Tag Archive | "desire"

Kit Review – adafruit industries mintyboost v3

Hello readers

Today we are going introduce another useful kit from adafruit industries – their mintyboost kit. The purpose of this kit is to provide a powered USB socket suitable for charging a variety of devices, powered from a pair of AA cells. The mintyboost is quite a simple, yet clever design – the latest version is based around the Linear Technology LT1302 DC/DC step-up converter that we examined a few months ago – and can provide a full 5 volts DC at 500 milliamps, enough to charge the latest round of USB-chargable gadgets, including those iPhones that I keep hearing about. And unlike an iPhone, the mintyboost kit is licensed under a Creative Commons v2.5 attribution license.

But enough reading, time to make it. As always, instructions are provided online – are easy to follow and very clear. The kit will arrive in a nice reusable anti-static bag:


Which contains everything you need except for AA cells and a housing:


Where or how you contain your mintyboost is a subjective decision, and will probably vary wildly. The original design brief was to have it fit inside a tin that Altoids confectionary is sold in, however those are not available around my area. But I found a suitable replacement. The PCB is very small, and designed to fit snugly inside the aforementioned tin:


Very small – less than 38 x 20 mm in dimension. However with some care and caution, you can solder the components without using a vice or “helping hands”. Though if you have access to these, use them as it will make life a lot easier. Before we move on, please note that my 49.9k ohm resistors, ceramic capacitors and the inductor are a different size to those included with the kit. This is my second mintyboost, and to save money I bought the PCB only and used my own parts to make this one.

If size is an issue for you, it is a good idea to buy the entire kit, as you will have resistors that fit flush with the PCB, unlike mine 🙂


However, construction moved along smoothly, by following the instructions, double-checking my work and not rushing things. There is some clever designing going on here, I have never seen a resistor underneath an IC socket before!


But when PCB real estate is at a premium, you need think outside of the box. After this stage there was just the electrolytic capacitors and battery holder to install. One that has been done, you can insert some fresh AA cells and check the output voltage on the USB lines:


Looking good, however it could have been a bit higher if the AA cells were freshly charged. But the second USB voltage was spot on:


Success! It always feels good to make a kit and have it work the first time. The last soldering was to take care of fitting the USB socket, and then it was finished:


Now to take it for a test run. I have two USB-charging items to test it with, my HTC Desire:


The LED to the right of the htc logo indicates the power is in, and the battery indicator on the left of the clock indicates charging. Excellent. The phone battery is 1400 mAh – I most likely won’t get a full recharge from the two AA cells, but enough to get me through an extra night and half a day. The mintyboost is a perfect backup-charging solution to leave in your backpack or other daily case. And now for something from Apple, an iPod of about four years old (it still holds a charge, so I’m not falling for the “buy a new iPod every twelve months” mantra):


Again, perfect. Apple equipment can be quite finicky about the voltages being fed to them, and will not work if there is a slight difference to what the device expects to be fed. As you can see the team at adafruit have solved this problem nicely. There is also much discussion about various devices and so on in their support forums.

Now for the decision with regards to housing my mintyboost. The Altoids tins are not an option, and I’m not cannibalising my mathematical instruments storage tin. But I knew I kept this tin for a reason from last February:


Plenty of room for the PCB, the charging cable, emergency snack cash and even more AA cells if necessary. And where else could I have put the socket, but here:


🙂 I have named it the bunnyboost:


… who can safely live in the bottom of my backpack, ready to keep things powered at a moments’ notice. Excellent!

As you can see, the mintyboost is a simple, yet very practical kit. It would also make a great gift for someone as well, as USB-charging devices are becoming much more popular these days. If you are looking to buy a kit, those of you in the Australasian market can get one from Little Bird Electronics, or globally available from adafruit industries. High resolution photos are available on flickr.

Once again, thank you for reading and I look forward to your comments and so on. Please subscribe using one of the methods at the top-right of this web page to receive updates on new posts, and if you have any questions – why not join our Google Group? It’s free and we’re all there to learn and help each other.

[Note – this kit was purchased by myself personally and reviewed without notifying the manufacturer or retailer]

Posted in adafruit, kit review, LT1302, mintyboostComments (6)

Moving Forward with Arduino – Chapter 16 – Ethernet

Use Ethernet with Arduino in chapter sixteen of “Getting Started with Arduino!” by John Boxall – A tutorial on the Arduino universe. The first chapter is here, the complete series is detailed here.

