Posts by Claire (Page 2)

You are currently viewing a selection of posts from the Pololu Blog. You can also view all the posts.

Claire's line following robot: Oddish

Posted by Claire on 7 May 2015
Claire's line following robot: Oddish

A few weeks ago the local robotics club, LVBots, hosted a line following competition here at Pololu, and like many of the engineers here, I built a robot, which I named Oddish, for the competition. I really only started seriously working on my robot about a week before the competition, so when I made the final decisions about what components to use I aimed for simplicity. In the last year we have come out with several A-Star microcontroller boards that include switching regulators, so I thought it would be fun and simple to make a line follower using an A-Star as the brain and its built-in 5 V regulator to power all the other components. I chose the A-Star 32U4 Mini LV for its operating voltage range and size. Continued…

Video: Setting the Current Limit on Pololu Stepper Motor Driver Carriers

Posted by Claire on 14 April 2015

One of my many roles here at Pololu is overseeing technical support, and I have seen countless cases of customers who have problems with their stepper motor systems because they have not properly set the current limit on their stepper motor driver. To address the issue, we have made a new video that demonstrates how to set the current limit on our stepper motor driver carriers. The video also provides helpful tips and points out a few common pitfalls.

A DRV8825 carrier is used for the demonstration, but the video also applies to our A4988, DRV8824, and DRV8834 stepper motor driver carriers. In the demo, signals for the driver are provided by an Arduino-compatible A-Star 32U4 Prime SV. Here is a simplified version of the Arduino code from the video that can be used to step a motor in both directions:

/* Simple step test for Pololu stepper motor driver carriers 
This code can be used with the A4988, DRV8825, DRV8824, and 
DRV8834 Pololu stepper motor driver carriers.  It sends a pulse 
every 500 ms to the STEP pin of a stepper motor driver that is 
connected to pin 2 and changes the direction of the stepper motor
every 50 steps by toggling pin 3. */

#define STEP_PIN 2
#define DIR_PIN 3

bool dirHigh;

void setup()
  dirHigh = true;
  digitalWrite(DIR_PIN, HIGH);
  digitalWrite(STEP_PIN, LOW);
  pinMode(DIR_PIN, OUTPUT);
  pinMode(STEP_PIN, OUTPUT);

void loop()
  // Toggle the DIR pin to change direction.
    dirHigh = false;
    digitalWrite(DIR_PIN, LOW);
    dirHigh = true;
    digitalWrite(DIR_PIN, HIGH);

  // Step the motor 50 times before changing direction again.
  for(int i = 0; i < 50; i++)
    // Trigger the motor to take one step.
    digitalWrite(STEP_PIN, HIGH);
    digitalWrite(STEP_PIN, LOW);

GPS puzzle box

Posted by Claire on 18 March 2015

Forum user Bob Day shared his GPS puzzle box, which uses an A-Star 32U4 Micro, USGlobalSat EM-506 GPS Receiver, servo, and LCD to open a box only at a specific location. It also uses our S7V8F5 step-up/step-down regulator to provide power the A-Star and GPS module. In his post, Bob says that he got the idea from Mikal Hart’s “Reverse Geocache Puzzle Box”, which you can see in action in this video.

Top of GPS puzzle box by forum user Bob Day.

Pictures, connections, and the code used for the box can be found in Bob’s forum post.

New product: iMAX B6AC V2 Balance Charger and Discharger

Posted by Claire on 16 January 2015
Tags: new products

We have carried the iMAX B6AC charger from SkyRC for many years and often use it to charge batteries for our own projects and robot contests, so we are happy to now be carrying the upgraded iMAX B6AC V2 Balance Charger and Discharger. Both versions of the iMAX B6AC are capable of charging or discharging NiMH, NiCd, Pb, LiPo, Li-ion, and LiFe batteries and can be powered either from AC mains power or a DC input. The new version of the charger has all the same advanced features as the original, like individual cell balancing for up to 6 lithium cells, delta-peak sensitivity, and cyclic charging and discharging. In addition, version two of the charger is more accurate, more stable, and has many new features. Some of the new features include a Micro-USB connection for interfacing with SkyRC’s ChargeMaster PC software and upgrading the firmware, user control over the final battery voltage when charging, individual lithium cell voltage display, and an internal resistance meter.

Bottom view of the iMAX B6AC V2 showing the holographic label with scratch-and-reveal security code.

