The Burnduino Kit

The Burnduino Shield is, as the name suggests, an add-on ‘shield’ for the Arduino microcontroller and compatibles. It’s designed to make programming an ATmega328 DIP-package microcontroller easier, and turns the Arduino into a remarkably efficient AVR programmer. Features include:

• 28-pin universal ZIF (zero insertion force) socket, meaning no bent pins and fast chip change
• Supports uploading of 16MHz external crystal and 8MHz internal oscillator Arduino bootloaders onto bare ATmega microcontrollers
• Fully supported within the Arduino IDE software
• Allows uploading of bootloaders and sketches from a single shield
• Mode select jumpers mean no rewiring – ever
• Saves money: buy unprogrammed ATmega328 chips and burn the bootloader yourself

The Burnduino is provided as a kit, which contains the printed circuit board, a high-quality 28-pin locking ZIF socket made by 3M, a 16MHz crystal with two 22pF decoupling capacitors, a 10KOhm pull-up resistor for the reset line, male 2.54mm headers and three 2.54mm jumpers for the mode select pins. All components are through-hole and easy to solder, even for a novice.

The Burnduino’s mode select jumpers allow a single shield to perform two tasks: when in ‘BTLDR’ mode, with the RX and TX jumpers open, the Burnduino works with an Arduino and the Arduino-as-ISP sketch to burn new bootloaders onto blank or pre-used ATmega microcontrollers. Close the RX and TX jumpers and move the mode select jumper to ‘SKETCH’ and the Burnduino allows the Arduino IDE to upload sketches to bootloader-equipped ATmegas.

Bootloader Mode

1. Upload the ‘ArduinoISP’ sketch (File – Examples) from the Arduino IDE to your Arduino or compatible board.
2. Connect the Burnduino shield.
3. Set the lower-left Mode Select jumper to BTLDR, shorting the middle and top pins.
4. Remove the jumpers from the RX and TX pins.
5. Insert your ATmega microcontroller into the ZIF socket
6. Select your chosen board type from the Tools – Board menu in the Arduino IDE.
7. Upload the bootloader using Tools – Burn Bootloader – w/ Arduino as ISP.
8. To program another ATmega, simply replace the chip in the socket and burn the bootloader again.

Sketch Mode

1. Remove the ATmega chip from your Arduino board and put it somewhere safe.
2. Connect the Burnduino shield.
3. Set the lower-left Mode Select jumper to SKETCH, shorting the middle and bottom pins.
4. Short the RX and TX pins with the jumpers provided.
5. Select the bootloader type from the Tools – Board menu in the Arduino IDE.
6. Insert your bootloader-equipped ATmega chip into the ZIF socket.
7. Load your sketch into the Arduino IDE and hit the upload button.
8. To upload the sketch to a new chip, simply replace the chip in the ZIF socket and hit the upload button again.

If you want to take advantage of the ATmega’s internal oscillator, which means your finished design can ditch the 16MHz crystal and decoupling capacitors to save money and space, you’ll need to follow the ‘Minimal Circuit’ instructions from the Arduino to Breadboard article to add a new board definition to the Arduino IDE. If you need to upload bootloaders to ATmega328-PU chips – rather than the more common ATmega328P-PU – follow these instructions.

NOTE: The Burnduino uses the ArduinoISP sketch to upload a bootloader to the chip in the ZIF socket. This sketch, at present, does not support the new Arduino Uno, which uses different USB circuitry. If you want to use the Burnduino as an ISP, you’ll need to have an Arduino Duemilanove or third-party compatible with FTDI circuitry instead.

While working on the Standalone Sleepduino, I had cause to burn a custom bootloader to an ATMega328 chip in order to convince it to use its internal 8MHz oscillator instead of an external 16MHz crystal. With an Arduino Duemilanove, that’s not too difficult: follow the instructions from the Arduino To Breadboard article and you’re away.

It does, however, require a bit of time to set up the various wires; then more time is required moving the wires to upload a sketch to the newly-created Arduino-compatible microcontroller. Not much time, to be fair, but time nevertheless. So, the Arduino Burner was born.

The Arduino Burner is a simple shield based on the wiring from the Arduino To Breadboard article. It features room for a 16MHz crystal and decoupling capacitors, although these can be safely ignored if you’re programming an ATMega using the 8MHz breadboard bootloader. Installing them does, however, mean that you have the choice of flashing either bootloader; leaving the holes unpopulated means that you’ll be limited to the 8MHz version only. There’s also a 10K pullup resistor for the reset line, although again this is a ‘nice to have’ that can be ignored.

Usage is simple: stick a raw ATMega328 into the zero insertion force (ZIF) socket in the middle of the shield, set J1 to ‘BTLDR’ and open the RX and TX jumpers and you can burn a bootloader straight from the Arduino IDE. When your bootloader is installed, you can close the RX and TX jumpers and switch J1 to ‘SKETCH’ to upload a sketch – but remember to remove the Arduino’s own ATMega, or you’ll be uploading the sketch to that instead of your new chip!

