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by TerryC65
Sun May 14, 2017 12:41 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Using 1-Wire to Monitor Data from Many Distributed Sensors
Replies: 14
Views: 1774

Re: Using 1-Wire to Monitor Data from Many Distributed Senso

This is what the people who make 1-wire chips have to say: https://www.maximintegrated.com/en/app-notes/index.mvp/id/148 Thanks I had spotted that, but my question was really about the drive capabilities of the Pi. From the link: The master-end interface greatly influences the allowable size of a 1...
by TerryC65
Sun May 14, 2017 12:32 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Using 1-Wire to Monitor Data from Many Distributed Sensors
Replies: 14
Views: 1774

Re: Using 1-Wire to Monitor Data from Many Distributed Senso

ESP8266s don't have an antenna. They have a funky circuit board trace. Raspberry Pi Zero Ws don't have an antenna. They have an entirely mysterious triangle shaped thing on the circuit board that does some RF magic. I know, but we would need an antenna because the electronics are likely to be insta...
by TerryC65
Sun May 14, 2017 11:25 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Using 1-Wire to Monitor Data from Many Distributed Sensors
Replies: 14
Views: 1774

Re: Using 1-Wire to Monitor Data from Many Distributed Senso

.....running as MQTT data aquisition publishers and an MQTT subscriber on the master. You can also run MQTT with the publisher on the master and subscribers on the remotes to send command and control messages back the other way. The remotes are going to need 5V power, but you'll gain with not havin...
by TerryC65
Sun May 14, 2017 10:27 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Using 1-Wire to Monitor Data from Many Distributed Sensors
Replies: 14
Views: 1774

Re: Using 1-Wire to Monitor Data from Many Distributed Senso

Get an ESP8266 or RPiZW running as the remote servers. You'll have those ESP8266s or RPiZWs running as MQTT data aquisition publishers and an MQTT subscriber on the master. You can also run MQTT with the publisher on the master and subscribers on the remotes to send command and control messages bac...
by TerryC65
Sun May 14, 2017 9:14 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Using 1-Wire to Monitor Data from Many Distributed Sensors
Replies: 14
Views: 1774

Using 1-Wire to Monitor Data from Many Distributed Sensors

Hi, Our River System control development at our local Model Town has progressed to considering communications. We will have a number of level and flow sensors distributed around the site, some of which will be up to 100 metres from the master controller, which will almost certainly be a Pi 3. We are...
by TerryC65
Thu May 04, 2017 12:27 pm
Forum: Automation, sensing and robotics
Topic: Fluid Level Sensing
Replies: 16
Views: 4699

Re: Fluid Level Sensing

Pressure sensors are used in washing machine for water level. Yes. I had noticed that these are available, but I wasn't sure if they were a pressure sensing device or a simple pressure switch. Time domain RF reflectance sensors are used for fluid levels. Adafruit have a laser Time of Flight sensor ...
by TerryC65
Thu May 04, 2017 10:06 am
Forum: Automation, sensing and robotics
Topic: Fluid Level Sensing
Replies: 16
Views: 4699

Re: Fluid Level Sensing

Yes it would give rrneous readings if and when it happened, but I have not experienced such problems in practice, and it's very easy to eliminate false readings in software. With cheap sensors you would have to eliminate the spurious readings anyway. My main concern would be if the acoustic signal ...
by TerryC65
Thu May 04, 2017 9:52 am
Forum: Automation, sensing and robotics
Topic: Fluid Level Sensing
Replies: 16
Views: 4699

Re: Fluid Level Sensing

I'm also going to be close by, 26 June onwards for a week (not camping - too old for that - Chalke Valley History Festval) so if you're at the Model Town when we visit I'll say Hi. I have to say that I'm unlikely to be there at that time; I only normally attend during the Open period if something h...
by TerryC65
Wed May 03, 2017 12:16 pm
Forum: Automation, sensing and robotics
Topic: Fluid Level Sensing
Replies: 16
Views: 4699

