Thursday, February 8, 2007

A 2051 thermometer experiment

Well this was mostly a "notice some unused components lying around and build something on impulse kind of thing"
Still have some 2051s left over from a previous order of around 5. Had a green, 4digit, 7segment led display which was of the dumb variety with each segment having separate pins in all the digits, no easy solution with 1 set of segment pins and a latch selector like here Also had two 8bit serial-in paralell-out shift registers so I used those to drive the last two of the four digits and wired up the middle segment of the second digit to a separate IO pin to use as a negative sign when it's freezing :-) For the temperature reading I use a DS1621 which I freesampled from Dallas/Maxim The thing top left is a 7805 and under the micro is a reset switch.

It looks really ghetto indeed but It works, and something like getting the more accurate value from the 1621 and sending it out on the serial port for temperature monitoring on a PC or controlling a fan with it wouldn't take long and would only be about 5 extra lines in BASCOM.

The code was based on the project linked above. It's here in case you're interested.