ATmega328 development kit

16.10.2011 13:44

Protostack recently sent me their new ATmega328 development kit complete with a USBasp programmer to test and review. A week ago it arrived in perfect condition from Australia, nicely wrapped in antistatic bags and a padded envelope. I've soldered it together and played around with it a bit and have some first impressions to share.

ATmega328 development kit in an antistatic bag

The development kit is in essence a dual-layer PCB with some basic circuitry for supporting a through-hole ATmega328 microcontroller, surrounded with a large prototyping pattern.

Obviously versatility in all respects was a priority. The board has space for either an on-board TO-220 regulator (with two possible pinouts covering the popular options like 7805 and 1117) or a CR2032 battery holder. The 34 page User's Guide contains descriptions of several power supply configurations for either external or internal power.

Ease of connectivity to the microcontroller has been equally well taken care of. Ports are nicely placed in alphabetical order on both sides of the chip so you don't have to memorize the pin-out. There's an an option of either a 6 or 10 pin ISP connector to fit any programmer you might already have. The prototyping area has the layout known from solder-less protoboards: ground and power rails horizontal and signal lines vertical. It can easily accommodate a few DIP integrated circuits and passive elements. Nice addition is also a special place where you can solder an 18-pin flat cable (IDC) connector which is usually a pain on such layouts.

The board is designed so that many can be stacked on top of each other (you can also get stackable PCBs that only contain the protoboard pattern without the CPU). That's why you also get patterns on the edges that can accommodate stacking headers for routing signals between boards.

Assembled Protostack ATmega328 development kit

Assembling it was trivial. Between the step-by-step instructions in the manual and the silk screen showing passive component values it's hard to get anything wrong. The kit includes the CPU on a socket, 10 pin ISP connector for the USBasp programmer and components for an on-board regulated power supply (battery clip isn't included), 20 MHz quartz oscillator and a LC filter for the ATmega's ADC power.

During assembly my only wish would be for thermals around pins on ground planes, which would make soldering them a bit easier. I would also put the 100 nF ceramic blocking capacitor as close as possible to the CPU instead of the other side of a power strip that crosses the board and back. Granted such a board isn't usually used for noise sensitive designs, but it's good practice nonetheless.

Programmer is a GPL design by Thomas Fischl and works with any non-ancient version of avrdude. ATmega328 is famous because of Arduino anyway, so using it with the free avr-gcc stack shouldn't be a problem.

The only snag I hit when I was uploading the first Hello, World! program was that the chip I got with the development board was ATMEGA328-PU, while avrdude only knows so far about the ATMEGA328P-PU. The chips are identical in all respects except that the P version (for picopower) consumes less current. This means that you either have to use the ATMEGA328P profile and force chip signature check with -F flag or patch avrdude with this patch I wrote.

So, to wrap this up. This looks like a nice board for developing a prototype or for one-off projects where you don't want to roll your own PCB. It's not a fully-tricked out affair with included buttons and display, but if you like simplicity it's hard to get more basic than this. At $20.80 it's three-quarters of the cost of an Arduino Uno and gives you the same CPU with more convenient prototyping (if you're used to soldering that is) but omits the integrated USB. It allows you to use a stack of free as in freedom tools to develop and would be a nice start for an open hardware project. Last but not least, Protostack has flat rate worldwide shipping, which is always a nice touch for us in the everywhere else zone.

Posted by Tomaž | Categories: Digital

Comments

A concrete, clear review -- thanks!

Posted by John M

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