I’ve been a member of Hackspace for quite some time, though I have very little hands on experience with electronics or making things or anything like that, and have up until now tended to only use the Hackspace occasionally for somewhere to work from. When the Arduino workshop was announced I thought it sounded not only very good value for money at £80 for a two day instructor-led course, but also would be a great way to broaden my skills.
In the interest of full disclosure, as a minor fanboy of the Hackspace I am prone to want to portray it and all its endeavours in a good light. However I am trying to write this from the point of view of a paying customer of the workshop (which I was), and will try to be fair and objective.
What we got
Included in the £80 (£100 for non-members) workshop fee was an Earthshine Electronics Arduino compatible starter kit worth about £40, containing a DFRduino Duemilanove and over 150 components for use in the various tutorials.
I arrived early on the first day expecting to touch in with my Oyster card (Hackspace’s members can access the space 24/7 using any compatible RFID card), but the door was already open and the place was a hive of activity. Inside I found Andy “Bob” Brockhurst, Charles, Neil, Mike from Earthshine, Adrian and several others busy tidying the place up making it usable for a workshop. This included attaching a shelf to one wall for the projector to sit on!
Eventually the projector was sorted out, a rather makeshift but legible screen put up for it and things began with a presentation from Bob. Bob’s presentation explained what an Arduino is, the sorts of things they might be used for, the concepts behind “open source hardware”, the available software and some resources for getting more information and hardware. Bob’s presentation is available on his github.
Once the presentation was concluded, Bob, Mike, Adrian et al went around ensuring we all had the Arduino IDE installed. This is a piece of Java software comprising a basic editor for the C-like language Arduino is programmed with, together with facilities to compile and upload the code to the board, and a few other features.
There was also a brief diversion into Fritzing, which is another piece of open source software used for producing layouts and prototypes of circuits for sharing with others, ease of manufacturing, etc. Fritzing is not necessary to use the Arduino, but was used to display the board layouts for the examples.
Amongst the delegates there was a mix of Windows, Mac and Linux laptops but we were all eventually able to download and install the IDE. The supplied USB cable once connected to an Arduino board appears as a serial port on the computer, and the IDE just has to be told which board model you have and which serial port to use.
I had a bit of a false start with installing the IDE on Linux, owing to me not reading the documentation. It is necessary on Ubuntu to already have installed
avr-libc otherwise the IDE will be unable to compile your sketch to object code. I think I was in the minority using Linux; it seems Windows is preferred amongst AVR coders. The usual Java blah is needed to run the IDE, but I already had that.
I’m not sure who prepared the refreshments; I know that Clare, Charles’s other half had some hand in it but I don’t know if she was solely responsible. In any case, tea, coffee, cordial, biscuits and flapjacks were provided throughout both days, with sandwiches (two different cheeses, tuna, egg, bacon), crisps and fruit for lunch.
Walk-through of examples
Once everyone had their IDE up and running and had confirmed that the IDE could talk to their Arduino, Bob went through some simple example circuits. While Bob put the circuits up on the projector and explained how they worked, both electronically and software-wise, Mike, Neil and other knowledgeable Arduino hackers moved around the room helping people out where necessary.
Bob’s examples built on each other progressively, and included:
- Making an LED blink
- Simulating a traffic light sequence with 3 LEDs
- Adding a button to simulate a pedestrian crossing feature
- Adding a buzzer which sounds when safe to cross
There was also a final example which used a motor as a spinner to simulate an accessible pedestrian crossing, but most people did not attempt this due to the risks of damaging the Arduino board.
Sample code and Fritzing files available on Bob’s github.
The last few hours of the day were taken at our own individual speeds, practising with the examples and seeing what we could get working. Some people surged ahead, completing all examples and then moving on to their own ideas, whereas others took longer or needed some assistance. As far as I could see everyone made their way through the first four examples.
One person’s Arduino was damaged towards the end of day one and was replaced by Mike.
Wrap up of day one
Some time between 4 and 5pm most people started to pack up and we were reminded to try to think of a personal project to work on the next day if we had not done so already.
I arrived just before 10am the next day owing to general Sunday public transport fail, Jubilee line closure etc., again expecting to swipe my Oyster and again being confounded. This time however it was by a group of people standing outside the Hackspace.