[Updated 09/01/2013]

In this instalment we will introduce and examine the use of Ethernet networking with Arduino systems. This tutorial covers receiving data from an Arduino over the Internet. If you are interested in controlling an Arduino over the Internet, see here. It will be assumed that you have a basic understanding of computer networking, such as the knowledge of how to connect computers to a hub/router with RJ45 cables, what an IP and MAC address is, and so on. Furthermore, here is a good quick rundown about Ethernet.

First of all, you will need an Ethernet shield. There are a few on the market, such as the original version by the Arduino team. Readers of my articles will know my preference is for the Australian-designed Freetronics line of hardware, so I will be using their EtherTen – which combines an Arduino Uno-compatible board with an Ethernet shield. Plus it also has some interesting power-over-Ethernet features which you can read about here. However as long as your Arduino Ethernet shield has the W5100 controller IC – you’re fine.

Now, let’s get started!

This is an ethernet shield on top of an Arduino-compatible board. Nothing new here – just a nice RJ45 socket which you connect to your router/hub/modem with a patch lead:


First of all, let’s do something quick and easy to check that all is functional. Open the Arduino IDE and select File > Examples > Ethernet > Webserver. This loads a simple sketch which will display data gathered from the analogue inputs on a web browser. However don’t upload it yet, it needs a slight modification.

You need to specify the IP address of the ethernet shield – which is done inside the sketch. This is simple, go to the line:

And alter it to match your own setup. For example, in my home the router’s IP address is, the printer is and all PCs are below …50. So I will set my shield IP to by altering the line to:

You also have the opportunity to change your MAC address. Each piece of networking equipment has a unique serial number to identify itself over a network, and this is normall hard-programmed into the equipments’ firmware. However with Arduino we can define the MAC address ourselves. If you are running more than one ethernet shield on your network, ensure they have different MAC addresses by altering the hexadecimal values in the line:

However if you only have one shield just leave it be. There may be the very, very, statistically rare chance of having a MAC address the same as your existing hardware, so that would be another time to change it. Once you have made your alterations, save and upload the sketch to your Arduino or compatible board. If you haven’t already, disconnect the power and add your Ethernet shield.

Now, connect the shield to your router or hub with an RJ45 cable, and the Arduino board to the power via USB or external power supply. Then return to your computer, and using your web browser, enter your Ethernet shield’s IP address into the URL bar. The web browser will query the Ethernet shield, which will return the values from the analogue ports on the Arduino board, as such:

As there isn’t anything plugged into the analog inputs, their value will change constantly. Neat – your Arduino is now serving data over a network. It is quite motivating to see it actually work.

At this point – please note that the Ethernet shields use digital pins 10~13, so you can’t use those for anything else. Some Arduino Ethernet shields may also have a microSD card socket, which also uses another digital pin – so check with the documentation to find out which one. If you are considering using an Arduino Mega and Ethernet – check out the EtherMega.

Nevertheless, now that we can see the Ethernet shield is working we can move on to something more useful. Let’s dissect the previous example in a simple way, and see how we can distribute and display more interesting data over the network. For reference, all of the Ethernet-related functions are handled by the Ethernet Arduino library. If you examine the previous sketch we just used, the section that will be of interest is:

Hopefully this section of the sketch should be familiar – remember how we have used serial.print(); in the past when sending data to the serial monitor box? Well now we can do the same thing, but sending data from our Ethernet shield back to a web browser – on other words, a very basic type of web page. However there is something you may or may not want to  learn in order to format the output in a readable format – HTML code. I am not a website developer (!) so will not delve into HTML too much.

However if you wish to serve up nicely formatted web pages with your Arduino and so on, here would be a good start. In the interests of simplicity, the following two functions will be the most useful:

Client.print (); allows us to send text or data back to the web page. It works in the same way as serial.print(), so nothing new there. You can also specify the data type in the same way as with serial.print(). Naturally you can also use it to send data back as well. The other useful line is:

this sends the HTML code back to the web browser telling it to start a new line. The part that actually causes the carriage return/new line is the <br /> which is an HTML code (or “tag”) for a new line. So if you are creating more elaborate web page displays, you can just insert other HTML tags in the client.print(); statement.

Note that the sketch will only send the data when it has been requested, i.e. received a request from the web browser. So let’s put our new knowledge into action with some simple sensor hardware – measuring temperature and pseudo-light levels. In chapter fourteen we did this and sent the results over the air using XBee wireless modules. Now we shall make that data available to a web browser instead.

