Part 1- Abject failure-breaking the temperature sensors
To begin with I looked on YouTube but got confused with some of their setups and they were not using breadboards, or had LED screens which increased the complexity of the wiring. So I looked at the first tutorial and sort of looked at the breadboard/wiring layout and followed that (but missed the black wire to GPIO 6, so when I came to look in the /sys/bus/w1/devices/ directory there were no files there.
So I went on to tutorial 2 and tried to wire up to that one. I had all the wires but then started to reverse them and the temperature sensor started to get hot. I had 2 temp sensors and basically have moggerdored them both. I think I’ve burned them out.
The 2nd tutorial at least used Live/Ground and after reviewing the data sheet I can see NOW which pin should have gone where.
So for the time being an expensive mistake. $16 NZ down the drain and nothing to show for it.
I have ordered a multi sensor pack online to play with but that wont come for a few weeks, so I have time to dwell on being a bit less cavalier about the wiring.
Things to think about:
See if I can understand the wiring diagram first in relation to the sensors before buggering them up.
Do some testing with the breadboard or get thicker wires. Some of the wiring seemed very loose so I thought that there was not a circuit.
Maybe get some LED’s to put in part of the circuit to check that the connections do work.
Try tutorial 3 above. This one does not use breadboard but will be the final wiring for the sensors. Its also good for 2 or more sensors. So may be worth pursuing.
Now I have to wait for some more sensors and proceed more slowly
Maybe I was over confident with proceeding, although I did turn the Pi off while I did the first wiring up. I had such easy success with the camera module. Now I’m $16NZ poorer and no further ahead.
New sensors Friday 30th August
I bought a couple of DS18B20 online from a NZ outlet, they looked quite reasonable, they were the bare bones temperature sensor, a black blob with 3 wires sticking out, but I got done on delivery prices, so in the end not much less than what I could have got in Jaycar, these ones were about $6.50 with out the board and LED light. Ce la vie.
I ended up wiring the first one up wrong AGAIN. I seem to be dyslexic with the pins for some reason, anyway, if it gets hot and smells, its the wrong way around.
This time it created a sub-directory after adding the extra line in the config.txt file but it did not initially have the sensor directory. So that took a few re-boots to get those to work, but I finally got there.
I finally used a bit of a sticker to mark the Ground prong from the thermometer sensor and things went fine after that.
I now have 2 sensors working in parallel sending results to files w1_slave in the specific sensor directory.
That took a lot of breakages to get a couple of temperature sensors working. I can only get their output by interrogating the file, so it is a live temp. It is not saving any data anywhere at this point.
The next part of the process is to explore methods to log the data over time, say, take a reading every minute/5 minutes etc and store that data somewhere.
Also to send the data to another computer using MQTT or something similar. Initially I might use the cloud to act as a broker, then later install the broker on the RPi.
Overall a success for the first step, but it was not as simple as I thought. Lessons learnt? Be very careful about pins on sensors & wiring things up.