{"id":14,"date":"2011-01-10T00:51:08","date_gmt":"2011-01-09T14:21:08","guid":{"rendered":"http:\/\/davidmonro.net\/blog\/?p=14"},"modified":"2011-01-10T00:51:08","modified_gmt":"2011-01-09T14:21:08","slug":"remote-temperature-monitor-project-breadboard-prototype","status":"publish","type":"post","link":"https:\/\/blog.davidmonro.net\/index.php\/2011\/01\/10\/remote-temperature-monitor-project-breadboard-prototype\/","title":{"rendered":"Remote temperature monitor project – breadboard prototype"},"content":{"rendered":"

So now I have all the bits (microcontroller chip, usb- 5v serial module to program it with, transmitter, receiver, another cheap usb-5v serial to build the receiver around, a DS18S20 and a bunch of passive components). I also have a double breadboard, and the circuit diagram for the arduino boards so I know roughly how to put one together (basing it on the stripped down “Pro”<\/a> model, in 5v 16MHz form). This means I can build it with the reset pin correctly tied to the usb-serial widget to auto-reset on sketch download etc.<\/p>\n

At first it all goes well; I get my bare ‘168 up and running with an LED attached, and download the blink code to it, and it blinks nicely. I plug a couple of DS18S20 units in and get temperature readings from them which look sane. I learn how to use the software serial library to drive a second serial bus (so I can use the hardware one for debugging and sketch downloading at the same time).<\/p>\n

However, when I try using the wireless devices, I can’t get anything out of the receiver. Zip. Zilch. Nada.<\/p>\n

Much headscratching ensues. I’m just about to give in and send the units back to littlebird (which would have been awkward since this was over the christmas break), when a final google search turned up a suggestion that the exact module I’m using may not be able to sink enough current to drive the microcontroller input pin. A trip to Aztronics<\/a> to get a cmos 4049 hex inverter, and I start getting output!<\/p>\n

Trouble is, its mostly rubbish. The receiver appears to be extremely noisy, especially if the transmitter isn’t actively transmitting. In addition, sometimes I appear to be losing a bit or so at the start of transmissions, leading to complete gibberish as the receiver gets out of sync with the transmitter. After fiddling around with different bit patterns, I discover that putting the sequence “U U U U U U U U ” at the start of my transmission almost always results in the receiver getting synced up OK before the actual message starts arriving.<\/p>\n

I also discover that having both the transmitter and receiver on the same breadboard means I need to not<\/strong> have any antenna wires, otherwise I don’t get anything but noise – I’m guessing the transmitter is completely overwhelming the receiver at this point.<\/p>\n

But at least the breadboard prototype seems to be working.<\/p>\n","protected":false},"excerpt":{"rendered":"

So now I have all the bits (microcontroller chip, usb- 5v serial module to program it with, transmitter, receiver, another cheap usb-5v serial to build the receiver around, a DS18S20 and a bunch of passive components). I also have a double breadboard, and the circuit diagram for the arduino boards so I know roughly how […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,7,4],"tags":[8,14,15],"class_list":["post-14","post","type-post","status-publish","format-standard","hentry","category-electronics","category-remote-temperature-sensor","category-sensors","tag-arduino","tag-electronics","tag-sensors"],"_links":{"self":[{"href":"https:\/\/blog.davidmonro.net\/index.php\/wp-json\/wp\/v2\/posts\/14","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.davidmonro.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.davidmonro.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.davidmonro.net\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.davidmonro.net\/index.php\/wp-json\/wp\/v2\/comments?post=14"}],"version-history":[{"count":0,"href":"https:\/\/blog.davidmonro.net\/index.php\/wp-json\/wp\/v2\/posts\/14\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.davidmonro.net\/index.php\/wp-json\/wp\/v2\/media?parent=14"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.davidmonro.net\/index.php\/wp-json\/wp\/v2\/categories?post=14"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.davidmonro.net\/index.php\/wp-json\/wp\/v2\/tags?post=14"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}