We will need:

  • Arduino Uno or compatible board and Ethernet shield, or
  • Freetronics EtherTen
  • Analog Devices TMP36 temperature sensor
  • 10 k ohm resistor
  • light-dependent resistor/photocell

Here is the schematic for the circuit:


and in real life. If you were to construct a permanent application, the Freetronics shield is great as you have all that prototyping space:


and download the sketch from here. Finally, the example in action, on the desktop PC:


… and on a phone via my internal wireless access point (the screen is a little fuzzy due to the adhesive screen protector):


Now you can see how easy it is to send data from your Arduino via an Ethernet network to a web browser. But that is only to a local web browser. What if I wanted to read that data using my phone from an Internet cafe in downtown Vientiane? It can be done, but is a little bit tricky for the uninitiated – so let’s get initiated!

You will need a static IP address – that is, the IP address your internet service provider assigns to your connection needs to stay the same. If you don’t have a static IP, as long as you leave your modem/router permanently swiched on your IP shouldn’t change.

However, if your internet service provider cannot offer you a static IP at all, you can still move forward with the project by using an organisation that offers a Dynamic DNS. These organisations offer you your own static IP hostname (e.g. mojo.monkeynuts.com) instead of a number, keep track of your changing IP address and linking it to the new hostname. From what I can gather, your modem needs to support (have an in-built client for…) these DDNS services. As an example, two companies are No-IP and DynDNS.com. Please note that I haven’t used those two***, they are just offered as examples.

Now, to find your IP address, usually this can be found by logging into your router’s administration page. For this example, if I enter in a web browser, and after entering my modem administration password, the following screen is presented:


What you are looking for is your WAN IP address, as artistically circled above. To keep the pranksters away, I have blacked out some of my address. The next thing to do is turn on port-forwarding. This tells the router where to redirect incoming requests from the outside world. When the modem receives such a request, we want to send that request to the port number of our Ethernet shield. Using the Server server(80); function in our sketch has set the port number to 80. Each modem’s configuration screen will look different, but as an example here is one:


So you can see from the line number one, the inbound port numbers have been set to 80, and the IP address of the Ethernet shield has been set to – the same as in the sketch. After saving the settings, we’re all set. The external address of my Ethernet shield will be the WAN:80, e.g.  213.123.456.128:80 into the browser of a web device will contact the lonely Ethernet hardware back home. Furthermore, you may need to alter your modem’s firewall settings, to allow the port 80 to be “open” to incoming requests. Please check your modem documentation for more information on how to do this.

Now from basically any Internet connected device in the free world, I can enter my WAN and port number into the URL field and receive the results. For example, from a phone when it is connected to the Internet via 3.5G mobile data:

How neat is that? The web page, not the phone. Well, the phone is pretty awesome too.

OK, it’s just the temperature – but with your other Arduino knowledge from our tutorials and elsewhere – you can wire up all sorts of sensors, poll them from your Arduino and use the Ethernet shield and an Internet connection to access that data from anywhere. Here are some applications that spring to mind, all can be made possible with details from our previous tutorials:

  • Sensitive temperature monitoring (e.g. a smoke house, tropical fish tank, chemical storage room, and so on);
  • “Have the children come home from school?” – children must swipe their RFID tag when they arrive home. Arduino stores time and tag number, which can be converted into display data for web output;
  • For single room-mates – perhaps a remote, high-tech version of a necktie on a doorknob… when the “busy” flatmate arrives home, they turn a switch which is read by the Arduino, and is then polled by the sketch – the other flatmates can poll from their phone before coming home;
  • Using reed switch/magnet pairs, you could monitor whether important doors or windows (etc.) were open or closed.
  • A small RFID could be placed on the collar of your pet – two RFID readers on each side of a cat/dog flap door. Using simple logic the Arduino could calculate if the pet was inside or outside, and the last time the pet went through the door.
  • send twitter messages

The possibilities are only limited by your imagination or requirements.


Have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column, or join our Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

Posted in arduino, DEV-09026, education, ethernet, etherten, learning electronics, lesson, microcontrollers, shield, tronixstuff, tutorialComments (13)

Subscribe via email

Receive notifications of new posts by email.

The Arduino Book

Arduino Workshop

Für unsere deutschen Freunde

Dla naszych polskich przyjaciół ...

Australian Electronics!

Buy and support Silicon Chip - Australia's only Electronics Magazine.

Use of our content…

%d bloggers like this: