This week on EYE on NPI (video above), folks who have wanted us to cover more motor controllers will see we’re taking a STEP in the right DIRECTION with the TMC2226-SA Ultra-Silent Stepper Motor Driver with Step/Direction.
There’s a lot of makers of stepper motor drivers these days – which means that companies are innovating a lot to stay ahead of the competition. Trinamic’s stepper drivers have some interesting features we haven’t seen in other drivers. And the price is good too! Only about $1.60 in quantity. For folks who have used Trinamics before, the new TMC2226 has a larger TSSOP package with heat dissipation thermal pad, much lower RdsOn LS 170mΩ & HS 170mΩ (compare to TMC2208’s LS 280mΩ & HS 290mΩ) so that it can handle 2.8A current peak & 2A RMS (compare to TMC2208’s 2A peak & 1.4A RMS) so this will be a very nice upgrade for CNC machines that need more drive!
Here’s what they have to say:
Programmable via UART and featuring some of Trinamic’s latest-generation technologies, the highly dynamic stepper driver is ideal for design upgrades with compatible drivers. Ensuring noiseless operation with StealthChop2™, the chip enables smooth and silent stepper motors for everyday use. At the same time, the sophisticated chopper increases efficiency and motor torque compared with normal choppers.
Once tuned, engineers can simply store the settings on the OTP memory and use it for standalone motion thanks to the internal pulse generator. This makes the TMC2226 an effective and cost-efficient solution for printers and POS devices, office and home automation, textile, security, ATMs and cash recyclers, as well as battery-operated equipment.
The big thing Trinamic promotes with their stepper technology is their “StealthChop2” silent motor operation. Those who have played with stepper motors know that once you start microstepping them to get more precision, you also can get some interesting squeaks. That’s because the frequencies used to microstep cause the motor coils vibrate to vibrate in the audible 20-20KHz range. These drivers change around the chopping frequency to keep the motor silent – They even have a cool “No Loud Stepper” icon!
The next big unique thing about this chip family is that there are three modes you can use with this driver.
The first one is ‘legacy step/dir mode’. Nearly all stepper drivers have the same compatible-ish interface. You have a few power pins, a few ground pins, two to four pins for setting the microsteps-per-step, maybe some current feedback pins, and a DIR pin for direction and STEP pin that is toggled to step the motor forward or backward. The same is available on this chip, each step can be a fullstep or a microstep, in which there are 8, 16, 32, 64 microsteps per toggle. If you have an existing CNC design that you don’t want to rework, then this mode is the easiest – you simply control the gpio with any 3 or 5V logic microcontroller
The second mode is an ‘assisted step/dir mode’ that uses internal one-time-programmable EEPROM to set up custom configurations such as turning on the internal sense resistors instead of using external ones in the OTP. The EEPROM is programmed over UART which we’ll chat about next.
The third mode is most interesting, there’s a hardware simplex UART connection for register you can use to control up to 4 motor drivers. There’s a 2-pin addressing scheme so you can use the same UART for all 4 chips. This way you can set and read all sorts of registers such as doubling up the step detection so you get a step on rising and falling edge instead of per pulse, detecting a stalled motor, or changing the over-temperature protection thresholds. You can even do things like trigger multiple steps in a row with a given velocity in a free-run mode so you don’t need to trigger the step pin at all.
With high-current capability, wide voltage range, 8/16/32/64 microstepping, and all these nice extras at the same price as the competition, this chip makes for a great driver for your mechatronic project or product! To help you get started, Trinamic has published ready-to-go KiCad dev board files. This is a rarity: usually you don’t get open source layout tool files.
Digi-Key has a whole bunch of these fresh NEW products in stock right now – Go to https://www.digikey.com/
See the video below for more manufacturer information and below that a schematic for typical use.