Cross Breeding DSPs and Microcontrollers

As processing devices continue to get faster, smaller, and lower power, the ability to integrate more functionality into a single device is more easily realized. Advances in core architecture and process technologies are allowing system-on-chip (SoC) methodologies to proliferate. Stand-alone DSPs (digital signal processors) are an example of devices becoming a thing of the past in many applications. As Robert Cravotta’s article “The evolving landscape of Digital Signal Processing” highlights, there have been many new ways of integrating pieces of a DSP into MPUs (microprocessors), MCUs (microcontrollers), and software packages to include the required functionality, yet eliminating the extra chip onboard.

Many of today’s applications require some level of signal processing, but don’t need a standalone DSP. These applications may require the ability to multiply and accumulate (MAC) – at the heart of a DSP. They may even require some advanced filtering techniques, FIR or IIR for instance. This type of functionality is often found or easily implemented in firmware on most of today’s microcontrollers. From cell phones to home appliances and industrial motor controls, the MCU cores that run these applications are capable of integrating signal processing without requiring a separate DSP. By integrating the signal processing functionality, rather than adding an additional DSP onboard, a designer can ultimately save board space, lower power consumption, reduce the overall BOM (bill of materials), and ultimately lower cost.

To combat this trend, we have even seen some of the DSP giants release their own form of ‘hybrid’ DSPs, which combine DSP signal processing with microcontroller peripherals and functionality. More fire to the argument that signal processing is becoming a feature of today’s processors, rather than a stand-alone chip.

Atmel’s recently launched maXTouch touch controller contains built-in signal processing that eliminates the need for a stand-alone DSP. Internally this chip does filtering and signal processing to remove noise and provide jitter free XY coordinates, gesture recognition, and processing for rejection of unintended touches from the user—in a single chip. In earlier years, this type of device may have needed a stand-alone DSP for the same functionality. Fortunately, today’s processor technologies allow us to include the signal processing and drop the DSP, minimizing board space, lowering power consumption and ultimately lowering cost.

John Carey, Technical Marketing Manager, Atmel