It transpired that we had perhaps tried to be too clever for our own good and the door computer had crashed some time in the night, preventing all of us from getting in. After about 30 minutes, some IRCing, unsuccessful nmapping and leaving of voicemails, Mark popped up on IRC and kindly rushed over to let us in with a real metal key.
For the rest of this day we all worked on our own individual ideas, with Bob, Neil, Adrian and others milling around dispensing masses of assistance.
I couldn’t really think of anything practically useful to work on so decided I just wanted to push the limits of what I’d already learned. I’d spied the 8×8 matrix display in the kit box and wanted to play with that, but this first would involve learning how to drive a shift register.
The 8×8 matrix has 64 LEDs (actually 128 since each one is either red or green), and connecting up 64 outputs would not only be extremely tedious, the Arduino doesn’t have that many outputs anyway. The component actually has only 16 pins but even so, 16 outputs is too many. A shift register helps solve this by allowing the control of 8 outputs using only 3 pins.
The basic idea is that you use one pin to tell the shift register when you’re ready to start or finish feeding it data, one pin to tell it there is a new piece of data to read, and a third pin for the data itself. After you’ve indicated that you’re finished, all the data you’ve fed in will be output. The 74HC595 shift registers in the kit box have 8 outputs each.
In order to get a working knowledge of the shift register I decided to first try using one to drive 8 LEDs, first to make them count in binary and then to display various patterns. After that I would go on to try the shift registers with the matrix display.
I put a circuit together by following the commentary in one of the examples in Earthshine’s Complete Beginners Guide to the Arduino. Unfortunately I couldn’t get it to produce sensible results. At times it seemed like I almost had it, with it counting up in binary correctly except for a couple of values. Other times it was just completely messed up with the LEDs cycling through all kinds of patterns.
I found debugging this to be very difficult.
Dammit Jim, I’m a sysadmin, not a hardware hacker; when I write awful sysadmin Perl I at least have some idea how to debug it! After a couple of hours of frustration I had to ask Bob for help, and after a good while of him checking everything I’d done several times, he was stumped too.
Neil then wandered over and measured the frequencies the Arduino was producing, confirming that my code and the Arduino were working correctly, narrowing the breakage down to my circuit. He got his magnifying glass out, we got the datasheet for the shift register, and after a short while he noticed that I was trying to use the shift register’s latch pin as a clock and vice versa.
It turned out that while the pinout of the shift register was correct in the Earthshine guide, the commentary in the guide had switched around the purpose of the shift register clock input pin and the storage register clock input pin, which accounted for the bizarre behaviour I was seeing. It worked! A similar example on the Arduino site has things the correct way around.
I went ahead and wrote the code to do binary counting and then to put some simple patterns on the LEDs, but after all that I felt a bit too burnt out to go on to the matrix display and decided to quit while I was ahead. I definitely feel confident enough to tackle this on my own now though.
I think two more people’s Arduinos were damaged on the second day.
This workshop was indeed incredible value for money. I think the components, presentation and walk through of examples alone were easily worth £80 and could have been done in one day. What was worth so much more was having knowledgeable people in the same room as you for two days, personally guiding you through the examples and discussing your own ideas. I’ve paid 5 times as much for one day courses that were nowhere near as good.
This could and probably should have justified a doubling or more of price, but I can understand that this was the first workshop put on in the Hackspace and there was a desire to sell it out and gain some experience from the host side.
I hope the workshop is repeated. If it is, and you’re interested in this sort of thing, you should book it quickly.
Suggestions for improvement
Many Bothans diedTwo or three Arduinos died during the course of the workshop. As far as I could tell through overhearing conversation, every case was related to running them from the power supply instead of the USB power. I think someone put a multimeter on one and found it was supplying over voltage. I understand better PSUs will be sought in future.
- We struggled to fit everyone in. The last two late-comers had less than ideal seating during the presentation because Bob needed to stand in one of the seating places in order to do the presentation. This could probably be easily remedied by tidying up the Hackspace a bit before the day of the workshop. I don’t think there’s any need to reduce the number of participants.
- The screen for the projector was rather tatty and ramshackle. It didn’t matter much for Bob’s presentation because his slides were very simple and just about fitted on the screen, but anything more demanding than that would have real problems.
- The door episode was extremely unfortunate timing. A suggestion was made that at least two of the people running any workshop should have keys in case of similar emergencies. Sounds reasonable.
It looks like the Hackspace are conducting a debrief and some of these issues have already been raised, so it should be easy to improve for next time.