Cheapduino

I was tired of running heaps of wires between my Freeduino and the breadboard, so I made this simple "Cheapduino". It consists of a ATmega168, a 16Mhz resonnator and a 10kOhm pull-up resistor for the reset pin.

  • 10kOhm resistor from pin 1 to pin 7.
  • Wire from pin 7 to pin 20.
  • Outer legs of resonnator to pins 9 and 10.
  • Center pin of resonnator to pin 8.
  • Wire from pin 8 to pin 22.

When you set the Cheapduino up on a breadboard you connect ground to pin 8 or pin 22, and +5v to pin 7 or pin 20. You can also connect a reset-button between pin 1 and ground.

To program it I use a Freeduino with no chip, and connect the tx/rx- and reset-lines to the Cheapduino. The ATmega168 must ofcourse have the Arduino bootloader for this to work. It's also possible to set up an ICSP header on the breadboard and use an ICSP programmer.

that’s really cool! it very much simplifies the amount of wires needed to be run on the breadboard, and gives you much more room to work with! would this still be able to be placed in a chip socket?

would this still be able to be placed in a chip socket?

Sure it could.

Great, as a newbie (with some DIY electronics experience) I was looking for the right board to choose but then saw this.

my digital theory instructor would have an anurism if he saw that. There is a possibility moving traces over components introduces unwanted electromagnetic interference, (EMI) but if it works, more power to you.

I wouldn't worry too much about EMI. However I do recommend that you do wire all the Vcc pins together and all the ground pins together as per the AVR data sheet recommendations, not just some of them. Also it's recommended to have a .1 ufd cap wired between Vcc and ground.

Lefty

However I do recommend that you do wire all the Vcc pins together and all the ground pins together as per the AVR data sheet recommendations, not just some of them

According to the pinout I saw (found one on Sparkfun) GND is on pin 8 and 22, Vcc on pin 7 and 20. Those are connected together.

would this still be able to be placed in a chip socket?

Sure, no problem.

my digital theory instructor would have an anurism if he saw that.

:D That's the advantage of being an amateur - you can do things the wrong way and somehow it still works.

There is a possibility moving traces over components introduces unwanted electromagnetic interference, (EMI) but if it works, more power to you.

I have no problems with this setup. I wouldn't expect any either at just 16MHz.

Great, as a newbie (with some DIY electronics experience) I was looking for the right board to choose but then saw this.

You still need some way to program it. I use a Freeduino for this, but it shouldn't be hard to build a cheap interface around a MAX232.

... there are no decoupling capacitors............you need those... or you could have some funny stuff happen.

If you have some basic parts, there are transistor equivalents to the MAX232, you can find examples at SPARKFUN as well.

nice simple thing :slight_smile:
and yea u can make a simplbe ttl to rs232 converter easily enough.

for example
http://www.scienceprog.com/wp-content/uploads/2006i/RS232_ALT/interface_schematic.gif
just connect the db9 pin 4 to the reset line with a 1uf cap if u use that schemantic
there are plenty online. and one in the schematic on one of the olde serial arduinos i think.

I put together an arduino board with a similar concept, but more full-featured. It has all of the caps, pin 13 led, and ftdi header. The updated version adds reset button and power regulator. It connects to a breadboard through a wire-wrap socket, so all pins are available with the same footprint as the chip, and most of the components are under the chip, so it doesn't cover up half the breadboard like every other pcb.

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1239733868

this is just great. thanks. Isn't it possible to run the atmega at 8mhz without an external resonator?

I love the idea of freeing up breadboard space.