There are many counterfeit chargers that look almost identical to SkyRC products, so as with the first version, we buy these directly from SkyRC and take care to ensure that our units are genuine. If you would like to double check the authenticity of the iMAX B6AC V2 that you receive, you can reveal the security code under the scratch-and-reveal portion of the holographic label on the bottom of the charger and enter it on the SkyRC web site.

Need batteries for your charger? While we do carry some basic NiMH cells and packs, we recommend that you check out the options at local stores and online, since government restrictions, shipping, and storage issues make this a tough area for a small business to compete in. For larger packs and lithium batteries in particular, there are a number of hobby supply stores shipping from Hong Kong or China that provide excellent options.

For more information about the iMAX B6AC V2 and its features, please see its product page.

Sparky the assistive companion robot

Posted by Claire on 31 December 2014

Forum member jr1985 posted about Sparky, a robot that uses a Micro Maestro and custom Visual Basic software running on a laptop. The goal is for sparky to one day become an assistive companion robot that entertains and helps elderly or disabled people. Currently, Sparky is able to avoid obstacles and navigate through rooms while logging movements to map the areas it encounters. And it has some dancing skills:

For all the Sparky videos, take a look at jr1985’s YouTube channel.

Scary shaking tombstone

Posted by Claire on 15 October 2014
Scary shaking tombstone

Before we started our Halloween projects, several of the Pololu engineers took a trip to a local Halloween store to get inspired. At the store there was a wall lined with the polystyrene foam tombstones that are meant to be stuck into your front lawn. They immediately made me think of the graveyard outside the haunted mansion at Disneyland, and I knew that I wanted to make one of them shake and scream. For added effect, I also picked one that had a few skulls on it, so I could place red LEDs in the eyes. Below are some of the details that went into making the project so far. Continued…

New Product: 5V, 5A Step-Down Voltage Regulator D24V50F5

Posted by Claire on 3 October 2014
Tags: new products

Remember the post I wrote two weeks ago about our tiny D24V25F5 voltage regulator and some of the testing that we did on it? Well, we were so happy with how that regulator turned out that we decided to make a higher-power version with a larger inductor and beefier MOSFETs. This new regulator is the D24V50F5, and while it is only 0.1″ bigger than its 2.5 A cousin, it can deliver 5 amps!

Side-by-side comparison of the 2.5A D24V25Fx (left) and 5A D24V50Fx (right) step-down voltage regulators.

You can see the bigger MOSFETs on the bottom side:

Comparison of the D24V25Fx (left) and D24V50Fx voltage regulators showing larger MOSFETs on the higher-power board.

The D24V50F5 can also take inputs up to 38V and has typical efficiencies of 85% to 95%. It’s amazing how much power these little 3×3 mm MOSFETs can handle, and with its compact size and high power, this regulator is our new favorite.

New product: 5V, 2.5A Step-Down Voltage Regulator D24V25F5

Posted by Claire on 18 September 2014
Tags: new products

Just about every integrated switching regulator datasheet I come across advertises how easy it is to use the chip, which is probably a good sign that it’s not necessarily that easy. I have designed several of our regulator boards, and for the most part, following the manufacturer recommendations and warnings about short traces and small loops led to working designs without much drama. But, as we push for higher performance, it can get tricky, and I thought I would share some fun pictures of what goes into troubleshooting a design that ought to work but did not.

This instance is about the D24V25F5 step-down regulator we just released today. It should have been straightforward because the basic circuit is very similar to that of the higher-power D24V60F5 and D24V90F5 regulators we released earlier this year. Because this board was supposed to be really small, I designed it with components tightly packed on both sides, which meant I had to make compromises on some of those trace lengths and loop sizes. It wasn’t even clear that the circuit would be routable with just two PCB layers, so when I did find a solution, the design team wanted to try it even though we knew we were pushing our luck.

Pololu 2.5A Step-Down Voltage Regulator D24V25Fx, side view.

Well, if we had been lucky, you might have been reading a less interesting version of this new product announcement three weeks ago. As is typical for these borderline cases, it was the especially hope-dashing kind of failure where a casual test indicated that the board was working, but more in-depth tests revealed stability and performance issues. To make sure the components were not the source of the problem, we put the exact same components onto the PCB of the larger version that already worked. The pictures below show the D24V60F5 regulator (left) populated with its standard components and the D24V60F5 regulator’s PCB populated with the components for the new D24V25F5 (right).

Pololu 5V, 6A Step-Down Voltage Regulator D24V60F5.

