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New products: RoboClaw Solo 30A and 60A Motor Controllers
We are now carrying Ion Motion Control’s line of single-channel RoboClaws, the Solo 30A and Solo 60A. These versatile, high-power motor controllers have nearly all the same features and performance capabilities as their dual-channel 2×30A and 2×60A counterparts, just with one fewer motor channel. Just like the rest of the RoboClaw family, the Solos support a variety of interfaces, including USB serial, TTL serial, RC hobby servo pulses, and analog voltages, and integrated quadrature decoders enable closed-loop position or velocity control.
Unlike our selection of dual-channel RoboClaws, the Solos also feature a rugged, all-metal case that protects the driver while simultaneously serving as a heat sink, and they have four 12 AWG unterminated leads for supplying power and connecting a motor.
The following table shows our full updated offering of RoboClaw motor controllers:
Solo 30A |
Solo 60A |
2x7A |
2x15A |
2x30A |
2x45A ST 2x45A |
2x60A |
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Motor channels: | 1 | 2 | |||||
Operating voltage: | 6 V to 34 V | 6 V to 34 V | |||||
Continuous output current: | 30 A | 60 A | 7.5 A | 15 A | 30 A | 45 A | 60 A |
Peak output current: | 60 A | 120 A | 15 A | 30 A | 60 A | 60 A | 120 A |
5V BEC max current: | 1.2 A | 1.2 A (V5B or later) | 3 A | ||||
Size | 60 × 32.5 × 23.5 mm | 48 × 42 × 17 mm | 74 × 52 × 17 mm | 100 × 86 × 25 mm | |||
Weight: | 130 g | 18 g | 60 g | 295 g | |||
Price: | $89.95 | $119.95 | $114.95 | $129.95 | $169.95 | $191.95 | $199.95 |
New product: Tic T500 USB Multi-Interface Stepper Motor Controller
Our Tic stepper motor controllers are pretty awesome, and the new Tic T500 we released today should make stepper motors even more accessible for your next project. This latest version features a broad 4.5 V to 35 V operating range that covers everything from small 2-cell lithium battery packs up to 24 V batteries or power supplies while costing just $20 in single-piece quantities. This video gives you a quick overview of what the Tic stepper motor controllers offer:
The Tics make basic speed or position control of a stepper motor easy, with support for six high-level control interfaces:
- USB for direct connection to a computer
- TTL serial operating at 5 V for use with a microcontroller
- I²C for use with a microcontroller
- RC hobby servo pulses for use in an RC system
- Analog voltage for use with a potentiometer or analog joystick
- Quadrature encoder input for use with a rotary encoder dial, allowing full rotation without limits (not for position feedback)
The Tic T500 is available with connectors soldered in or without connectors soldered in. Here is a handy comparison chart with all three Tic stepper motor controllers:
Tic T500 |
Tic T834 |
Tic T825 |
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Operating voltage range: | 4.5 V to 35 V(1) | 2.5 V to 10.8 V | 8.5 V to 45 V(1) |
Max current per phase (no additional cooling): |
1.5 A | 1.5 A | 1.5 A |
Microstep resolutions: | full half 1/4 1/8 |
full half 1/4 1/8 1/16 1/32 |
full half 1/4 1/8 1/16 1/32 |
Automatic decay selection: | |||
Price (connectors not soldered): | $29.95 | $39.95 | $39.95 |
Price (connectors soldered): | $31.95 | $41.95 | $41.95 |
1 See product pages and user’s guide for operating voltage limitations.
Basically, the new T500 does not offer the finer microstep resolutions of the T834 and T825, and the T834 supports very low operating voltages while the T825 supports higher operating voltages.
For those of you interested in more of the details of the stepper motor driver, the Tic T500 uses the new MP6500 from MPS, which we also offer on some low-cost MP6500 breakout boards with analog (small trimmer potentiometer) and digital (via PWM) current limit setting options.
In keeping with the tradition we started this year, we are offering an extra discount for the first customers, to help share in our celebration of releasing a new product. The first hundred customers to use coupon code T500INTRO can get up to two units for just $15.53! (Click to add the coupon code to your cart.) And we’ll even cover the shipping in the US! Note that this introductory offer applies only to the units without connectors soldered in.
