Analog microcontrollers certainly aren't new. But they've advanced dramatically by getting smaller, more powerful, and less expensive. And their applications are far-ranging, from process and motor control to interfacing with the latest micromachines, such as 3D accelerometers.
Despite the presence of analog microcontrollers, analog system design is still tough. Current analog-microcontroller options may not be as extensive as the number of op amps or comparators on the market, but they come close in magnitude. Even soft devices like Cypress Semiconductor's PSoC come in a range of configurations. Of course, the PSoC has advantages. The diagram shows only a section of its dynamically configurable analog array. With it, designers can create a wide range of analog services on-chip. This feature can even be dynamically reconfigured.
Still, the PSoC approach doesn't meet all requirements. Texas Instruments' MSP 430 has an analog-to-digital converter (ADC) that can be cycled through a set of multiplexed inputs and deposit the results directly into memory, minimizing application overhead. Likewise, Silicon Laboratories' C8051F064 can funnel the data from its two 16-bit ADCs to an output port at 1 Msample/s with no program intervention (see ED Online 8397 at www.elecdesign.com).
But is faster always better? Sometimes, accuracy is more important. Sometimes, it's sensitivity. Even analog input and output conditioning may be a requirement. Does the host processor require 8, 16, or 32 bits? Finding the right microcontroller for a job can be difficult, but it's well worth searching. Just make sure you know all the requirements up front.
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