This week’s EYE ON NPI (video) will take you for a SPIN around the block – it’s STMicroelectronics’ STSPIN32G0 Three-Phase BLDC Controller series of chips, featuring 250 or 600 V three-phase BLDC FET controllers with integrated embedded STM32 MCU!
These chips are an ‘all in one’ solution to advanced motor control when you want to have sensors and tight integration, or a super tiny footprint.
As budding robotics hobbyists, we’ve designed and stocked many products – like this Motor Shield – to support a variety of small DC motors.
Some well known varieties are: Hobby Servos, DC brushed motors, and steppers. Hobby servos are actually just DC brushed motors with a feedback circuit, so we’ll ignore those.
DC brushed motors are simple: apply a positive DC voltage to the two wires, and the rotor spins one way. Apply a negative voltage, they spin the other way. As you can expect from the name, inside are brushes, that connect from the rotating center to the two permanent magnets on the outer diameter.
This makes them inexpensive, and very easy to use: simply PWM the voltage to change the speed, invert the voltage to change direction. Nothing more complex than an H-bridge is required. But the brushes do eventually wear out, or oxidize, or splinter. Which means the motors will eventually ‘die’ and need replacement. Fine for toys and simple products that have low usage, but not appropriate for white goods or automotive or anything where life-time and reliability are essential!
Stepper motors are a tad more complex: in order to have precise movement, they use a bank of 4 electromagnetic coils to ‘step’ the axle around a little bit at a time. No brushes to replace! But they don’t rotate fast: the point is they have small accurate steps, and they’re kinda expensive.
What if we could combine DC brushed motors and steppers to create… Brushless DC Motors? Wow, so smart! That’s exactly what a BLDC is, a DC motor that has no brushes, but does have multiple windings that have to be synchronized right to rotate. They’re a little more expensive than brushed motors, but not significantly. The biggest cost increase is in the driver complexity because you need to drive and sequence three branches, whereas the commutator/brushes on a brushed motor handles that for you.
Normally folks will use their favorite microcontroller, then wire it up to a BLDC driver, like the L6235Q which can push 2.5A per-bridge at up to 52V. But, wouldn’t it be nifty if you didn’t have to do any wiring, so that even for small designs, you can have a fully integrated motor controller with your main microcontroller. Or, you could use the microcontroller as an I2C or SPI peripheral that integrates the temperature/current/voltage/torque monitoring that you would normally have to manage as a interrupt-run thread on a main core.
That’s what we’ve got here with the STSPIN32G0 Three-Phase BLDC Controller series of chips. It’s a ARM Cortex M0 STM32G031C8 running at 64MHz and 64K flash / 8K SRAM, with standard peripherals, debug, and even some 5V-friendly GPIO.
Inside, the STM is bonded to the control circuitry so that 3 sides are used for microcontroller interfacing, and the fourth side is high-voltage friendly with separated pads.
Program it just like any other STM32G031C8, and just define the motor control pins to the bonded wires. And then you’ll need to connect the 6 power IGBT/FETs to create the 3 driving half-bridges such as STGD6M65DF2.
Are you ready to have a super-integrated BLDC driver board that comes with a top-notch Cortex-M0 and all the power-driving experience ST has to offer? You’re in luck because the STSPIN32G0 Three-Phase BLDC Controller is in stock right now at DigiKey for immediate shipment.
Check out the all-in-one EVSPIN32G06Q1S1 eval board if you want to immediately start testing out the STSPIN32G0. Then place your order today so you can start putting your own spin on motor driving by tomorrow afternoon.
See the video below:
