Tuesday, January 6, 2015

Make an ATTiny85 Progrsmmer and Development Board

I got a few of these small cheap chips from Atmel in the AVR family, like the arduinos. Not sure why I need cheap, with the atmega328p around $4, these tiny85s were about $3 when the STM32 ARM family of NUCLEO boards are only $12. That's over 100 times faster and already a development board. It is cheap enough to put in a project or two and just leave there.

But anyway, I have a few and a couple target projects that could use a small cheap controller. Like a fridge fan that turns a small fan on to control the temperature in a small compartment. Or an automatic shutoff for the cooling exhaust fan inside the generator room when the temp drops enough.

Everybody else is making clones, so here's a go. No, really I just need a way to program a few. My programming seems to be the kind that is, change a line of code, download it, test, repeat,...for days... so I need to be able to re-program the devices multiple times without hassle.

Poking around the web I find numerous posts about programming on a breadboard with a bunch of jumper wires either from a programmer or via an arduino. Also I found a few custom boards and even Sparkfun.com has the Tiny AVR Programmer for the ATTinyx5s.  But ordering things here to the Philippines is traumatic at best.

Since I already have the Adafruit USBtinyISP AVR Programmer Kit (and several others) I don't need a programmer, I need an adapter for it. I got most of my final ideas from Arvydas and his programmer.

I decided as long as I was soldering somethin up, it might as well have a few comnnectors so I can use a prototype board to test a design easily

Here is the strip-board diagram in Fritzing.

The bottom of my strip-boards are always ugly.
Starting from upper left is the 6-pin AVR programming header. I chose it because it has +5 and GND as well as the programming signals and can power the board. Next a red LED to show power to the board. Upper right is an LED tied to pin 4 for the default blink 'hello world' program. But with so few pins available, a jumper to disconnect the LED for pin 4 in case the application wants that pin. Below it is a reset switch.

Next across the bottom are headers, arduino like, bringing out each pin as well as an extra +5 and GND. There never seem to be enough. I also thought it could support a mini shield too.

AVR AT Tiny85  programmer and development board.

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