The microcontroller guys have been kind enough to integrate some pretty nice analog circuitry on their chips, cheap!
Digital gets the most hype in the world of extreme integration, what with 1,000-pin FPGAs and 100-peripheral microcontrollers, but at least our microcontroller-designing cousins haven't forgotten about us analog guys. They've been quietly integrating impressive analog capabilities, too.
I'm sure most of you know that microcontrollers (MCUs) have long been available with analog periphery like ADCs and DACs. What I hadn't noticed till very recently is the level of performance they've attained. What caught my interest was a fantastically priced devboard from STM, which sports four 5MSa/s 12-bit ADCs and two 1MSa/s 12-bit DACs as part of its powerful Cortex-M4 chip.
OK, I know those performance levels are in the slow lane for some of you, but the overall integration is impressive, as is the price:performance ratio. In reasonable quantity, this ARM MCU goes for $5. Try assembling a gaggle of converters with similar performance for under $20.
Actually, the most striking thing about STM's $11 board is the inclusion of MEMS sensors, namely, an accelerometer, compass/magnetometer, and gyroscope -- all 3-axis! That, and the price. By the way, those MEMS devices don't eat up precious converter inputs. They may have (mechanical) analog hearts, but they interface digitally. Way to integrate, guys.
I'm not sure what I'll do with mine yet, but it's on its way. I'll think of something. Got any ideas?
For the digitally minded amongst you, ARM's Cortex-M4 architecture is its highest performing microcontroller chip. To get more processing power, you must move to the Cortex-A series -- the type of chip that's in your smartphone or tablet. The STM32F303VCT6 chip is not at the top of the M4 range, but can purr along at a respectable 90 DMIPS. There's 256KB of flash and 48KB of RAM. Add in the thousand natural peripherals that MCUs are heir to, and you've got a powerful mixed-signal solution on a chip. The CPU implements a floating-point unit and DSP extensions, too, making an even better match to signal processing applications.
Back to the analog end of things, you'll also find comparators, op-amp/PGAs, capacitive touch-switch inputs, and a temperature sensor on-chip. The ADCs can be run independently, or set to simultaneous or interleaved sampling. You can also trade off resolution with speed, reaching 9MSa/s at 6 bits, or presumably 36MSa/s when interleaved. Nice flexibility. As seems common with MCUs, the DACs get less love than the ADCs, but they're serviceable.
So why am I telling you all this? Just because I'm personally excited by the integration and price:performance levels these chips have reached -- excited enough to think that I might finally create some interesting projects with them. What are you thinking of building? C'mon, I know something has sparked in your gray matter.