RAREblog

I'm racing ahead with preparations for this Thursday's Kids Adore Ditch . I've already had one small problem to overcome. Poorly 3pi When I looked closely at my 3pi on Friday I realised that the mounting bracket of one of the motors is broken. I've ordered a replacement but it will not arrive until Wednesday at the earliest. I had two 3Pi  demos in mind, and I'm a bit wary of reprograming on the day, so I decided it was time to get a second robot. HobbyTronics offered the best price, and for an additional charge I asked for delivery on Saturday Morning. The new robot arrived on time and I started to prepare the demo. Great documentation from Pololu It's been a while since I did anything with these robots, so I needed to remind myself about how to program them. I love the documentation on the Pololu web  site: it's simple, clear and correct, and covers Windows, Linux and OS/X users. I have the GNU gc++ avr cross compiler and avrdude installed on ...

At last C3Pi can see , thanks to the wonderful Raspberry Pi camera module. You're squinting, C3Pi His first attempt at photography isn't going to win any prizes for composition, but no doubt he will get better with practice. I need to add a robust holder for the camera, but it should mean that we can take some photos at the Kids Adore Ditch event on Thursday. If we're really lucky we may even have streaming video.

C3pi, a veteran robot of my own design, will be joining the Pololu 3pi and me at Kids Adore Ditch this coming Thursday. C3pi a.k.a. Trackbot Trackbot started out as an Arduino-controlled robot . I added a Raspberry Pi , and he became C3Pi. An additional WiFi dongle on the Pi allows me to control him remotely. C3Pi has made several public appearances over the years, and I hope he'll perform well on Thursday. He has one weakness; his batteries are buried in his tummy, so when they run out he needs major surgery. One day I'll come up with a better solution, but probably not this week!

I'm going along to Kids Adore Ditch next Thursday, and this 3pi robot from Pololu is going with me. Pololu 3Pi The 3pi comes ready-built, it's capable, and it's widely available. Its one drawback is that it's relatively expensive, and you need a programmer if you want to run anything other than the fairly limited demo program. I'll take a couple of less expensive alternatives along as well.

One of the last projects that Quick2Wire worked on before the company ceased trading was a display based on the nxp SAA1064 controller and a 7-segment display. There's still a stock of the Quick2Wire boards over at SK Pang , but Quick2Wire never finished the 7-segment design. I'm thinking of restarting that project and I spent a little time this afternoon looking at what would be involved. It seems that the DIP version of the controller is no longer manufactured, and the only display I could find in my parts box is also no longer made. I don't think either of those issues is insurmountable; there seem to be a lot of the DIP chips for sale on eBay, and I guessed that the display pinout was probably the same as you find in more up-to-date displays from the same manufacturer. I was fairly sure that the display was a common-anode type, which the controller requires; I quickly lashed up a test circuit using a lobstar and checked the connections. lobstar and 7 segment d...

There's a revolution underway in Computer Science education. The Raspberry Pi has generated a huge amount of energy and enthusiasm, but there's also a lot of interesting activity around the Arduino. One great Arduino resource is the Shrimp, a low-cost compatible design aimed at educators and hobbyists with limited budgets. Landing the Shrimp You can find out more on the Shrimping It  blog. It describes ' the Shrimp  – a substitute for the Arduino Uno, which can be constructed for about a tenth of the price of the official board, shown here in stripboard and breadboard versions.' Note the absence of a PCB version! That's deliberate: the idea is that you will lean more, and feel more of a sense of ownership, if you have constructed the shrimp from scratch. That makes sense but I can see two situations where shrimp-catchers might prefer a PCB to work with. Some beginners starting out on their own might feel more confident building a PC...

I've just had a nice surprise. Last November I ordered and received a PCB from ragworm , and I've only just got around to assembling and testing it. lobstar v 0.2 I'm very happy with the board. It was my first PCB design using Fritzing , and in this version I introduced a spurious PCB trace. It's turned out to be easy to fix. (I used the high-tech solution of cutting the relevant track with a craft knife.) The area around the capacitor looks a bit messy because I soldered in a 100pF capacitor instead of a 100nF capacitor and had to remove it - it's not a manufacturing problem. The project is a breadboard-friendly Arduino clone inspired by the low-cost, minimalist shrimp . I need a bunch of them - that's why I needed to install burn boot-loaders - and I have a batch of three boards with a corrected design on its way here from OSH PARK in the US. I will need even more of the boards, though, and this morning I spotted an old email from ragworm which ha...

Background In yesterday's post about the phenoptix AVR ISP I said I'd share the details of how I used it to install a boot-loader on a blank chip. I was preparing the chip for use in an Arduino clone of my own design. Watch this space for details of that project! For now I'll talk you though on the boot-loader instalation. You will need a computer running the Arduino IDE version 1.0.5 an Arduino board - in my case, an Arduino UNO SMD edition a blank chip - the ATMega386p that I mentioned yesterday the phenopix AVR ISP programmer, as described yesterday the special phenoptix ISP sketch from Github (details below) Arduino UNO, AVR ISP and ATMega328p What you need to do The process has four main stages: Set up the hardware. Prepare the Arduino. Burn (install) the boot-loader. Test the chip. Set up the hardware Carefully insert the chip you want to prepare into the appropriate socked of the phenoptix AVR ISP shield. You may need to straighten the...

Yesterday I assembled and tested the phenoptix AVR ISP Shield . Here's what I found out while trying it out. First, a bit of background. I needed to build a batch of low-cost Arduino clones. In the past I've bought basic DIY kits from oomlout which include pre-programmed chips, but this time I wanted to keep the cost as low as possible. That meant I needed to buy chips without a boot-loader (as mentioned in yesterday's post)  and then install the boot-loader myself, using an existing Arduino as an In-System Programmer (ISP). I've done that before using a breadboard, some jumper wires and a handful of extra components.  It's a fiddly process and easy to get wrong. This time I decided to get an ISP shield designed for the purpose. It added a little to the cost, but I though it would save time and money in the future and it was fun building it :) There are lots of Arduino ISP shields on the market, including models from Adafruit and SparkFun . I decided to go wi...

There seems to be a dearth of Atmel AVR™ ATMega328 chips in the UK at the moment. with Farnell and RS Components both awaiting deliveries. I needed ten urgently, and found them at Rapid Electronics . These are unprogrammed chips without a bootloader. If you want to use them in Arduino™ clones you will need to burn in a bootloader yourself. I've been doing just that, using phenoptix' AVRISP board with an Adruino UNO.  I'll blog about that tomorrow.