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Friday, 3. August 2007
/RESET Pullup for Tiny15L
rsbohn
11:37h
I'm building a coin-flip device using the Atmel ATtiny15L. I bought a few way back when I got my Butterfly from Digikey. Anyway, I could program the chip just fine, but it wouldn't ever start running. I don't know what made me think of it, but I tied the reset line HIGH and it started working! I guess the 15L doesn't have an internal pullup on the /RESET line, so it was just floating. I didn't have this problem with the Tiny13 or Tiny2313 chips. The coin-flip is fun. You push a button and the two LED's start flashing, then they slow down and stop on one: Green for heads, Red for Tails. It waits a bit, then shuts everything down. Push the button and it wakes up and does another flip. I'll have to check the current drain while it sleeps, but I think it will not be too much. I leave the counter running on the chip, I think it makes it more likely to seem random. I sample the lowest bit of the counter when you release the button, and the counter is fast enough that you have about a 50/50 chance of getting a one there. The rest of the flashing is just for show. I'm planning to build this in permanent form over the weekend. Maybe I'll build a second one as a gift.
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8141 days of detection
mod: 12/3/08, 5:42 AM days of detection... PMOG owner
BiographyRandall Bohn lives in Orem, Utah, USA. He works as a Software Quality Engineer. He is a big fan of the AVR line of microcontrollers. He has been in the computer industry since 1989. Randall is married and has three children. rsbohn can be reached via gmail.com. status
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