The ZIF socket means that the legs of the ATMega328 are protected from damage – a key point if you’re burning large quantities of chips. It does, however, increase the cost of the shield quite significantly: a single 28W DIP socket is around 20p, while the particular low-profile ZIF chosen for this shield is around £8 – although this does drop as you buy quantities.

If you’re only creating one-off standalone projects, the Arduino Burner shield is overkill. If you’re doing large quantities and don’t fancy shelling out for a real AVR, however, it can be a serious time-saver.

I’ll be getting a prototype made up towards the end of the month, so pop back then if you want to see the shield in action.

Here’s a quick comparison between the Standalone Sleepduino and its breadboarded prototype:

As you can see, the Standalone Sleepduino is pretty compact, but still packs all the features of the original Arduino-powered version. In fact, it’s possible to take the (socketed) microcontroller out of the Sleepduino and upload a revised sketch, if you’ve got an ATtiny or similar or a spare Arduino to do the programming.

Just in case you doubt it works:

At some point, I’ll be making a few tweaks to the design and then exporting some Gerbers for mass-production. Once I’ve got a costing for the PCB fabrication and parts – a 10K poteniometer, piezoelectric buzzer, three RGB LEDs, three buttons, nine 270-Ohm resistors and an ATMega-328 with socket – I’ll have a better idea of whether the project is worth pursuing.

I snagged myself an ‘Arduino compatible component kit‘ from the lovely guys at Oomlout, which included all the parts I didn’t really need but wanted on hand just in case alongside the most important part of the kit: the ATMega328 microcontroller itself.

Sticking it in a breadboard, I followed the official instructions on how to burn an Arduino bootloader onto an ATMega328 so that it uses its internal 8MHz oscillator instead of an external crystal as its clock source.

At least, I tried to.

I spent about an hour wrestling with one major problem:

avrdude: Expected signature for ATMEGA328P is 1E 95 0F
Double check chip, or use -F to override this check.

Every single time I tried to program the 8MHz bootloader, avrdude told me to -F off. Eventually, I twigged what was going on: official Arduinos have an ATMega328P-PU chip, which you can see printed on top. In good light. If you squint a bit. My chip?

An ATMega328-PU.

One little letter, so much heartache. While the ATMega328P and ATMega328 microcontrollers are pretty much interchangeable, they have different signatures. The version of avrdude that ships with the Arduino IDE knows about ATMega328Ps, but not about ATMega328s. Hence my problem.

Thankfully, there’s a fix. To load an Arduino bootloader onto an ATMega328, open up avrdude.conf (found in /usr/share/arduino/hardware/tools/ on Linux boxes) and search for the string “0x1e 0×95 0x0F”. That’s the signature of an ATMega328P. Replace it with “0x1e 0×95 0×14″, which is the string of an ATMega328 and save the file. If you’re on Linux, you’ll need to be root to save the file. Restart the Arduino IDE, and you should be able to burn the bootloader without any errors.

When you’re done, remember to replace “0x1e 0×95 0×14″ with “0x1e 0×95 0x0F” again, or you’ll get a bunch of messages telling you that only assembler is supported…

Yes. Yes, it would.

As a result, my order with the fab now includes an original Sleepduino shield along with the new design: the Standalone Sleepduino. Measuring a mere 17.6cm², it’s half the size of the Sleepduino shield. It’s not just a reduced footprint, though: as the name suggests, the Standalone Sleepduino no longer requires an Arduino to operate, shaving about £22 off the cost of the device for those who don’t already have an Arduino or compatible hanging around.

How? By taking the chip at the heart of the Arduino, the ATMega328 microcontroller, and embedding it directly into the middle of the circuit board.

To keep the size down and reduce the number of components required, the design of the Standalone includes a few tweaks over a traditional standalone Arduino creation. First of all, the traditional 16MHz crystal and associated capacitors aren’t there: the Sleepduino doesn’t need an accurate clock to work, so I’m using the 8MHz oscillator built in to the ATMega328 instead. There’s also no sign of a 5V regulator: instead, a USB B socket provides connectivity to a PC USB port or USB-based charger, which already provides a regulated 5V feed.

The Standalone Sleepduino won’t be for everyone: while it’s technically possible to reprogram it in the same way as the newly-renamed Sleepduino Shield, it involves having an existing Arduino or AVR programmer and taking the microcontroller off the board. If you’re looking for something to hack, the Sleepduino Shield will still be the better option; that goes doubly if you’ve already got an Arduino.

For those who just want a combination nightlight – with 334 possible colour combinations and four brightness settings, no less – and white-noise generator, however, the Standalone Sleepduino should prove a winner.

