The HalfBee project begins!

[StBarnabas]

List
As some of you may be aware I have been thinking about sensor networks for some time and am currently using 1-wire due to its ease of use and cheapness. 1-wire masters such as the ds9490R from homechip are c £15.00 and temperature measuring slave devices such as the DS18B20 can be purchased for c £1.00 each (but you may need to shop around as the price at RS has about doubled over the past year).  It is also possible to implement master devices on Arduinos and PICs etc. Which are much cheaper.

There is a need however to measure other parameters such as solar irradiation, flow rate, humidity, wind speed and direction etc. Such sensors are not normally cheap. My own needs involve monitoring the behaviour of
1) my Navitron solar  water/ASHP  system– temperature sensors, flow meters and electrical power
2) my Navitron PV array – Irradiance sensor + PV panel temperature (my GTI logs a lot of data)
3) my GSHP -  need temperature, flow and electrical power
This thread is attempt to make sensor networks available to anyone who is interested. There has been a lot of work done by a number of people first and foremost by EricW, but with other help from Meliffera, Wyleu, Wookey and others.

Over the next few months I hope to publish “best practice” regarding sensors, starting with the flow sensor.
I have gone for an RS 257-133. This is sadly about £20 but comes with standard 15mm connectors. Which I have been able to plumb into my cold feed to my immersion tank with minimal effort. KenB has recently found a 22 mm flow sensor from China  which I would like to try out.
This is interfaced to one of Eric’s 1-wire PIC 12F683 clones his DS2423. I have modified this very slightly as the recommended LED current on the Flow sensor is 30mA and the PIC12F683 can drive LEDs directly (25mA).  Essential pin 7 is turned into an output and set high.  
The great thing about this setup is that the chip count is one and not even resistors are needed.
I attach a few photos using flickr first time I have done this so I hope this works....


A collection of sensors including a very posh irradiance sensor and the flow sensor



Some data on the flow sensor




Connections to the flow sensor



The PIC connections




LogTemp counts




Hmm... not loading this images correctly there must be a way to get them visible on the screen without clicking etc...

Edit 9:00 29/7/10 Thanks Ted hope they all appear now

[Ted]

Sean, to embed images use code like this

Code:

[img]http://farm5.static.flickr.com/4089/4837466327_6c0997a210.jpg[/img]

but that must end in a recognised format e.g. jpg

[Amy]

Pardon me Sean for crashing your thread but I guess this is a place of accumulated wisdom

Is there a flow meter monitor which can log a cumulative value?

[Baz]

Following the enthusiasm for Arduinos on this forum I have been starting to look at them.
Bunch of sensors here.
http://www.nuelectronics.com/estore/index.php?main_page=index&cPath=7&zenid=a2db953382850ed8a1a2548b7c48bc19

Dedicated flow loggers tend to be expensive.
You could couple up the flow sensor to a counter like one of these.
http://www.quasarelectronics.com/counters.htm
There used to be cheap little cmos counters like clocks at Maplin but they don't do them now. A bicycle odometer might work.

[StBarnabas]

Ted
thanks have now gotten the hang of this I think. Now using Apple Snow Leopard so a bit of a learning curve.

Amy
Yes mechanical meters can be purchased quite cheaply 2nd hand (c £15) , but meters which data log tend to be expensive (>£100). The meter chosen produces pulses at c 1200 pulses per litre which are accumulated  on a counter in the PIC which can then be read over the sensor network using 1-wire protocol. There is no battery backup at present so if the power fails than the counter resets to zero. The PIC has some non volatile memory so it might be worth backing up the counter values periodically, but for my purposes, I just want to see if my system is performing correctly.

Baz
many thanks. Yes I have recently become aware of NuElectronics and there are some very nice sensors on the site, particularly the DHT11 Humidity and Temperature sensor at £4.50. I am also aware of Arduinos and in particularly the fine work KenB and others are doing.

The thrust of HalfBee at present is at the sensor end. What I simultaneous want to do for one of my systems  for example is to datalog about 20 channels (about once every 15 secs). 14 or so of these channels will be temperature (indeed the temperature network has been running for about a year). To that I want to add flow, electrical power and a batch of irradiance sensors. The system is currently using 1-wire protocol, which has 1 master device and as many slave devices as needed (there is a limit of several hundred I understand).

