I've drawn the electrical schematic (also with the corresponding Arduino pins from Arduino.cc):
Now for the best part - I priced the components (including a DIP socket for the ATMega8) from Jameco.com it comes out to $5.73! (8 pennies less if you don't care to have the power LED)
From what I can gather, it has no serial I/O, so complex sensors are out, but for simple read a sensor, take an action it doesn't get any better than this!
I'm hoping that it'll be as simple as swapping out the ATMega chips on an existing Arduino to burn the bootloader, then download your program. Then simply put in the ATMega chip and power up. Not 100% sure, I'll have to check the bootloader stuff on Arduino.cc
The best thing here is you won't have to waste your $30 Arduino for simple stuff!
Just had a thought - the reset switch and 10k resistor shouldn't be needed if this is being used as a dedicated device (once the program is written and loaded it should never change). Infact it would prevent accidential erasing by removing it (and reducing the over all price by 53 cents!)
ReplyDeleteAnother thought - you will still need to hook everything up together. So, it'll increase the price accordingly (small generic PCB, or if you're feeling super economical, just solder hook up wire everywhere!)
big oops - schematic is missing something:
ReplyDeletepin 7 on the ATMega should be connected to OUT on he 7805
pin 8 on the ATMega should be connected to GROUND
(and actually, a reset switch shouldn't erase the program, it should just do exactly that - RESET it, so ignore the first statement from comment #1)