New product: A-Star 328PB Micro
Today we are releasing our newest A-Star programmable controller, the A-Star 328PB Micro. It is basically our version of the ubiquitous Arduino Pro Mini type products, but with the newer ATmega328PB microcontroller. The board itself is pretty straightforward (though the updated AVR is exciting), so the main thing I want to share in this post is our history with the Atmel ATmega328PB microcontrollers (this was before Microchip acquired Atmel) and how this product would not have existed without our lower-cost manufacturing initiative that I have been discussing.
We have been using the ATmega8, and then the ATmega48, ATmega168, and ATmega328P, since 2004 in many of our user-programmable products because of their versatility and excellent free compiler support (which also made Arduino possible). We first heard about the ATmega328PB in early 2014. The product kept being delayed, and I did not get a quote for them until October 2015. I ordered a reel right away; it arrived in March 2016. Over those two years, we put our AVR-related efforts into the ATmega32U4, releasing several A-Star 32U4 programmable controllers and using it on robots like the Zumo 32U4. The ATmega32U4 was a superior part with native USB and more I/O lines, making it a better fit for many of our applications. By the time we finally got the ATmega328PB parts, we had the A-Star 32U4 Micro available for just $12.75, making it less exciting to put effort into a lower-performance product that might end up costing almost the same amount.
Original ATmega168-based Baby Orangutan robot controller from 2005 (left) next to A-Star 32U4 Micro boards. |
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The new manufacturing equipment I ordered in the fall of 2017, along with the availability of our latest AVR programmer, brought attention back to the feasibility of a basic ATmega328PB carrier. I was hesitant to put effort into a product where we could not offer something substantially more compelling than what was already available. Despite the ATmega328PB being out in the wild for almost two years, it still had not really made it into many Arduino products, so I thought that perhaps we could offer something there. But more importantly, I wanted to see how low we could price it. I was aware of Arduino Pro Mini clones available on eBay and the AliExpress-type sites for under $3. Most official Arduino Pro Mini type products cost more like $10. For this project to be worthwhile, I wanted to get under $5.
It turns out we had to squeeze quite a bit just to get to the upper limit of that “under $5” goal, and so we are releasing this product at a unit retail price of $4.95. It’s not the under-$3 you can find for the absolute cheapest clones, but if you get the A-Star 328PB Micro from us, you are getting a well-supported, well-made product (each unit is 100% automatically visually inspected and 100% functionally tested) and supporting a company that is doing more than just copying products that are already out there.
It is my hope that by being able to offer the A-Star 328PB Micro for under $5, we are offering something meaningful, giving you a new option for general-purpose controllers at the price of a cheap lunch. I am interested to hear what you think. Is the 328PB interesting when you can get USB for not much more? Is the price low enough for you to buy from us instead of getting it from China?
We are offering the A-Star 328PB Micro in four voltage and frequency combinations:
- 5 V, 16 MHz (blue power LED)
- 5 V, 20 MHz (red power LED) Note: See item-specific page for speed warning.
- 3.3 V, 8 MHz (green power LED)
- 3.3 V, 12 MHz (yellow power LED)
A-Star 328PB Micro pinout diagram. |
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The A-Star 328PB Micro provides access to all 24 I/O lines of the microcontroller and ships with an Arduino-compatible serial bootloader; you can also use an AVR in-system programmer (ISP) for access to the entire chip. We recommend our USB AVR Programmer v2, which supports both programming interfaces and can be configured to run at either 3.3 V or 5 V.
Last but not least, we are continuing our plan of offering new products at the highest quantity price break at single unit quantities as an introductory celebration. That means that for the first 100 customers, you can get an A-Star 328PB Micro for just $3.87! (Must use coupon code AS328PBINTRO; click to add the coupon code to your cart.)
While we assemble (and design and document and ship and support) the boards here in Las Vegas, we still get the bare PC boards from China, where they are currently on holiday celebrating Chinese New Year. That is constraining how many units we can make at the moment, so we are limiting shipments to 5 units per customer. However, the introductory coupon has no quantity limit, and you can order more than five at that price if you would like. Backordered units are likely to ship within a few weeks.
New Pololu Balboa T-Shirts!