I am looking for a cheap counter which can also be connected directly to the 1-wire bus. The PIC is chosen because

I have paid 72p for mine - still have a large bag. (and still happy to send free PICs to interested parties).
It can be programmed to implement the 1-wire protocol so can just plug into the existing data network
It can be programmed to act as a dual counter
It can drive LEDs directly at 25mA so no need even for resistors.

Hence for minimal cost a pulsed flow meter can be turned into data logged flow meter. Sorry if I did not make myself clear earlier.

[Amy]

Thanks Sean

I was thinking maybe its possible to count water in and out in just the same way battery useage can be monitored by counting whats been charged into the bank against whats been taken out to give a running score.

[Baz]

BTW if you are using a full pc to record stuff have you seen Misterhouse.
http://misterhouse.sourceforge.net/
Their forum often discuss sensors too. (it isn't as dedicated to x10 as it appears at first glance. There is a substantial 1wire element)

[ericw]

HalfBee Humdtity & Temperature Sensor.

The latest addition to HalfBees  is a very low cost humidty and temperature sensor using the DHT11. The unit consists of A DHT11, one resistor and the programmed PIC so the overall cost is not much more than a fiver

To the 1 wire bus the HalfBee looks like two DS18B20's, one outputting the temperature and the other the Relative Humidity as a psuedo temperature. This can be plugged onto the bus and is readable by any 1 Wire software that can read temperature without additional programming.

The graph below shows the effect of turning on the shower in the bathroom.

[ericw]

Amy,
Most flow sensors consist of a crude turbine which is spun by the flowing water, as only one sensing element is used it is not possible to sense in which direction the turbine is turning. You would need two sensors (optical or magnetic) to work out which way it was turning and hence the direction of flow, to be able to do what you want.

[StBarnabas]

Eric
that was fast work. I hope the code will be generally available? Well done. Humidity sensors have been on my mind for a while and this is a very elegant solution.
Sean

[Amy]

Amy,
Most flow sensors consist of a crude turbine which is spun by the flowing water, as only one sensing element is used it is not possible to sense in which direction the turbine is turning. You would need two sensors (optical or magnetic) to work out which way it was turning and hence the direction of flow, to be able to do what you want.

I was thinking about a paddle wheel on both the fill and outlet pipes, both wired into a counter.

[KLD]

Eric, one from the numpty here: the DHT11, is that just the sensor? I only googled it quickly, the top link is to nuelectronics, and they explain it as if the 1-wire stuff is included in the DHT11? Or did they replicate (steal?) what you did?

Klaus

[ericw]

Klaus,
The DHT11 (from nuelectronics) contains two sensors and a processor. As it only has 3 pins it does output the data on a '1 wire bus' but not with the same specification as the standard (Maxim) one. The timing and format are different and it does not have any facility for addressing so you are limited to one sensor per master I/O line.

Sean,
I'll send you the code as usual.
I might also do a version that would mimic the Hobbyboards HIH-3610/DS2438 setup, but it would be a bit 'around the houses' as the numeric humidity output of the DHT11 has to be converted to 2 voltages, which are then read from the 1 wire bus by the master software which uses them to calculate the humidity value.

[StBarnabas]

Amy

This would naturally be possible but the inflow is often high pressure 15 or 22mm and the outflow may be low pressure waste pipe? Also if the water is dirty the sensors may not work very well?

Klaus
Eric please correct me if I'm wrong
whereas the DTH11 senors are described as 1-wire this simply means that one wire and ground needs to be connected to the Arduino. What Eric has done is to rewrite the interface form  the sensor to a PIC rather than Arduino and to marry that with the pic 1-wire slave code such that it looks like a dallas 1-wire device.
This is very useful as I have been looking around for a sub £5.00 humidity sensor for some time.

Sorry was just posting this when Eric got in first!
Eric thanks for the offer of the code very much appreciated as ever
Sean


Sean

[Amy]

Nooooooooo

Fresh water into the tank, tote up the score then subtract whats used as its pumped out of the tank to the fawcets.

That gives a real time accurate contents total.
The only paddle switches ive found are all high spec food industry ones which cost way too much.