oscilloscope vendors bringing hybrid time-domain instruments on the market today that merge analog and digital measurement capabilities, it is important that you understand some of the differentiators between these instruments and be aware of what they can and cannot do.

This paper begins with an overview of the primary applications where MSOs should be used. Using an example of a mixed-signal embedded design based on a 16-bit wide instruction-set microcontroller from Microchip Corporation (PIC18), this paper not only discusses the number of channels of acquisition required to effectively monitor various analog and digital I/O signals, but also covers the various types of mixed-signal triggering you should look for in an MSO to test and debug a design such as this. One of the functions of this particular mixed-signal embedded design based on the PIC18 is to generate various length analog chirp signals under I2C serial bus control commands. Using serial triggering, this paper will show how an MSO can easily synchronize acquisitions on particular analog chirps so that the scope's analog acquisition system can be used to measure the quality of each chirp.

Johnnie Hancock is a Signal Integrity Applications Engineer within Agilent Technologies Electronic Products Group. He began his career with Hewlett-Packard in 1979 as an embedded hardware designer, and holds a patent for digital oscilloscope amplifier calibration. Johnnie is currently responsible for Agilent's digitizing oscilloscope measurement applications and has authored many papers and regularly speaks at technical conferences. Johnnie graduated from the University of South Florida with a degree in electrical engineering. In his spare time, he enjoys cross-country running and restoring his 110-year-old Victorian home.

This presentation is intended primarily for hardware designers of embedded 8- & 16-bit microcontroller-based applications that involve a combination of both analog and digital signals. These types of designs are very prevalent across a broad range of industries worldwide including consumer, automotive, industrial, and aerospace/defense.