If I get enough interest, I’ll be sending off for a batch of both Standalone Sleepduinos and Sleepduino Shields from a PCB fab in China. I’ll then make them available either as a kit, or pre-assembled if you don’t fancy soldering it up yourself. Once my prototypes arrive, I’ll be doing some demonstration videos too.

Oh, and if you’re wondering how the Standalone Sleepduino looks when it’s not in its lovely compact PCB form, here’s the breadboarded prototype:

Not quite so pretty, huh?

Back-of-the-envelope calculations suggest that it’ll cost me around £13 to produce each Sleepduino Standalone kit, plus a quid or so for a USB A-B cable to go with it.

If you’d like to register interest in snagging yourself a kit or pre-made Sleepduino, drop me a line.

Because I value my sleep more than I value my free time, I spent an afternoon designing and coding an combination white noise generator and nightlight for Alice’s nursery. Thankfully, I had the components I needed lying around: an Arduino with breadboard, three RGB LEDs, three tactile buttons, a piezoelectric buzzer and a potentiometer. Plus a whole mess of wiring.

The buttons control the LEDs: each LED has its own button, which cycles it through seven different colours before turning it off. Press the button again, and it’ll switch on again. The pot controls the volume of the buzzer, which exists to vocalise the output of a pseudorandom bit-shift register to generate a pleasing ‘static’ sound.

Set the LEDs to provide whatever level and colour of nightlight you think your baby – or, indeed, you – would prefer, adjust the volume of the white noise (apparently, it should be around the same volume as being in the same room as someone taking a shower) and cross your fingers that you’re going to enjoy the best night of sleep you’ve ever had.

It’s only the second proper night of using it, but it seems to be working: Alice had the best night’s sleep she’s ever had last night, and she’s been settled for a good couple of hours now without issue.

I’ve designed a printed circuit board version of the Sleepduino which plugs into the top of the Arduino without all the distracting and easily-knocked wiring. I’m making an initial prototype, which will arrive from the fab towards the end of the month. If it works, I’ll be opening the floor for anyone who wants to buy one.

Be aware, however: this is an Open Hardware project. I’m making the source code (most of which is appropriated from other projects anyway), schematics and PCB layout available under a Creative Commons Attribution-NonCommercial-ShareAlike licence, meaning you don’t have to buy one from me. If you’d rather, you can just grab the files and make one yourself. I won’t stop you. Hell, I’m actively encouraging it.

The pre-built shields will be for people who don’t fancy building one themselves, and I’ll probably also make them available with Arduino clones underneath so they’re literally ready to go out of the box.

Hopefully you guys will find them as useful as I’ve found the prototype version.

I need to figure out which of the 15 pins I need to connect to my USB adapter, but so far I’ve found four pinouts for the connector – and all four are different. Here’s my best-guess pinout:

1 – Ground
2 – Sound Out
3 – IRQ
4 – Port 1, Data 4
5 – Port 1, Data 3
6 – Port 1, Data 2
7 – Port 1, Data 1
8 – Port 1, Data 0
9 – Port 1, Data Clock
10 – Latch 2
11 – Latch 1
12 – Latch 0
13 – Port 0, Data 1
14 – Port 0, Clock
15 – +5V

In theory, that should be what I need to match up to my RetroGlove USB adapter:

The only question is – have I picked the right Famicom pinout to trust, or will I blow my PowerGlove? Any suggestions, Famicom experts?

I recently installed a new theme on the site – Magzimus – which I pulled from a site promising free WordPress themes. It’s pretty, it has a neat JavaScript slider, and it was a simple install.  What’s not to like?

Well, the fact that searching for my blog on various search engines now shows an affiliation with popular ‘adult entertainment’ site LiveJasmin, for a start.

It seems that the ‘free’ theme has an interesting business model: a hidden bit of PHP code in the admin.php file that checks to see if traffic is coming from a search engine crawler, and if so adding a hidden span at the bottom of the page containing affiliate links to the aforementioned webcam site – and a variety of keywords that are likely to get me significantly different traffic to normal.

I’ve excised the code, and am now waiting for Google et al to update my listing and remove the spurious keywords.

Next time you snag a WordPress theme from somewhere, do what I failed to do: check the code to see exactly what it’s doing to your site.

Anyone who has ever hacked around in their PC will have been hit with an urge to take their tinkering to the next level and create a custom-built device, but few actually try – believing such things to be far too complicated. At least, until the Arduino appeared on the scene.

Originally developed in Italy in 2005 as a tool for students building interactive design projects, the Arduino is a microcontroller-based prototyping board – but one that pretty much removes the barriers to entry that previous electronic prototyping systems had.

The idea behind the Arduino is simple: to create a system that allows electronic circuits to be created, modified, and tested in minutes – complete with a programmable chip in the centre to take control of everything.

What are you still doing here? Go! GO!