Our new Balboa T-shirts are here! They feature our latest robot, the Balboa 32U4 balancing robot, within an enlarged outline of the 43-tooth gear option for the Balboa gearbox, accompanied by our call to “Engage Your Brain”. These pre-shrunk cotton shirts are available in several colors (navy blue, cardinal red, or black) and a range of youth and adult sizes.
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New products: MP6500 Stepper Motor Driver Carriers
We are excited to expand our colorful selection of stepper motor drivers with carrier boards for the brand new MPS MP6500 stepper motor driver!
Monolithic Power Systems’ MP6500 can drive a bipolar stepper motor from a 4.5 V to 35 V supply with up to 1/8-step microstepping. On our four-layer, 2 oz copper carrier boards, the MP6500 can deliver up to approximately 1.8 A per phase continuously without a heat sink or forced air flow, making this new module the highest-current stepper motor driver we carry among all the ones that share this form factor.
14 March 2018 Update: After further testing of more units, our initial characterization of the maximum continuous current capability was too high, so we have lowered it to 1.5 A. Please keep in mind that the exact maximum current you can get out of the driver at a given temperature will depend on your supply voltage and stepper motor characteristics.
Unlike most other stepper motor drivers, the MP6500 features internal current sensing, which allows it to measure the motor’s coil current even during the off period of the PWM cycle. Combined with its automatic decay selection, this allows it to regulate the current especially accurately to produce smoother motion and higher speeds, as shown in the below oscilloscope capture from the MPS application note AN120 (1MB pdf).
Compare this with waveforms from a stepper driver that uses a more typical method of peak current control:
In addition to a version with potentiometer current control like most of our other stepper motor drivers, we also offer the MP6500 on a board with digital current control. This second version enables a microcontroller to dynamically set the current limit in steps of 0.5 A (up to a maximum of 2 A) by simply driving one or two inputs low. Alternatively, supplying an analog voltage or PWM signal allows finer control of the limit within the 0 to 2 A range.
Introductory special: just $2.97 each! Must use coupon code MP6500INTRO, limited to first 200 customers, limit 5 per customer.
Want to move heavy loads? We've got the linear actuator for you!
We have expanded our selection of Glideforce linear actuators from Concentric International to include their industrial-duty and medium duty series as steps up in power from their light-duty series that we have been offering for many years now.
The medium-duty actuators are available in five different stroke lengths ranging from 4″ to 12″ and with or without feedback potentiometers, and they have a dynamic load rating of 225 lb, which means they can handle twice the load of their light-duty counterparts:
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The industrial-duty actuators are real monsters compared to the medium-duty and light-duty units. The versions with an acme screw drive can handle dynamic loads up to 550 lb, and the versions with a ball screw drive (which is much more efficient than an acme screw) can handle dynamic loads up to a 1000 lb. Each drive option is available in six different stroke lengths ranging from 4″ to 24″ and with or without feedback potentiometers:
The following lets you compare all of our Glideforce linear actuator options:
Actuator Type |
Max Dynamic Load |
No-Load Speed @ 12 V |
Current Draw @ 12 V |
Nominal Stroke Length |
With Feedback | Without Feedback | Approx. Weight |
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Light-Duty (LD) |
15 kgf [34 lbs] |
4.4 cm/s [1.7″/s] |
1.2 A – 3.2 A |
4″ | LACT4P-12V-05 | LACT4-12V-05 | 1.3 kg |
12″ | LACT12P-12V-05 | LACT12-12V-05 | 1.6 kg | ||||
50 kgf [110 lbs] |
1.5 cm/s [0.57″/s] |
2″ | LACT2P-12V-20 | LACT2-12V-20 | 1.2 kg | ||
4″ | LACT4P-12V-20 | LACT4-12V-20 | 1.3 kg | ||||
6″ | LACT6P-12V-20 | LACT6-12V-20 | 1.4 kg | ||||
8″ | LACT8P-12V-20 | LACT8-12V-20 | 1.5 kg | ||||
10″ | LACT10P-12V-20 | LACT10-12V-20 | 1.5 kg | ||||
12″ | LACT12P-12V-20 | LACT12-12V-20 | 1.6 kg | ||||
Medium-Duty (MD) |
100 kgf [225 lbs] |
1.5 cm/s [0.58″/s] |
1.1 A – 4.6 A |
4″ | MD122004-P | MD122004 | 1.1 kg |
