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Attached is some preliminary stuff I've put together about this logger, if anyone is interested. I still need to tidy up the circuit diagrams from the very rough handwritten things I have at the moment and write out a bill of materials, but the code, PCB layouts etc is all in the zip file below.
@JSHarris: Thank you for this! I'm tempted even though I'm maxed out on shop-bought sensors. I need to validate them: yes that's my excuse.
And the mystery newline is there again!
chrisb@delta:~ $ unzip -l Downloads/Logger\ files.zip Archive: Downloads/Logger files.zip warning [Downloads/Logger files.zip]: 1 extra byte at beginning or within zipfile (attempting to process anyway) Length Date Time Name --------- ---------- ----- ---- 152399 2012-02-16 18:10 Logger description.pdf 5496 2012-02-16 07:10 Sensor 8085 & 361.bas 14336 2012-02-16 17:54 Calibration factor calculation.xls 18614 2012-02-16 12:27 development test - single temp & RH module.bas 19187 2012-02-16 12:32 development test - two temp & RH modules.bas --------- ------- 210032 5 files chrisb@delta:~ $ od -c Downloads/Logger\ files.zip | head 0000000 \n P K 003 004 024 \0 \0 \0 \b \0 O 221 P @ 337 0000020 020 \n % 272 D 002 \0 O S 002 \0 026 \0 \0 \0 L 0000040 o g g e r d e s c r i p t i o 0000060 n . p d f 304 372 s 220 5 _ 227 256 215 226 m 0000100 333 266 361 224 m 333 266 m 333 266 m 333 266 m 273 352 0000120 ) 333 347 327 335 373 335 247 367 356 350 / 372 373 347 234 0000140 210 025 9 # G 216 9 362 276 r 256 225 261 r 334 I 0000160 * / , J 313 H 307 002 E 332 ? > 275 \b \v 305 0000200 H 300 @ ` g h \t 305 315 \r E 257 l 341 l m 0000220 B @ 321 305 d P , p W 006 342 316 343 343 356 t chrisb@delta:~ $
I've pretty much finished the logger now and just need to wire sensors around the house etc. It fitted into a fairly cheap, clear fronted plastic box easily enough, with room for a small power supply and the PP3 backup battery underneath. In the photo below it only has a single temperature and humidity module hooked up - it defaults to 0 deg C if sensors are disconnected.
The second and third photos are the finished temperature and RH modules. The circuit board is a snug fit into a bit of cable conduit and is held in place by a bit of foam double sided tape. Leaving the end open ensures the humidity sensor (the white circular thing) gets a good sniff of the air, whilst still being protected from damage.
These sensor modules could very easily have their on board code changed to send normal ASCII text strings to a PC or other form of measurement system if need be. They cost around £14 each to build, so aren't too expensive compared with other options for measuring temperature and humidity around a house.
I want dinky cheap-enough sensors like this on a 1-wire bus. I think we can do that without changing your circuit at all and just putting in the halfbee 'fake one-wire' code that Ericw has developed on navitron. Need to check PIC compatibility but so long as we can fit both the 1-wire implementation and the humidity-sensor-related code into the chip we should be in business.
Eric's code pretends to be a temp sensor in order to make it compatible with existing 1-wire tools, which has the advantage of simplicity. I'd much prefer it to use a new ID so it could be treated properly and not have an arbitrary scale, but that would be easy to fix if he opened it up (he hasn't yet).
This enhancement should definately go on the to-do list. 5V powered temp+humidty 1-wire sensors for under £20 would be great, and looks within our grasp.
Logger_files.zip doesn't include schematics in a useful form (just pics in the PDF). That would be good.
Thanks wookey. The reason the schematics are missing is simple, they were really rough hand drawn things in my lab book!
I've just scribbled down a neat'ish version for the sensor and have checked the code to see how much spare space there is in the sensor board ucontroller. The latest version of the sensor code is attached (as a text file) and takes up 238 bytes from a total of 2048 bytes that's available, so there's plenty of code space free to do other things with.
Edited to add that I've now drawn up the logger schematic and added that here.
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