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by stevend
Wed Nov 27, 2019 10:57 pm
Forum: Other projects
Topic: Custom RPI Music Reader for playing piano
Replies: 2
Views: 421

Re: Custom RPI Music Reader for playing piano

Have a look at this project:
https://www.leferguson.com/musicalpi-source-code/ (there are several blog posts about it, and a forum thread here somewhere)
Code is at: https://github.com/Linwood-F/MusicalPi
by stevend
Thu Oct 24, 2019 12:21 pm
Forum: Automation, sensing and robotics
Topic: Automatic Gate Using Rpi
Replies: 8
Views: 6813

Re: Automatic Gate Using Rpi

Some (most?) gate controllers have one or more external inputs to which you can connect buttons for open/close etc. So you can have a hard-wired button in the house to open the gate, for example (useful when the battery in the remote goes flat!). This may also give you more control options than goin...
by stevend
Sat Oct 19, 2019 11:50 am
Forum: General discussion
Topic: Choosing the correct output type in wind sensor module
Replies: 5
Views: 340

Re: Choosing the correct output type in wind sensor module

RS-485 is a multi-drop differential transmission system. You can have multiple transmitters on a bus, with just one at a time having its output enabled. Two wires are used to send a signal; both are driven; one to 0V, and another to positive voltage (typically 3-5V). The receiver measures the voltag...
by stevend
Sun Oct 13, 2019 3:46 pm
Forum: Automation, sensing and robotics
Topic: Is there an i/c? GPIO-controlled spdf-like switch to switch between 2 methods of controlling a transistor?
Replies: 3
Views: 1113

Re: Is there an i/c? GPIO-controlled spdf-like switch to switch between 2 methods of controlling a transistor?

You can make the LDR-based switch less "noisy" by using a comparator-type circuit with some added hysteresis. Probably the simplest way is to use a digital chip of the 74HCT14 type. In simple terms, if its input starts at 0V, as the voltage level increases through (say) 1.6 volts, the output will ch...
by stevend
Sat Sep 07, 2019 8:31 pm
Forum: Automation, sensing and robotics
Topic: safe protocol for cheap 433MHz transceiver
Replies: 8
Views: 562

Re: safe protocol for cheap 433MHz transceiver

At one level the transmission medium is irrelevant. So exclude the 433MHz bit from your searches. It's quite possible that Joan's suggestion of VirtualWire is all you need (look closely at the detail to see how it works, and whether it handles errors sufficiently well for you). Otherwise, if you hav...
by stevend
Sun Jul 28, 2019 9:59 pm
Forum: Off topic discussion
Topic: big hands
Replies: 9
Views: 2779

Re: big hands

Try searching for "screw gripper" Examples: https://uk.rs-online.com/web/p/screwdrivers/0547975/ https://www.kctoolco.com/wera-073680-screw-gripper-attachment-set-for-insulated-screwdrivers/ https://www.amazon.com/Felo-0715750078-Phillips-Screwdriver-Gripper/dp/B000E60ODS/ref=sr_1_3?keywords=Screw+G...
by stevend
Tue Jan 01, 2019 8:46 pm
Forum: Automation, sensing and robotics
Topic: Relay Line out voltage causing voltage on line in
Replies: 31
Views: 2287

Re: Relay Line out voltage causing voltage on line in

I think I have a problem with voltage noise passing between supposedly isolated parts of a relay & don't know how to get rid of it. I have recently bought a standard 5V relay module board (8-channel)* and can control it without issue using an mcp23017 connected to the pi (3). However, when I connec...
by stevend
Thu Dec 20, 2018 9:42 pm
Forum: Automation, sensing and robotics
Topic: Maximum switch count/current
Replies: 5
Views: 1818