6″ | MD122006-P | MD122006 | 1.2 kg | ||||
8″ | MD122008-P | MD122008 | 1.3 kg | ||||
10″ | MD122010-P | MD122010 | 1.4 kg | ||||
12″ | MD122012-P | MD122012 | 1.5 kg | ||||
Industrial-Duty (ID) with Acme screw drive |
250 kgf [550 lbs] |
1.7 cm/s [0.66″/s] |
2.4 A – 13.2 A |
4″ | LACT4-500APL | LACT4-500AL | 4.2 kg |
6″ | LACT6-500APL | LACT6-500AL | 4.4 kg | ||||
8″ | LACT8-500APL | LACT8-500AL | 4.7 kg | ||||
12″ | LACT12-500APL | LACT12-500AL | 5.3 kg | ||||
18″ | LACT18-500APL | LACT18-500AL | 6 kg | ||||
24″ | LACT24-500APL | LACT24-500AL | 7 kg | ||||
Industrial-Duty (ID) with ball screw drive |
450 kgf [1000 lbs] |
1.7 cm/s [0.66″/s] |
2.4 A – 13.2 A |
4″ | LACT4-1000BPL | LACT4-1000BL | 4.6 kg |
6″ | LACT6-1000BPL | LACT6-1000BL | 4.9 kg | ||||
8″ | LACT8-1000BPL | LACT8-1000BL | 5.1 kg | ||||
12″ | LACT12-1000BPL | LACT12-1000BL | 5.6 kg | ||||
18″ | LACT18-1000BPL | LACT18-1000BL | 6.5 kg | ||||
24″ | LACT24-1000BPL | LACT24-1000BL | 7.4 kg |
Note that we are currently out of stock of many of the industrial-duty versions, but we will be getting more as Concentric makes them available. For units where the expected lead time is several months, we have disabled backorders; please contact us if you are interested in placing an order now for one of those units.
To see all of our linear actuators, visit our linear actuator category.
New adjustable voltage regulators with multi-turn fine adjustment
I am excited to announce our first voltage regulators with multi-turn trimmer potentiometers! I have wanted to add multi-turn pots to our products for a long time, but the problem has been that they are really expensive. They also tend to be quite big, at least compared to many of our boards, which we try to keep compact, and the smaller, surface-mounted ones are especially expensive. My latest round of looking for lower-cost options did not pan out, but I decided to just give it a try with the expensive parts.
The new S9V11x regulators that feature these potentiometers are buck-boost regulators that can output a voltage that is lower, the same, or higher than the input voltage. There are also versions with a multi-turn pot for adjusting the undervoltage cutoff threshold, so that if you use these with batteries, you can prevent overdischarging them. With twelve turns of adjustment available, it’s much easier to precisely set the voltages on the modules than with the single-turn potentiometers we have used on other adjustable regulators.
The output and cutoff multi-turn adjustment potentiometers on the S9V11x voltage regulators. |
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While I have been talking mostly about the potentiometers, the main regulator is pretty magical, too, giving you quite a bit of power over a broad operating input range in a small size.
Typical maximum continuous output current of Step-Up/Step-Down Voltage Regulator S9V11x |
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Our stock products are available in several combinations of adjustable and fixed output voltage and cutoff. If you have a higher-volume application, we can make them with fixed voltages wherever you need them. You could initially prototype your design with the adjustable version and then get fixed ones made once you know exactly what voltage you need.
Regulator | Input (V) | Output (V) | Low-voltage cutoff | Size | Price | |
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#2868 S9V11MACMA | 2* – 16 | 2.5 – 9 (fine-adjust) | fine-adjust | 0.50″ × 0.60″ × 0.25″ | $13.95 | |
#2869 S9V11MA | 2.5 – 9 (fine-adjust) | – | $10.95 | |||
#2870 S9V11F5S6CMA | 5 (6 V selectable) | fine-adjust | $10.95 | |||
#2871 S9V11F3S5CMA | 3.3 (5 V selectable) | fine-adjust | $10.95 | |||
#2872 S9V11F3S5 | 3.3 (5 V selectable) | – | 0.50″ × 0.60″ × 0.17″ | $7.95 | ||
#2873 S9V11F3S5C3 | 3.3 (5 V selectable) | 3 V (fixed) | $7.95 | |||
#2836 S9V11F5 | 5 | – | 0.30″ × 0.45″ × 0.17″ | $8.95 | ||
* The regulator has a minimum start-up voltage of 3 V, but it can operate down to 2 V after startup. It is disabled when the input voltage is below the low-voltage cutoff. |
I am very interested to see what people think of the multi-turn adjustment feature. If these new regulators sell decently or customers ask for it, we will add the multi-turn potentiometers to our other regulator offerings. Is the extra expense worth it? Or do you know of a good, low-cost, multi-turn potentiometer we could consider for future products like this?
