DRV8214

A buddy of mine dropped me a link to TI’s new brushed DC motor driver with sensorless speed control, the DRV8214. I spent a few minutes trying to hunt down the mechanism they use to derive speed from back EMF because it’s such an intriguing idea, and the datasheet proper is slightly cagey abut it… but it looks like they’ve fundamentally figured out how to build in the sensing and control loop from the filtered ripple counter mechanism (PDF) they previously published a guide for doing with discrete H-bridge/current sense/op amp/comparitor ICs and an MSP430 microcontroller directly into a $3-in-single-quantity I2C addressable chip.
It even has stall detection that looks good enough to potentially use for sensor-less homing.
Interfacing to a host micro is fairly pin-and-peripheral intensive, but this seems like good magic.