Re: Maximum switch count

of course you could always 47K and 68K resistor which would reduce the current by a factor of 10 I'd recommend sticking to the values pcmanbob initially suggested (or, at least, around those values - maybe even slightly lower values, as long as you keep the ratio the same). They are the same order ...
by stevend
Sun Dec 16, 2018 8:34 am
Forum: Automation, sensing and robotics
Topic: DS18B20 randomly missing connection
Replies: 3
Views: 910

Re: DS18B20 randomly missing connection

I suspect the cable length is a bit long for a simple pullup; especially the star configuration. You could try rewiring all the sensors in a 'daisy chain' along one piece of wire, and if the wiring permits you could split the pullup resistor into two higher value resistors, with one at the Pi and th...
by stevend
Sun Dec 16, 2018 8:28 am
Forum: Off topic discussion
Topic: Why Avoid BASIC on RPi?
Replies: 2312
Views: 125888

Re: Why Avoid BASIC on RPi?

.... and there is no longer any need to try and force code into a smallest memory footprint. What about small embedded systems? (Things like the small AVRs, small ST32 family - these have as little as a few kilobytes of program memory, and a kilobyte or less of RAM). Sometimes the driver for using ...
by stevend
Sat Dec 01, 2018 7:32 pm
Forum: Automation, sensing and robotics
Topic: Tradfri light sunset switch on
Replies: 1
Views: 1309

Re: Tradfri light sunset switch on

If you don't want to be reliant on a working internet connection, its possible to calculate sunrise/sunset yourself. See: https://stackoverflow.com/questions/19615350/calculate-sunrise-and-sunset-times-for-a-given-gps-coordinate-within-postgresql I've attached the variant of the code from that link ...
by stevend
Sun Nov 25, 2018 8:42 pm
Forum: Off topic discussion
Topic: Why Avoid BASIC on RPi?
Replies: 2312
Views: 125888

Re: Why Avoid BASIC on RPi?

There was the BDSC C compiler by Leor Zolman for CP/M. That required a full up 64K machine I think. There was Tiny Pascal for the TRS-80. There was a standards-compliant Pascal Compiler for the Z-80 by a small British company called Prospero Software - ran under CP/M. Very good quality, with the ab...
by stevend
Sat Nov 17, 2018 9:24 am
Forum: Raspberry Pi Desktop for PC and Mac
Topic: Missing taskbar on fresh install
Replies: 2
Views: 3864

Re: Missing taskbar on fresh install

Looks like this is sorted in latest release (13th November) - just installed succesfully
by stevend
Wed Nov 14, 2018 1:23 pm
Forum: General discussion
Topic: How Raspberry Pi work with DMX512 RGBW led strip
Replies: 8
Views: 515

Re: How Raspberry Pi work with DMX512 RGBW led strip

So a nifty idea if at a sensible price, but not that different from NeoPixels (which also make each LED individually controllable). The Dotstar range from Adafruit look to be rather easier to drive than the Neopixels (SPI-like interface at any speed, rather than a timing-critical interface) (Not tr...
by stevend
Sun Nov 11, 2018 2:58 pm
Forum: Automation, sensing and robotics
Topic: Home Automation requirements match
Replies: 16
Views: 2252

Re: Home Automation requirements match

that open radiator and thermostat is what most boiler fitter/heating people have quoted too. Which is odd as it is one room controlling the whole system, so you just set that room to 30decC to turn the heating on and let the TRV's do their job. One room gets blindingly hot. The hallway usually in m...
by stevend
Sun Nov 11, 2018 9:38 am
Forum: Automation, sensing and robotics
Topic: Home Automation requirements match
Replies: 16
Views: 2252

Re: Home Automation requirements match

You could look at https://novo-heat.com/ for valves. Not sure whether anything has shipped yet, but the backer price is very reasonable, and they don't even need batteries!
by stevend
Thu Nov 08, 2018 11:16 pm
Forum: Automation, sensing and robotics
Topic: Home Automation requirements match
Replies: 16
Views: 2252

