# Posts by Jan

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# New product: STSPIN820 Stepper Motor Driver Carrier with 1/256 microstepping

Posted by Jan on 27 November 2018
Tags: new products

We have yet another new stepper motor driver carrier in our popular 16-pin, 0.6″ × 0.8″ form factor, this time for STMicro’s STSPIN820, which offers 1/256 step microstepping! ST actually has their own similar evaluation board, the EVALSP820-XS, but the STSPIN820 chip has a non-inverted Enable input, which is inverted compared to most other stepper motor driver ICs out there, and they expose the pin that way on their version of the board. We have thoughtfully added a transistor-based inverter so that our board is more likely to work as a drop-in replacement (or upgrade!) for the stepper driver boards you already have. In our tests, the Pololu carrier supported a substantially higher maximum current than the ST eval board (around 900 mA compared to 720 mA, probably due to our board having four layers vs. two layers for the ST eval board), and as of this writing (27 November 2018), our board is also priced lower.

You can see the full schematic for all the details (this schematic is also available as a downloadable pdf (109k pdf)):

With our release earlier in November of compact carriers for Toshiba’s TB67S249FTG and TB67S279FTG stepper motor drivers, we now offer ten different stepper motor driver modules in this compact size:

A4988(original) A4988,Black Ed. DRV8825 DRV8834 DRV8880 MP6500,Pot. CC MP6500,Digital CC TB67S279­FTG TB67S249­FTG STSPIN­820 A4988 DRV8825 DRV8834 DRV8880 MP6500 TB67S279­FTG TB67S249­FTG STSPIN­820 8 V 8.2 V 2.5 V 6.5 V 4.5 V 10 V 10 V 7 V 35 V 45 V 10.8 V 45 V 35 V 47 V 47 V 45 V 1 A 1.2 A 1.5 A 1.5 A 1 A 1.5 A 1.1 A 1.6 A 0.9 A 2 A 2.2 A 2 A 1.6 A 2.5 A 2 A 2 A 4.5 A 1.5 A 1/16 1/32 1/32 1/16 1/8 1/32 1/32 1/256 2 4 4 4 4 4 4 4 4 high current low-voltageoperation,high current AutoTune,digital currentreduction high current digital currentcontrol,high current Auto Gain Control,ADMD,high max voltage Auto Gain Control,ADMD,high max voltage,high current 128 and 256microsteps $5.95$7.49 $8.95$5.95 $6.95$5.95 $5.95$7.75 $9.95$7.75 1 On Pololu carrier board, at room temperature, and without additional cooling.2 Maximum theoretical current based on components on the board (additional cooling required).

# New G2 Simple Motor Controllers

Posted by Jan on 15 November 2018
Tags: new products

Last week, we released updated (G2) versions of our Simple Motor Controllers. We released our original Simple Motor Controllers just over eight years ago as our most economical basic motor controllers for brushed DC motors using up to a few hundred watts. The “simple” in the name came from our trying to have fun with all the requests we had from our customers, many of whom wanted “just” this one feature. Of course, everyone wants a different feature in their minimal motor controller, so the Simple Motor Controllers actually have quite a few options, but we make it easy to set up with configuration over USB.

Over the last few years, we have been updating our higher-power motor drivers (H-bridges with external MOSFETs) to use newer MOSFETs and MOSFET drivers, and we refer to them as our G2 high-power motor drivers. These drivers are available as small, single-channel boards, as well as dual drivers in Arduino shield and Raspberry Pi HAT form factors. Earlier this year, we brought the improved motor drivers to our Jrk G2 Motor Controllers with Feedback for those wanting to make their own closed-loop servo systems.

Now, the G2 motor driver technology is available on our Simple Motor Controllers as well. For the most part, this is not as big of a change as with the other G2 motor control products, but we did add a few nice features while maximizing backward compatibility. Key improvements over the originals include reverse voltage protection, configurable hardware current limiting, and the addition of an I²C interface for yet another control option—the others being USB, analog voltage, hobby RC servo interface, and asynchronous serial (UART). Additionally, the highest-power units (the SMC G2 18v25 and 24v19) use a four-layer board with double-sided assembly, which lets them be much smaller than their original SMC 18v25 and 24v23 counterparts:

The lower-power units have the exact same size and generally have the same connector locations as the original Simple Motor Controllers:

The most notable difference from a form factor and connection standpoint is the change from the USB mini-B connector on the older motor controllers to the micro-B connector on the G2 models. The following table shows the main specifications of all of the old and new Simple Motor Controllers:

# New products: Shunt Regulators

Posted by Jan on 1 November 2018

When I think of a robot, I usually picture a mobile robot, which generally means it is powered by a battery. Most of our motor controller products are built with that kind of bias in mind, too. But there are obviously many permanent installations that still call for motion, from 3D printers and robot arms to kinetic sculptures and motion simulators. And powering those can be complicated and expensive, with power supplies capable of powering bigger motors often costing more than the motors and the motor controllers. One difficulty is that power supplies are often not particularly good for absorbing the little pulses of power that motors and motor controllers sometimes send back out (typically when a motor is slowing down). The ramifications can be very bad since the supply voltages can quickly get destructively high when the current has nowhere to go. Many better power supplies have over-voltage protection, but that just means the power supply shuts down. While that’s better than expensive parts going up in smoke, it can still keep your project from functioning.

The simplest solution to the problem is often a transient voltage suppressor, or TVS, which is a big zener diode optimized for handling big current spikes. Unfortunately, TVS diodes typically do not have a tight enough tolerance for use with power supplies with over-voltage protection. For example, a 12V power supply might have 5% tolerance, meaning the output voltage could be as high as 12.6V, so the protection device must not kick in below 12.6V. If the over-voltage protection is triggered by a 15% deviation, any voltage spikes must be kept below 13.8V. Most basic TVSes do not have tight enough tolerances to ensure operation in that window.

So, we developed a shunt regulator that should help with that kind of scenario. A simplified schematic diagram of the shunt regulator is shown below. Basically, a circuit monitors the voltage and controls a MOSFET that allows current to flow through a shunt resistance that sets the maximum current the device can sink.

We offer the shunt regulators with a variety of voltage set points and shunt resistances. Available variations include fixed resistances and multi-turn potentiometers for the voltage set point, different shunt resistances for the load, and different power ratings for the shunt resistance (the higher-power versions have twenty more resistors populated on the back side of the board).

One version of the shunt regulator is populated with an especially high shunt resistance with minimal power rating; this unit is intended for use with an external shunt resistance:

The available versions are shown in the table below:

Voltage
13.2 V 26.4 V 33.0 V Fine-adjust LV Fine-adjust HV
Power 3 W #3780
32.8 Ω
9 W #3770
1.33 Ω
#3774
4.00 Ω
#3776
4.00 Ω
15 W #3771
1.50 Ω
#3775
2.80 Ω
#3777
4.10 Ω
#3778
1.50 Ω
#3779
4.10 Ω

This product is more for advanced users at this point since it can be difficult to determine how much power your motor is dumping back onto the power supply, but since we have the products working and several customers waiting to use them, we are going ahead with releasing them. We expect to develop additional resources and to put up verified regulator/motor controller combinations over time.

The basic regulators are quite inexpensive, and we are offering an introductory special as we are with all new products this year, so you might want to pick some up to play around with. The first hundred customers to use coupon code SHUNTREGS get 30% off on up to three units (per version).

# New products: D36V6x step-down regulators

Posted by Jan on 31 August 2018

Wrapping up our new product releases for the month and for the summer is our new D36V6x family of step-down voltage regulators. These small regulator modules support a large input voltage range and are a great alternative to old three-terminal linear voltage regulators that waste a lot of power and get really hot. These new regulators can take an input voltage anywhere from a few tenths of a volt over the set output voltage up through an absolute max of 50 V, and they can deliver up to 600 mA. We have them available in seven fixed voltage options and two adjustable versions:

You might notice that the board for the adjustable version shows a 2010 copyright year (the fixed version is an even smaller board, and we did not fit the year on there). That’s because these new regulators are actually old designs updated with new regulator chips that use the same package and pinout. The older products were our D24V3x and D24V6x families of regulators, which were based on the Texas Instruments LMR14203 and LMR14206 ICs. For the new D36V6x family, we are moving up to the newer LMR16006 regulator. This chip has several exciting new features that we think will make it our favorite general-purpose regulator for many of our products: higher maximum voltage, better low-dropout performance, and better quiescent current.

### Higher maximum voltage

The LMR16006 has a 60 V maximum input voltage, up from the 42 V of the LMR1420x parts. Even 42 V covered most of our typical applications, but it’s not quite enough for 36V nominal applications, which are getting more common. Our more advanced, integrated products such as motor controllers are often limited by some complex part or circuit, such as a motor driver, and we would like the overall operating range of the product not to be reduced by the regulator. Many stepper motor drivers, such as TI’s DRV8825 or the Toshiba TB67S249FTG and TB67S279FTG that we released carriers for in June, support maximum input voltages of 45 or 50 volts. It’s nice not to be limited by your regulator when you are making systems with those kinds of parts.

For our new D36V6x modules, we are limited to the 50 V maximum of the capacitors from Vin to ground. Unfortunately, capacitor options get a lot more restricted (and expensive) once we go beyond 50 V, so we decided to stick with our old boards so that we could continue to offer these regulator modules at a low price while still providing some substantial improvements. We might still make a new board with higher-voltage capacitors for those who would like to make full use of the regulator’s 60 V maximum. (For anyone thinking of just removing the caps and putting on your own external ones, you might also want to change the diode, which is also a 60 V part.)

