Kit review – Freeduino v1.22 Arduino-compatible

Hello readers

Time again for another kit review. Today we will examine the Freeduino Arduino Duemilanove-compatible board in a kit. It is always interesting to see how the different types and makes of Arduino-compatible boards present themselves, so this is review is an extension of that curiosity. This kit was originally designed by NKC Electronics and released under a Creative Commons license.

The packaging can either be classed as underwhelming or environmentally-friendly, as the kit arrives in several plastic resealable bags. Upon emptying them out we are presented with the following, the parts:

and the PCB:

Hopefully you noticed what ends up being the key features of this kit – the pre-soldered FTDI IC and mini-USB socket. This means the Freeduino can be used with a USB cable (not included) and not an expensive FTDI cable. The PCB itself is very solid, has a very descriptive silk-screen layer with all the component positions labelled, is solder-masked, and has nice rounded corners.

Reviewing the included parts did make me wonder why the supplier has used 5% carbon-film resistors and ceramic capacitors instead of polyesters (except for one). It turns out that Seeedstudio (the distributor for my example kit) claim 5% resistors are easier to read. Originally I claimed that this was an excuse to save a few cents, however a few people have said that such resistors are easier to read.

Furthermore, this one missed out on the polyfuse for USB overcurrent and short-circuit protection. And whether or not the larger tolerances affect the operation of the board, the cheaper components make the finished product look very 1977. However on a brighter note, an IC socket is included.

Assembly was quick and simple. There are excellent online instructions published by the Freeduino creator NKC available here. However you can also follow the silk-screen labels on the PCB as well. A good method is to start with the lowest-profile compontents, such as resistors and capacitors:

… then followed by the capacitors, crystal, LEDs and reset button:

Notice how the ceramic capacitors lead-spacing is too narrow for the holes on the PCB – this makes me think that the distributor has skimped out on the final product and been too lazy to update the PCB layout. The ATmega168 label is an example of this. Moving forward, the voltage regulator and sockets. The easiest way to solder in the shield sockets is to place them into the pins of an Arduino shield and solder – as such:

And there you have it, one Freediono v1.22 Arduino Duemilanove-compatible board:

The image above also displays another bugbear with this kit – the LED placement. When you have a shield inserted, all of the LEDs are covered up. Furthermore, unlike other Arduino board kits (such as the Freetronics KitTen) you are stuck with the maximum current output of 50mA for the 3.3V rail as there isn’t a dedicated 3.3V voltage regulator on board. Finally, the power switching between USB and the DC socket is controlled with a jumper and header pins between the USB socket and the 7805 voltage regulator.

Although I might have sounded a little harsh about this kit, it is relatively inexpensive, easy to assemble, and has the USB interface onboard. These are all good things. However the PCB layout could have been improved by correctly spacing the holes for the ceramic capacitors, and moving the LEDs to the end of the board so they are visible with shields inserted. What’s the point of having all those LEDs if you cannot see them…

So if you really get the urge to make your own board with the USB interface, or want to give someone some reasonable soldering practice, this isn’t a bad choice at all. Otherwise get a KitTen or save time and buy an Eleven.

As always, thank you for reading and I look forward to your comments and so on. Furthermore, don’t be shy in pointing out errors or places that could use improvement. Please subscribe using one of the methods at the top-right of this web page to receive updates on new posts, follow me on twitter or facebook, or join our Google Group for further discussion.

High resolution images are available on flickr.

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

Otherwise, have fun, be good to each other – and make something!

Kit Review – MDC Bare-bones Board Kit (Arduino-compatible)

Hello readers

Today we continue to examine Arduino-compatible products by assembling an interesting kit from Modern Device Company – their “Bare Bones Board” (to be referred to as BBB). The BBB kit is an inexpensive way to take advantage of the Arduino Duemilanove-compatible platform, and also fills some gaps in the marketplace. Unlike the usual Arduino and compatible boards, the BBB does not maintain the recognisable form factor – that is, you cannot use the variety of Arduino shields. However, the BBB does have all the input and output connections, just in different positions.

So why would you use this kit? If you are looking to create a more permanent Arduino-based project that did not require a shield, and you are in a hurry – the BBB could be easily integrated into your design. Money is saved by not having the usual USB connection, so uploading your sketch is achieved using a 5V FTDI cable or using another Arduino board as the programmer. Furthermore, the PCB is designed in a way that allows you to plug the BBB into the side of a solderless breadboard, which allows prototyping more complex Arduino-based circuits very easy. But more about that later. For now, let’s have a look at construction. An excellent set of instructions and a guide to use is available for download here.

In the spirit of saving money, the kit arrives in a plastic bag of sorts:

And upon emptying the contents, the following parts are introduced:

Regular readers would know that the inclusion of an IC socket makes me very happy. The PCB is thicker than average and has a great silk-screen which makes following instructions almost unnecessary. One of the benefits of this kit is the ability to connect as little or as many I/O or programming pins as required. And for the pins A0~A5, 5V, GND and AREF you are provided with header pins and a socket, allowing you to choose. Or you could just solder directly into the board. These pins are available on the bottom-left of the PCB. However there was one tiny surprise included with the parts:

This is a 15uH SMD inductor, used to reduce noise on the analog/digital section. According to the instructions, this was originally required with Arduino-style boards that used the ATmega168 microcontroller – however the BBB now includes the current ATmega328 which does not require the inductor. However, it is good to get some SMD practice, so I soldered it in first:

Well it works, so that was a success. Soldering the rest of the main components was quite simple, thanks to the markings on the PCB. The key is to start with the lowest-profile (height) components (such as that pesky inductor) and work your way up to the largest. For example:

As you can see from the PCB close-up above, you can have control over many attributes of your board. Please note that the revision-E kit does include the ATmega328 microcontroller, not the older ’168. For more permanent installations, you can solder directly into I/O pins, the power supply and so on. Speaking of power, the included power regulator IC for use with the DC input has quite a low current rating – 250 mA (below left). For my use, this board will see duty in a breadboard, and also a 5V supply for the rest of the circuit, so more current will be required. Thankfully the PCB has the space and pin spacing for a 7805 5V 1A regulator (below right), so I installed my own 7805 instead:

Finally, to make my Arduino-breadboarding life easier I installed the sockets for the analogue I/O, the DC socket and a row of header pins for the digital I/O. Below is my finished example connected into a breadboard blinking some LEDs:

In this example, the board is being powered from the 5V that comes along the FTDI cable. If doing so yourself, don’t forget that there is a maximum of 500 mA available from a USB port. If you need more current (and have installed the 7805 voltage regulator) make use of the DC socket, and set the PCB power select jumper to EXT. For a better look at the kit in action, here is a short video clip:

As you can see from the various angles shown in the video, there are many points on the PCB to which you can use for power, ground, I/O connection and so on. As illustrated at the beginning of this article, a variety of header pins are included with the kit. And please note that the LED on the board is not wired into D13 as other Arduino-type boards have been… the BBB’s LED is just an “on” indicator. However if you are using this type of kit, you most likely will not need to blink a solitary LED. However some people do use the D13 LED for trouble-shooting, so perhaps you will need it after all. Each to their own!

In conclusion, the BBB is another successful method of prototyping with the Arduino system. The kit was of a good quality, included everything required to get working the first time, and is quite inexpensive if you have a 5V FTDI cable or an Arduino Duemilanove/Uno or compatible board for sketch uploading. It is available in Australia from Little Bird Electronics, or directly from Modern Device in the USA.

Once again, thank you for reading this kit review, 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.

High resolution photos are available on flickr.

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