Gareth from 4tronix was kind enough to send me one of these to review and say what I like about it.
Introduction
The 4tronix Agobo is a robotics kit for the Raspberry Pi model A+. It comes as a kit which requires assembling, but not soldering (although you can do some). You can see the contents in the picture below: the main board (with attached motors), 2 wheels, a battery pack and cable, a castor kit and various fixings. The low-powered model A+ is ideal for robotics and this kit takes advantage of its tiny size – the whole thing when assembled is itself very small and it’s just the sort of kit to get children excited about electronics and programming.
The main board itself (shown below in close-up) has attached infra-red line sensors on the underside, the previously mentioned motors, plus headers for serial, I2C and also a header at the front of the board specifically designed for an ultrasonic distance sensor. There are also two (very bright) white LEDs which are controllable in software, plus a “mode” button. All this connectivity on the board is fantastic as it saves you having wires all over the place. There is also a break-out for the entire GPIO. This comes in useful with the optional prototyping plate that you can buy as it plugs directly into that (with some soldering needed). There are some small prototyping areas in the middle of the board with GND, 3v3 and 5V rails. At the rear is the microUSB power port which means you are delivering 5V directly to the board as well as to the Pi. The circuit board is of very high quality and the silk-screening is superb, which means everything is clearly labelled.
Overall, I really must commend Gareth on his design – he’s clearly taken a lot of time and thought over it.
Assembly
I chose to assemble the kit with the optional prototyping board, the PlusPlate. This board fits over the top of the rest of the kit and allows you to wire on additional components. There are some fiddly moments involved in putting it together. The ball castor assembly requires you to hold it together while you screw it to the board. This can result in ball bearings and screws going all over the place and there’s definitely a knack to doing it. I’ve since spoken to Gareth about it and, until they figure out a better way, they are going to glue the assembly together which should make it a lot easier.
The assembly instructions are excellent – perhaps for the more difficult builds (those including the prototyping plate) there could be some extra photographs to help you work out which screw/fixing goes where, but to be honest that’s half the fun and challenge of putting it together. I only swore a few times 🙂
The soldering that I had to do (which is only necessary when dealing with the PlusPlate) was simple enough – two male 40-pin headers and one female 40-pin header is all that’s needed.
Here is the robot all assembled (without the tubular battery pack) so you can see what you end up with. From this picture you can clearly see the Neopixel attached to the prototyping board, which is there for no other reason than added blinkiness, as far as I can tell! The PlusPlate is, again, of very high quality and is clearly labelled with power and ground rails.
The nice thing about using the PlusPlate with the kit is that it means the HDMI port is available for use. This isn’t the case when the PlusPlate isn’t used as the battery holder obscures the port. This could be a little annoying if you’re trying to program the A+ and you want to be able to use a screen as it more or less forces you to use a wireless dongle or serial cable to do so, or do as I did and keep swapping the SD card between the A+ and a B+ that is wired to the screen/keyboard. The build does leave the USB port free so it means you can plug in a wifi dongle or keyboard. I would recommend building it with the PlusPlate – you can just about use the HDMI port and still power up the Agobo (the socket is almost obscured by the HDMI cable I was using).
Software
- The main library (which obfuscates a lot of things to do with turning GPIO pins on and off).
- A motor testing script that takes input from your cursor keys and makes the robot move in that direction.
- A script to test the line sensors.
- A script to test the ultrasonic distance sensor.
- A script to flash the white LEDs on the main Agobo board.
- A script to test out the Neopixel on the PlusPlate. (In order to use this script, you’ll need to install a Python library which is available on Adafruit’s website).
Here’s a video of all the scripts being tried out:
I found all the software to be of the highest quality, with plenty of comments to help you get your head around what the code is doing. You shouldn’t have any problem, with a little time, putting it all together into a fully-featured program. Gareth is going to do some more tutorials on things like getting your program to run on boot-up so keep an eye out for those.
Pricing
The best thing I can suggest for pricing is to head on over to 4tronix’s store and take a look. The base model is £24.95 plus VAT and delivery. There are lots of options, though, including buying a Raspberry Pi model A+ in the bundle. If you went for the whole package, including the A+, the acrylic plate cover, the PlusPlate, the console/debug cable, a wifi dongle, an SD card and an ultrasonic sensor, it comes to £75.84 including VAT and delivery. I would strongly recommend going for a package with the PlusPlate as it gives you that much more flexibility and hackability.
Conclusion
The Agobo is simply a terrific product and it’s got a great price attached. The base model is just under £30 including VAT, and you really can’t go wrong with the quality on offer. Assembly is fun, if a little fiddly (but then where’s the fun in making it really easy?) and the enclosed software is top-notch.
So, who would I recommend it for? Well, to be honest it’s an ideal platform for anyone due to the flexibility of the kit, especially if you build it with the PlusPlate. I can imagine it being really popular with schools, due to the low price tag and small size. It’s also an ideal kit for parents to build with their kids. There’s a bit of physical work to do, which is the start of the learning process, plus you get a lot of help with writing the software. The inbuilt line sensors and space for the ultrasonic means that it’s perfect for autonomous use as well as remote-controlled operation.
Really, really well done 4tronix. Highly recommended.