### Better low-dropout performance

Having a higher maximum input voltage is nice, but often we’re trying to squeeze the most we can out of a dying battery, so it’s nice to have a low dropout, which is the voltage the regulator needs between the input and output. The older LMR1420x parts had an annoying quality of the dropout voltage going up as the load current went down. The newer LMR16006 has a nice, low dropout as the current goes down, so if you don’t need much current, you can get 5 V out with just 5.2 or 5.3 volts in. Here is a comparison of the dropout performance of the old and new regulators:

### Lower quiescent current

The new regulators also have much lower quiescent current, which is the current the regulator uses when it’s just sitting there and your load isn’t drawing anything. On the old regulators, the quiescent current was under 2 mA, and we did not characterize it beyond that. For these new regulators, it’s typically under 200 microamps, ten to twenty times better than the old regulators. I realize it’s not that amazing for modern regulators, but it’s nice to know that your low-cost, general-purpose regulator module isn’t wasting a lot of power.

Even when we put a new chip onto an old circuit board as I have described, we still test and characterize with different parts to get a good overall result. In the case of these regulators, where the circuit is quite simple, this phase of development is much more time consuming than laying out a circuit board. We build and test dozens of prototypes with different inductances, and even though you can’t see it in the pictures, we build the different voltage versions of the regulators with different inductors to get the best performance we can (within a given inductor type and size).