Re: Fluid Level Sensing

This sounds like an impressive Model village! I'll have to visit if I can when i go camping in Dorset this year. Well. As a volunteer there, I can only suggest that you won't be disappointed. The attraction is run as a charity. There are only three full-time staff, plus the people in the cafeteria....
by TerryC65
Wed May 03, 2017 9:17 am
Forum: Automation, sensing and robotics
Topic: Fluid Level Sensing
Replies: 16
Views: 4699

Re: Fluid Level Sensing

Unless you need super accuracy, Conductivity probes are the simplest way to measure approx levels. One probe detects tank full, One Medium and another almost empty. The probes are nothing more than two nails seperated by small distance. and you measure the conductivity between the two nails. If the...
by TerryC65
Wed May 03, 2017 9:10 am
Forum: Automation, sensing and robotics
Topic: Fluid Level Sensing
Replies: 16
Views: 4699

Re: Fluid Level Sensing

How much are laser distance devices coding now? In a water butt you could create a float on say a rod that you can reflect off. Or some strain gauge type float device (float connected wire string to a gauge at the bottom of the butt). Or weight as mentioned above (external strain/pressure plates/se...
by TerryC65
Wed May 03, 2017 8:57 am
Forum: Automation, sensing and robotics
Topic: Fluid Level Sensing
Replies: 16
Views: 4699

Re: Fluid Level Sensing

The weight of the water butt will be proportional to the amount of water in it. If you know the capacity and the weight, you can work out the level - if a 100l butt weighs 100kg (minus the weight of an empty butt) it's full. Now this isn't a bad idea!! In fact the butts are probably around 200 litr...
by TerryC65
Wed May 03, 2017 8:41 am
Forum: Automation, sensing and robotics
Topic: Fluid Level Sensing
Replies: 16
Views: 4699

Re: Fluid Level Sensing

Maxbotic do IP67 sonars: https://www.maxbotix.com/Ultrasonic_Sensors.htm?1b8106 Coo... Did you see the price of those things? Our budget for materials is about 1/10th of the cost of a single sensor. :shock: But you probably don't need the performance for this application. If I was doing this, I'd g...
by TerryC65
Mon May 01, 2017 11:54 am
Forum: Automation, sensing and robotics
Topic: Fluid Level Sensing
Replies: 16
Views: 4699

Fluid Level Sensing

Our local Model Town has an ongoing Project to improve the sustainability of water in the 'Model' river. This follows the route of the real River through the Model Town and has, until now, been managed and maintained by volunteers and staff turning the mains water tap on and off. We have mapped out ...
by TerryC65
Tue Apr 11, 2017 12:18 pm
Forum: Advanced users
Topic: My Script appears to reset itself after extended running
Replies: 2
Views: 451

Re: My Script appears to reset itself after extended running

you will never get water out - leave a vent at the bottom for any condensation to drip out. I would personally suspect a dodgy connection .... / power issue I'm not expecting there to be much condensation, if any. The ammo box is completely sealed and we'll only be running the system during the sum...
by TerryC65
Mon Apr 10, 2017 1:17 pm
Forum: Advanced users
Topic: My Script appears to reset itself after extended running
Replies: 2
Views: 451

My Script appears to reset itself after extended running

Hi, I deployed a Python script to simulate bells and chimes at our local Model Town and also to play organ music in the Chancel. This was tested fairly extensively at home, but there were limitations to what I could do, because some of the hardware, by necessity, had to be installed into the model. ...
by TerryC65
Sun Mar 26, 2017 12:10 pm
Forum: Python
Topic: Python Script Only Works in IDLE
Replies: 1
Views: 389

Python Script Only Works in IDLE

Hi, I have a small Python script that I need to run headless. It's function is to sound the bells at fixed times of the day (eg, church chimes in a model town) and also to play music and other sounds to order. The chimes are triggered by function calls in apscheduler entries and the music and other ...
by TerryC65
Sun Mar 26, 2017 10:17 am
Forum: Advanced users
Topic: Mount USB Stick at Bootup
Replies: 3
Views: 1466