Our 20D gearmotors with long-life carbon brushes are now available with extended motor shafts
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Last month when we introduced versions of our 20D gearmotors with long-life carbon brushes, we mentioned units with extended motor shafts were in the works. Well, I’m happy to announce that option is now available for both the 12V CB and 6V CB 20D gearmotors, making it possible to use them with encoders like our magnetic encoder kit. The following table shows our full selection of 20D gearmotors, which has now grown to 72 options:
Rated Voltage |
Brush Type | Stall Current @ Rated Voltage |
No-Load Speed @ Rated Voltage |
Approximate Stall Torque @ Rated Voltage |
Single-Shaft (Gearbox Only) |
Dual-Shaft (Gearbox & Motor) |
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12 V | long-life carbon (CB) |
1.6 A | 570 RPM | 26 oz-in | 25:1 12V CB | 25:1 12V CB dual shaft |
450 RPM | 33 oz-in | 31:1 12V CB | 31:1 12V CB dual shaft | |||
225 RPM | 58 oz-in | 63:1 12V CB | 63:1 12V CB dual shaft | |||
180 RPM | 75 oz-in | 78:1 12V CB | 78:1 12V CB dual shaft | |||
140 RPM | 85 oz-in | 100:1 12V CB | 100:1 12V CB dual shaft | |||
110 RPM | 110 oz-in | 125:1 12V CB | 125:1 12V CB dual shaft | |||
90 RPM | 130 oz-in | 156:1 12V CB | 156:1 12V CB dual shaft | |||
72 RPM | 160 oz-in | 195:1 12V CB | 195:1 12V CB dual shaft | |||
57 RPM | 200 oz-in | 250:1 12V CB | 250:1 12V CB dual shaft | |||
45 RPM | 250 oz-in | 313:1 12V CB | 313:1 12V CB dual shaft | |||
36 RPM | 290 oz-in | 391:1 12V CB | 391:1 12V CB dual shaft | |||
29 RPM | 350 oz-in | 488:1 12V CB | 488:1 12V CB dual shaft | |||
6 V | long-life carbon (CB) |
2.9 A | 590 RPM | 22 oz-in | 25:1 6V CB | 25:1 6V CB dual shaft |
470 RPM | 28 oz-in | 31:1 6V CB | 31:1 6V CB dual shaft | |||
230 RPM | 54 oz-in | 63:1 6V CB | 63:1 6V CB dual shaft | |||
190 RPM | 62 oz-in | 78:1 6V CB | 78:1 6V CB dual shaft | |||
150 RPM | 72 oz-in | 100:1 6V CB | 100:1 6V CB dual shaft | |||
120 RPM | 87 oz-in | 125:1 6V CB | 125:1 6V CB dual shaft | |||
93 RPM | 110 oz-in | 156:1 6V CB | 156:1 6V CB dual shaft | |||
75 RPM | 130 oz-in | 195:1 6V CB | 195:1 6V CB dual shaft | |||
60 RPM | 170 oz-in | 250:1 6V CB | 250:1 6V CB dual shaft | |||
46 RPM | 220 oz-in | 313:1 6V CB | 313:1 6V CB dual shaft | |||
37 RPM | 260 oz-in | 391:1 6V CB | 391:1 6V CB dual shaft | |||
30 RPM | 310 oz-in | 488:1 6V CB | 488:1 6V CB dual shaft | |||
6 V | precious metal |
2.9 A | 590 RPM | 22 oz-in | 25:1 6V | 25:1 6V dual-shaft |
470 RPM | 28 oz-in | 31:1 6V | 31:1 6V dual-shaft | |||
230 RPM | 54 oz-in | 63:1 6V | 63:1 6V dual-shaft | |||
190 RPM | 62 oz-in | 78:1 6V | 78:1 6V dual-shaft | |||
150 RPM | 72 oz-in | 100:1 6V | 100:1 6V dual-shaft | |||
120 RPM | 87 oz-in | 125:1 6V | 125:1 6V dual-shaft | |||
93 RPM | 110 oz-in | 156:1 6V | 156:1 6V dual-shaft | |||
75 RPM | 130 oz-in | 195:1 6V | 195:1 6V dual-shaft | |||
60 RPM | 170 oz-in | 250:1 6V | 250:1 6V dual-shaft | |||
46 RPM | 220 oz-in | 313:1 6V | 313:1 6V dual-shaft | |||
37 RPM | 260 oz-in | 391:1 6V | 391:1 6V dual-shaft | |||
30 RPM | 310 oz-in | 488:1 6V | 488:1 6V dual-shaft |
Note: Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. In order to avoid damaging the gearbox, we recommend keeping continuously applied loads under 50 oz-in (3.5 kg*cm) for the versions with precious metal brushes and under 70 oz-in (5 kg-cm) for the versions with carbon brushes (the ones with “CB” in the name). Stalls can also result in rapid (potentially on the order of a second) thermal damage to the motor windings and brushes, especially for motors like this that can deliver a lot of power for their size; a general recommendation for brushed DC motors is to limit continuous current to approximately 25% of the stall current.
Now for Raspberry Pi too: Dual G2 High-Power Motor Drivers
As Jan promised yesterday, our new dual motor drivers are now also available as Raspberry Pi expansion boards! The Dual G2 High-Power Motor Drivers for Raspberry Pi feature two discrete MOSFET H-bridges on a board designed to plug directly into a Raspberry Pi (Model B+ or newer), and they also include an integrated 5 V, 2.5 A switching step-down regulator that allows a single power supply to power both the motors and the Raspberry Pi. We provide a Python library for Raspberry Pi to make it easy to get started using the drivers.
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As with the Arduino shield (or standalone) versions, two different PCBs are used for these drivers: the black board has 5×6 mm MOSFETs and the red board has 3×3 mm MOSFETs. Again, each board is available with 30 V or 40 V MOSFETs for a total of four options:
Dual G2 High- Power Motor Driver 18v22 for Raspberry Pi |
Dual G2 High- Power Motor Driver 18v18 for Raspberry Pi |
Dual G2 High- Power Motor Driver 24v18 for Raspberry Pi |
Dual G2 High- Power Motor Driver 24v14 for Raspberry Pi |
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Absolute max input voltage: |
30 V | 36 V* | ||
Max nominal battery voltage: |
18 V | 28 V | ||
Max continuous current per channel: |
22 A | 18 A | 18 A | 14 A |
Default active current- limiting threshold: |
60 A | 50 A | 40 A | |
Available with connectors installed? |
No | Yes | No | Yes |
* 40 V if regulator is disconnected
Unlike the Arduino, the Raspberry Pi does not have analog inputs, so there isn’t an easy way to do current sensing with these boards. However, the current sensing pins are exposed for advanced users who might want to add an external ADC or otherwise make use of the current sense feedback.
Until now, our motor driver offerings for the Raspberry Pi have been limited to our dual MC33926 and DRV8835 add-on boards, which handle much less current. One of our other favorite integrated motor drivers, the VNH5019, would have been a nice step up in power from the MC33926, but it has one big downside…literally. Its footprint measures around 17 mm by 19 mm, and you can see that on our dual VNH5019 Arduino shield, the two driver ICs take up most of the width of the board:
Pololu dual VNH5019 motor driver shield for Arduino. |
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We try to make our Raspberry Pi expansion boards conform to the HAT (Hardware Attached on Top) mechanical specification when we can, and that spec recommends including a slot in the middle of the board to accommodate a flex cable plugging into the Raspberry Pi’s camera connector.
Raspberry Pi HAT mechanical specification drawing. |
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Combined with the cutout for the other flex connector, this space limitation means that it would be difficult—if not impossible—to make a VNH5019 motor driver expansion board for the Raspberry Pi that is not annoyingly obstructive. So we are excited that the G2 design, with its discrete MOSFET H-bridges, provided enough layout flexibility for us to create these high-power dual motor driver expansions without making such compromises. We hope that they will open up new possibilities for bigger and more powerful Raspberry Pi robots!