Prototype D24V60F5 regulator PCB populated with the components for the D24V25F5 regulator.

The new components on the old board worked, so after some final checks that the new prototypes were assembled correctly, we knew it was a layout issue. We wanted assurance that the design could work before just diving into a four-layer revision, so I took some prototypes and added redundant connections to see their impact. The pictures below show some of my test boards with varying numbers of additional ground connections.

I was able to see that the more additional ground connections there were, the more the issues went away. So, I routed the four-layer board, and after a week of tests on over a dozen prototypes, I am happy to announce the release of our most sophisticated regulator yet! The D24V25F5 buck regulator generates 5 V from input voltages of up to 38 V with typical efficiencies of 85% to 95%. The board measures only 0.7″ × 0.7″, but it allows a typical continuous output current of up to 2.5 A.

We are quite happy with how manufacturing of these units is going, so we expect to be moving toward more dense designs like this in future products.

New products: Perma-Proto breadboard PCBs from Adafruit

Posted by Claire on 28 July 2014
Tags: new products

Securely connecting and mounting the electronics for your robot or other project is a key step in taking it from a prototype to a finished design. These perma-proto boards from Adafruit use the same basic through-hole layout as standard solderless breadboards while allowing for permanent solder connections, which makes it easy to transfer your electronics from one to the other.

We are now carrying four types of perma-proto boards:

The quarter-size perma-proto board, at 1.7″ × 2.0″, is slightly larger than a 170-point breadboard and has labels, 15 rows of pins, and two mounting holes.

Adafruit Perma-Proto Quarter-Sized Breadboard PCB.

Adafruit Perma-Proto Half-Sized Breadboard PCB.

The half-size perma-proto board is 3.2″ × 2.0″, which is about the same size as our 400-point beardboard, and has labels, 30 rows of pins, and two mounting holes.

The full-size perma-proto board is similar in size to our 830-point breadboard. It measures 6.2″ × 2.0″ and has labels, 60 rows of pins, and three mounting holes.

Adafruit Perma-Proto Full-Sized Breadboard PCB.

Adafruit Flex Perma-Proto Half-Sized Breadboard Flex-PCB.

The flexible perma-proto board is made of a thin polyamide film that allows it to be bent, flexed, and cut to fit your project. This version is 3.1″ × 1.7″ (similar in size to the half-size board) and only 0.005″ thick. It contains 30 rows of pins and three mounting holes.

Each board uses 47 mil (1.2 mm) diameter through holes to accommodate parts with thick leads and is through-plated for strength, which means that the pads are less likely to be ripped of during soldering or rework.

Geiger counter using A-Star

Posted by Claire on 25 June 2014

The inside of the Geiger counter.

The home-made Geiger counter featured in this post by forum user bob_day uses an A-Star 32U4 Micro, LND 7313 Geiger tube, and LCD to measure and display Geiger tube counts. The LCD displays the counts detected during the last minute, the average counts per minute, and the maximum counts in a minute. The project was originally designed for the Arduino Micro, but the program was able to run on the A-Star without any software modifications. The entire project is powered from one S7V8A adjustable step-up/step-down voltage regulator, and the conditioning part of the circuit, which shapes the output into narrow pulses, was designed by bob_day . Schematics and code for the project are included in the forum post.

The case and display of the Geiger counter.

New Products

Wall Power Adapter: 5.25VDC, 2.4A, 20AWG MicroUSB Cable
Aluminum Standoff for Raspberry Pi: 11mm Length, 4mm M2.5 Thread, M-F (4-Pack)
Addressable RGB 60-LED Strip, 5V, 2m (SK9822)
Addressable RGB 8x32-LED Flexible Panel, 5V, 10mm Grid (SK9822)
Verbal Machines VM-CLAP1 Hand Clap Sensor
Addressable RGB 30-LED Strip, 5V, 1m (SK9822)
RoboClaw 2x60A Motor Controller (V6)
Addressable RGB 60-LED Strip, 5V, 1m (SK9822)
Pololu 5V Step-Up/Step-Down Voltage Regulator S9V11F5
Wall Power Adapter: 12VDC, 1A, 5.5×2.1mm Barrel Jack, Center-Positive
Log In
Pololu Robotics & Electronics
Shopping cart
(702) 262-6648
Same-day shipping, worldwide
Shop Blog Forum Support
My account Comments or questions? About Pololu Contact Ordering information Distributors