Re: Mount USB Stick at Bootup

Use Stick a line in /etc/fstab with PARTUUID=vvwwxxyy-0n /home/pi/WMT ext4 defaults 0 0 (Change to ntfs-3g or vfat or whatever if it's not ext4 formatted) Actually, disregard my last post; I'd left out the filesystem entry (vfat in this case). Your suggestion gave me the clue. My first attempts had...
by TerryC65
Sun Mar 26, 2017 10:11 am
Forum: Advanced users
Topic: Mount USB Stick at Bootup
Replies: 3
Views: 1466

Re: Mount USB Stick at Bootup

DougieLawson wrote:Use sudo blkid /dev/sda to find a UUID or PARTUUID for the partition you want to mount.
I was trying to avoid using UUID so that staff members can replace the USB Stick (should it fail) without having to know how to edit fstab; just change the label on the stick.
by TerryC65
Sun Mar 26, 2017 10:05 am
Forum: Advanced users
Topic: Mount USB Stick at Bootup
Replies: 3
Views: 1466

Mount USB Stick at Bootup

Hi, For my project, to restore the bells and music to the local Model Town Minster, I want the system to run headless and so I won't need (or want) to run the desktop. The Python code is now working when tested in IDLE, so all I have left to do is start the script automatically at boot-up. (I will a...
by TerryC65
Tue Mar 21, 2017 12:29 pm
Forum: Beginners
Topic: Getting DNS on a Pi 3 Webserver in a Walled Garden
Replies: 1
Views: 402

Re: Getting DNS on a Pi 3 Webserver in a Walled Garden

Replying to myself, because I seem to have fixed it. It suddenly occurred to me that the phone was trying to get to Google because it sees 'WMT' as a search term rather than a URL when it is typed into the address bar. I changed the name of the domain to 'WMT.com' and it now works. One final questio...
by TerryC65
Tue Mar 21, 2017 11:50 am
Forum: Beginners
Topic: Getting DNS on a Pi 3 Webserver in a Walled Garden
Replies: 1
Views: 402

Getting DNS on a Pi 3 Webserver in a Walled Garden

Hi, I am trying to set up a Webserver at our local Model Town, so that visitors can listen to Audio Guides and fill in an online Quiz using their phones or tablets. However, I'm having problems with DNS setup. The hardware is: 1. Pi 3 with UPSPico for power cuts. 2. TP-Link TL-WA7210N Outdoor Wirele...
by TerryC65
Thu Mar 16, 2017 9:32 am
Forum: Troubleshooting
Topic: GPIO Pins seem to have no Oomph
Replies: 11
Views: 1326

Re: GPIO Pins seem to have no Oomph

PiGraham wrote:I think you need this:

Code: Select all

GPIO.output(7, GPIO.HIGH)
That could explain what you are seeing, where you are switching between input and output mode instead of turning an output on and off.
Crumbs! How did it ever give me pulses when the pin wasn't loaded! Thanks for pointing out my dumb mistake.
by TerryC65
Thu Mar 16, 2017 7:50 am
Forum: Troubleshooting
Topic: GPIO Pins seem to have no Oomph
Replies: 11
Views: 1326

Re: GPIO Pins seem to have no Oomph

Your load is a MOSFET gate, which behaves as a capacitor. You need a resistor to discharge that capacitance and turn off the device when not driven. One way to look at that is as the input of the MOSFET needs a pull-down. What is your circuit? What MOSFET are you using. Yes it is in my project, but...
by TerryC65
Thu Mar 16, 2017 7:39 am
Forum: Troubleshooting
Topic: GPIO Pins seem to have no Oomph
Replies: 11
Views: 1326

Re: GPIO Pins seem to have no Oomph

I get the feeling that there is a mistake somewhere, where you don't switch the output high or low but instead as low or as input with a weak pullup (50K). You could try to add a stronger pullup (say 2K2) to see what happens. I'm not sure that I understand what you mean when you say 'adding a stron...

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