New product: Dual G2 High-Power Motor Drivers
We sell a lot of motor drivers, which makes sense since you usually need motors to build robots, and motor drivers tend to be the kind of product you cannot really build yourself on a breadboard. One of our more popular products is the dual VNH5019 shield for the Arduino:
Pololu dual VNH5019 motor driver shield, assembled and connected to an Arduino Uno R3. |
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That product is based on ST’s massive VNH5019 motor driver chip, which is a successor to the VNH3SP30 driver we initially started selling back in 2005:
Older version of the High-Current Motor Driver Carrier. |
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When I first heard of the chip (at one of the first LVBots meetings), it seemed like someone must have misremembered the spec since it was inconceivable for a single integrated chip to deliver 30 amps. And to some extent, that was valid—you would have to do a lot of extra thermal management work to get 30 A out of that chip without it overheating. But the chip really could do in excess of 10 A, which was still amazing; the real limitation was in voltage, especially if you tried to use PWM at any moderate frequency. The VNH2SP30 was better about PWM frequency, letting us get to 20 kHz, but it had an upper operating limit of 16 V. The VNH5019 raised this to 24 V, getting us tantalizingly close to the 24V rail many would like to use. The problem is that 24 V is the limit, and we really need to be able to operate higher than that to account for the usual variations in nominally 24V power setups.
As far as I know, there is no integrated circuit that can deliver over ten amps at 24 V nominal (i.e. at least 30 V max); for that kind of power, you need to go to H-bridges with discrete MOSFETs. We have had those as stand-alone products for a while, too. But those still leave you with a lot of wiring to do if you want to drive two motors, which is typically the minimum for a mobile robot. The new product family we just released makes that easy by providing two high-power motor drivers in one Arduino shield-type package:
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As you can see from the pictures, the main difference in these Dual G2 High-Power Motor Driver Shields is in the MOSFETs: the white boards have larger, 5×6mm MOSFETs, and the blue boards have smaller, 3×3mm MOSFETs. These correspond to the two versions of the individual drivers:
Pololu G2 High-Power Motor Driver 24v21 and 24v13. |
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(The higher-power version on the left has the MOSFETs on the back side of the board.) We also offer each board with 30V and 40V MOSFETs, for four total options. The new dual motor drivers perform similarly to our single-channel G2 units, and like the single channel carriers, all of these dual drivers feature current sensing and an adjustable current limit that could be used to detect and protect against stall conditions. These are the individual performance points:
Dual G2 High- Power Motor Driver 18v22 Shield |
Dual G2 High- Power Motor Driver 18v18 Shield |
Dual G2 High- Power Motor Driver 24v18 Shield |
Dual G2 High- Power Motor Driver 24v14 Shield |
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Absolute max input voltage: |
30 V | 40 V | ||
Max nominal battery voltage: |
18 V | 28 V | ||
Max continuous current per channel: |
22 A | 18 A | 18 A | 14 A |
Default active current- limiting threshold: |
60 A | 50 A | 40 A | |
Current sense output: |
10 mV/A | 20 mV/A |
For drivers like these, power (heat) dissipation is generally the limiting factor. The copper area around the MOSFETs on both the white and blue versions of the drivers are about the same, so the lower-current blue units perform better then their smaller single channel G2 counter-parts, while the higher current white drivers do worse than the smaller single channel G2 carriers (which also use four layer PCBs for better performance). The power ratings we provide are the maximums without additional heat sinking or air flow and at room temperature. Please note that the boards will be extremely hot at those maximum currents, and the available current will be lower if the ambient temperature is higher.
Since many Arduino boards do not support higher input voltages, the new dual drivers also incorporate a 1A switching regulator so that a single higher-voltage supply can power the motors and Arduino. We have an Arduino library to help you get up and running quickly. And for those who want to use the board without an Arduino, all of the motor control connections are also brought out to a row of 0.1″ headers on one side of the board.
(And for those of you wanting to use this kind of driver with a Raspberry Pi, we have a Raspberry Pi HAT form-factor version coming soon!)