The ATtiny2313 is an ideal mocrocontroller for many projects. With only 20 pins, it is relatively easy to build a PCB for, it is low cost, yet it is relatively powerful.
Some of features are
- Up to 20 MIPS Throughput at 20 MHz or 10 MIPS at 10 MHz for the ATtiny2313V
- 2K of Flash
- 128 Bytes Eprom
- 128 Bytes Ram
- One 8 bit and One 16 bit Timer/Counter with prescaler and compare modules
- Four PWM outputs
- Analog Comparator
- USI Universal Serial Interface
- USART – Full Duplex
- SPI port for in system programming
Even with only 20 pins, breadboarding a microcontroller can be a bit of a pain, by the time you have your micro, a crystal and its caps, a reset button plus an ISP header, there isn’t a lot of room left for the rest your circuit.
This simple project makes life easier, by getting the micro and it’s support components off the breadboard and onto a nice little PCB.
To keep things simple, I have used a single sided PCB, and through hole components. I could have squashed averything together into a tiny package, but I don’t think there is any advantage in that for prototyping and experimenting. Also for simplicity I have brought all the pins to one side rather than the usual DIP format.
The circuit is pretty simple, but is all that is required for most modern microcontrollers. R1 keeps the reset pin at 5V unless it is pulled low by the reset button or the programmer, C3 helps filter the power supply. I am using an ATtiny2313V-10 with an 8 MHz crystal. This same configuration will work with an ATtiny2313 and a crystal up to 20MHz.
I have used Eagle PCB design software from Cadsoft. Their free version, available here is limited in some features, but is more than capable of handling anything most hobyiests will throw at it.
The layoput is pretty simple. I have left plenty of space for routing, and only have to add 2 jumper wires for unrouted tracks. The autorouting feature in eagle is pretty good.
I am using the Toner Transfer Method to etch the board, so for the bottom copper layer the image does not need to be reversed before printing.
For complete instructions on using the Toner Transfer Method see my post here.
After etching the board, I have used the same Method to label the top of the board. In this case the image needed to be printed reversed.
Since the board is single sided, the header pins needed to be pushed through from the top and soldered on the underside. To gain the extra length I have pushed the pins through their plastic support until they are flush at one end.
That’s pretty much all there is to it. After soldering the components in place, I have a useful prototyping / development board to quickly get projects up an running.