Re: Home Automation requirements match

stevend: Found this, and installed it, looks like it is possible to set temps without having to create 00s of data points. Rules based system adds to flexibility. https://www.home-assistant.io/components/climate.zwave/ Thanks - looks like its come on a bit since I last considered it. Just had a qui...
by stevend
Wed Nov 07, 2018 1:33 pm
Forum: Automation, sensing and robotics
Topic: Home Automation requirements match
Replies: 16
Views: 2252

Re: Home Automation requirements match

Both of the below points are part of the same "problem": It doesn't (as far as I've found) have the ability to get a number of values from a sensor with a single MQTT subscription Please elaborate - single MQTT sub? MQTT allows you to subscribe to a topic with a wildcard - heating/valves/1/#, for ex...
by stevend
Tue Nov 06, 2018 10:47 pm
Forum: Automation, sensing and robotics
Topic: Controlling an RF thermostat
Replies: 15
Views: 3112

Re: Controlling an RF thermostat

Has anybody used any kind of 868 MHz transceivers/transmitter & receiver pair before with the Pi? I did find this pair of transmitter/receiver modules very cheap: https://www.rfsolutions.co.uk/radio-modules-c10/hoperf-fm-transmitter-module-868mhz-smt-package-p651 https://www.rfsolutions.co.uk/radio...
by stevend
Tue Nov 06, 2018 8:28 pm
Forum: Automation, sensing and robotics
Topic: Home Automation requirements match
Replies: 16
Views: 2252

Re: Home Automation requirements match

I have a system where everything uses MQTT for communication, and you'll find that a good medium for any 'special' sensors you might do using esp8266 or other networked devices. At present I'm using Openhab 1, which works, although the GUI is a bit lacking (and its been superceded). I've been lookin...
by stevend
Tue Nov 06, 2018 8:10 pm
Forum: C/C++
Topic: serial port problem
Replies: 7
Views: 2628

Re: serial port problem

1. Are you confident that the data bits and parity are correctly set for the BME680? 2. There's a possibility that cfmakeraw() might override your prior settings (https://linux.die.net/man/3/cfmakeraw) 3. These are the key routines I used to receive serial data: /** * Read a line of data from consol...
by stevend
Tue Nov 06, 2018 8:04 pm
Forum: Automation, sensing and robotics
Topic: Controlling an RF thermostat
Replies: 15
Views: 3112

Re: Controlling an RF thermostat

Most thermostats operate on 24V AC supplied by the HVAC system, and only reasonable care in wiring them is necessary - mains thermostats do exist but are becoming increasingly rare. You should turn off the HVAC system at the furnace/circulator before working on the thermostat, but this is more to a...
by stevend
Tue Nov 06, 2018 1:47 pm
Forum: Automation, sensing and robotics
Topic: Controlling an RF thermostat
Replies: 15
Views: 3112

Re: Controlling an RF thermostat

I thought the best way to go about this would be to get an RF transceiver (868 MHz is what my thermostat uses) to sniff the signals from my thermostat controller and then emulate those using the transceiver. I do have one question with this approach if anybody could answer, would the heating go out...
by stevend
Thu Oct 25, 2018 8:01 pm
Forum: General discussion
Topic: Subnet mask. ?
Replies: 4
Views: 1057

Re: Subnet mask. ?

My main network ip address' are 192.168.35.xxx, I'd like to setup the new pis on 192.168.36.xxx. What I can't find is a subnet setting anywhere. I've found one post that mentions adding the setting to the dhcpcd.conf file, but I don't use DHCP for the pis, there are too many and I'm not having them...
by stevend
Wed Oct 24, 2018 12:33 pm
Forum: Other projects
Topic: Target training for fencing
Replies: 10
Views: 1955

Re: Target training for fencing

If the buttons don't give you the accuracy you want, consider a resistive touch screen. You can sometimes buy them separate from a display. And maybe there's some other product using similar technology which is more suited to your intended purpose ("resistive pressure mat", maybe?) You'll need a sui...

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