So how about getting a few to have around for general-purpose use on your next project? You can get one for just $3 as part of our introductory promotion using coupon code D36V6XINTRO, limited to the first 100 customers and to three per item (so you could get up to 27 regulators at that price if you get three of each voltage version). It’s always difficult for us to predict which versions will be how popular, so initial stock is limited, but we make these here in Las Vegas, so even if the version you want goes out of stock, you can backorder it with the promotional price, and we should be able to ship within a day or two. # New products: 1- and 31-channel QTR HD reflectance sensor arrays Posted by Jan on 31 August 2018 This week, we released what we expect to be the extremes of our new line of QTR HD reflectance sensor arrays, with two sizes of a single-sensor board on the small end and a massive 31-sensor array for the maximum size. This picture shows the relative sizes of the boards, along with some of the intermediate sizes we have available: We made the two single-sensor sizes because we could make good arguments for each one. Part of the point of doing a single-sensor board is to make it really small, so you can fit it into tight spaces. But “really small” means different things depending on the dimensions you care about. So we have one version that is only 5 mm (0.2") wide, with components on both sides of the PCB, and one version that is 7.5 mm (0.3") wide, with components on just one side. The 7.5 mm wide version is a little thinner and flatter because it doesn’t have parts on one side, can be used with a 3×1, single row connector, and costs slightly less because of the single-sided assembly. As I mentioned in some of my earlier posts (here and here) about this new line of sensor arrays, we are using two sensor types: more economical units we are calling “QTR”, and higher-performance units with lenses that we are calling “QTRX”. The main appeal of the QTRX sensors is that they can give the same readings at much lower IR emitter currents, which can really make a big difference for big sensor arrays. But if you crank up the current in those QTRX sensors, you can also get more distance. We did not do that on the QTRX arrays because the sensor modules leak light out the sides and interfere with each other when they are closely spaced, but with these single-channel boards, we are also making available the QTRX sensors with the higher 30 mA maximum emitter current, which allows for a range of up to about 8 cm (about 3 inches). We are calling these sensors QTRXL. This video (taken with an old camera that does not have as much IR filtering as most newer cameras) shows the IR light leakage around the side of the QTRX sensor module: I should point out that all of these new QTR modules offer variable brightness control by varying the current through the emitter using the control pin. However, if you want to take advantage of the maximum brightness and range, and have several sensors close to each other, you will need some barriers between them to prevent them from blinding each other (or just turn on one emitter at a time). The 31-sensor arrays are huge! Well, at least compared to the tiny single-sensor boards. The routing on those boards is quite complex because adjacent IR emitters are not just wired in series (because we want to have separate even/odd emitter control, plus the alternate density population options I discussed in this post), so we ended up having to go to a 4-layer PCB to route it. This did let us make the vertical dimension a little lower, so the board is just 16.5 mm tall, compared to the 20 mm board height for the versions with 15 and fewer sensors. The 31-channel board is also 0.062" (1.6 mm) thick, compared to the thinner 0.040" (1 mm) boards we use for the lower channel counts. You can compare all the dimensions of the various boards in the detailed dimension diagram (1MB pdf). The sixteen new boards we released this week brings the total available in this new QTR HD product line to 40. You can see the options neatly summarized in the tables below to pick the best array for your application. QTR sensors 2.9 V to 5.5 V; 30 mA max LED current(1); 5 mm optimal range Board width Configuration Max board current(2) Max range Output type Name 1-piece price 5.0 mm 1 sensor (HD) 32 mA 30 mm analog QTR-HD-01A$1.79
RC (digital) QTR-HD-01RC
7.5 mm 1 sensor (MD)
32 mA 30 mm analog QTR-MD-01A $1.61 RC (digital) QTR-MD-01RC 10.2 mm 4 mm × 2 32 mA 30 mm analog QTR-HD-02A$2.12
RC (digital) QTR-HD-02RC
17.0 mm 4 mm × 4
62 mA 40 mm analog QTR-HD-04A $3.26 RC (digital) QTR-HD-04RC 29.0 mm 8 mm × 4 62 mA 40 mm analog QTR-MD-04A$3.44
RC (digital) QTR-MD-04RC
4 mm × 7
125 mA 40 mm analog QTR-HD-07A $5.40 RC (digital) QTR-HD-07RC 61.0 mm 8 mm × 8 125 mA 40 mm analog QTR-MD-08A$6.39
RC (digital) QTR-MD-08RC
4 mm × 15
250 mA 50 mm analog QTR-HD-15A $10.82 RC (digital) QTR-HD-15RC 125.0 mm 4 mm × 31 495 mA 50 mm analog QTR-HD-31A$21.66
RC (digital) QTR-HD-31RC
QTRX sensors
2.9 V to 5.5 V; 3.5 mA max LED current(1); 10 mm optimal range
Board
width
Configuration Max board
current(2)
Max range Output
type
Name 1-piece
price
5.0 mm 1 sensor (HD)
5 mA 30 mm analog QTRX-HD-01A $2.17 RC (digital) QTRX-HD-01RC 7.5 mm 1 sensor (MD) 5 mA 30 mm analog QTRX-MD-01A$1.99
RC (digital) QTRX-MD-01RC
10.2 mm 4 mm × 2
5 mA 30 mm analog QTRX-HD-02A $2.88 RC (digital) QTRX-HD-02RC 17.0 mm 4 mm × 4 9 mA 40 mm analog QTRX-HD-04A$4.78
RC (digital) QTRX-HD-04RC
29.0 mm 8 mm × 4
9 mA 40 mm analog QTRX-MD-04A $4.96 RC (digital) QTRX-MD-04RC 4 mm × 7 17 mA 40 mm analog QTRX-HD-07A$8.06
RC (digital) QTRX-HD-07RC
61.0 mm 8 mm × 8
17 mA 40 mm analog QTRX-MD-08A $9.43 RC (digital) QTRX-MD-08RC 4 mm × 15 34 mA 50 mm analog QTRX-HD-15A$16.52
RC (digital) QTRX-HD-15RC
125.0 mm 4 mm × 31
68 mA 50 mm analog QTRX-HD-31A $33.44 RC (digital) QTRX-HD-31RC QTRXL sensors 2.9 V to 5.5 V; 30 mA max LED current(1); 20 mm optimal range Board width Configuration Max board current(2) Max range Output type Name 1-piece price 5.0 mm 1 sensor (HD) 32 mA 80 mm analog QTRXL-HD-01A$2.17
RC (digital) QTRXL-HD-01RC
7.5 mm 1 sensor (MD)

# New product: high-density QTR reflectance sensor arrays

Posted by Jan on 31 July 2018
Tags: new products

I am excited to announce the first of a new line of reflectance sensor arrays that feature a high-density 4-mm pitch and dimmable IR emitter brightness control. In addition to versions with our familiar IR emitter/phototransistor pair modules without lenses, which we will keep calling “QTR,” we have versions with a higher-performance sensor with lenses on the IR emitter and phototransistor, which we are calling “QTRX.” These higher-performance sensors allow similar performance at a much lower IR LED current, which can really start adding up at higher channel counts. (High-brightness, “QTRXL” versions of these boards are coming soon, too.)

These new sensor arrays also feature LED brightness control that is independent of the supply voltage (which can be 2.9 V to 5.5 V) and separate controls for the odd-numbered LEDs and the even-numbered LEDs, which gives you extra options for detecting light reflected at various angles. As with our older QTR sensors, we are offering these in “A” versions with analog voltage outputs and “RC” versions that can be read with a digital I/O line on a microcontroller by first setting the line high and then releasing it and timing how long it takes for the voltage to get pulled to the logic low threshold:

This announcement therefore covers four total new products:

As with all our new products this year, we are offering a special introductory promotion, and this one is for half off up to three of each sensor type, limited to the first 100 customers using coupon code QTRHD07INTRO.

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