Tiny 2313 Experimenter’s Board

There is a new project on which I am working.  For years, I have been taken with development kits.  Since money has always been pretty tight, most of my interest has been in the lower-cost kits.  Also, as a teacher, I have worked for decades to try to teach beginners about electronics, robotics and computers (our tagline reads: Helping to Build a Better Engineer.)

This new project is a very low-cost dev kit to introduce students to microcontrollers using Atmel’s low-end ATtiny2313.  This is a chip that I often find myself choosing when I need a low-cost controller for a project.  The kit is designed to provide much of what an engineer needs to create a new project.  There are pushbutton switchers, LEDs, connectors for servo motors and a speaker.  The board even has a light detecting phototransistor and a thermistor (I may have gone too far with that, since the 2313 has no real analog input – we shall see about that in beta testing.)  All of this fits in a tiny 2″ by 2″ PCB and can mount on a 4-cell AA battery box (with room to spare.)  The target price for this board is around $30-$50, with a beginner’s introduction text included.  There may also be an offer for the bare board for those who would like to roll-their-own.

Basically, I wanted something that is portable, like my Pocket Development Kit (http://www.instructables.com/id/Build-a-PDK-Pocket-Development-Kit/,) and with all the peripherals needed to get started and learn.

Here is a picture of the Tiny2313 Experimenter’s Board, as it currently exists:

As you can see, the board uses a standard 10-pin STK-500 programmer.  There are many of these around, and I am currently evaluating one that I may be able to offer for under $10.  Also, since the STK programmer provides +5V, there is a jumper-switchable option to power this board from either an external battery (or power supply) or the attached programmer.

There is a reverse-polarity protection diode in-line with the battery input.  Yes, this will drop the input voltage by about 0.6V, but the Tiny2313V works just fine at those lower voltages.  This will affect the analog parts of the system, but that is something that I am still considering (also, we have a ‘X61 equivalent in development – the ATtiny26 family has several built-in real ADC (Analog to Digital Convertor) inputs on-board.

One thing that has yet to be determined is whether this is OK, as is.  With the Tiny2313’s analog comparator inputs (rather than true analog input,) the analog devices are only useful if the board has (or has access to) DAC (Digital to Analog Convertor) such as an R-2R circuit.  One change, consideration is whether to drop the servo motor connectors and replace them with a DAC, or to keep the servo interface.  This would lower the board’s value to robotics, but provide better analog capabilities.

Another possibility is to include a tiny breadboard and the resistors to create a simple R-2R DAC.  This would tend to lessen the all-included intent of this design – I really wanted something tiny that has everything needed to get started.  What do you think about these possibilities?  I am most interested in people who are wanted to just get started, or have taught these types of classes before.  Let me know!