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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: 1490

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: 1676

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: 757

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: 94976

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: 989

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: 94976

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: 3751

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: 7
Views: 243

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: 1649

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: 1649

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: 1649

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: 1649

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: 13
Views: 1969

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: 1649

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: 2396

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: 13
Views: 1969

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: 13
Views: 1969

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: 558

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: 1653

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...
by stevend
Fri Oct 19, 2018 7:38 pm
Forum: HATs and other add-ons
Topic: Is the PoE HAT really class 2?
Replies: 2
Views: 1435

Re: Is the PoE HAT really class 2?

Burngate wrote:
Fri Oct 19, 2018 6:20 pm
I'm no expert, and I can't find any reference to such low power ranges on the Wikipedia page.
Second table

It does look as if a Pi is more likely to be Class 3 than Class 2 - in fact, right at the limits of a Type 1 device. It will depend a bit on the peripherals powered.
by stevend
Wed Oct 17, 2018 12:34 pm
Forum: General discussion
Topic: Updated FAQ page.
Replies: 22
Views: 2188

Re: Updated FAQ page.

Apparently still available (although maybe only as a download):
https://www.theregister.co.uk/2018/10/1 ... thematica/
by stevend
Sat Oct 13, 2018 9:03 am
Forum: Raspberry Pi Desktop for PC and Mac
Topic: Issue with Pi desktop on compac Presario r3000
Replies: 5
Views: 1640

Re: Issue with Pi desktop on compac Presario r3000

Fully updated also - just redone it to be certain.
by stevend
Sun Oct 07, 2018 8:48 pm
Forum: Graphics, sound and multimedia
Topic: Dimming 200 Leds
Replies: 1
Views: 513

Re: Dimming 200 Leds

There are a number of ICs around which are designed to drive a number of individual LEDs, complete with brightness control. These have either an SPI or an I2C interface, both of which can be driven from the Pi. You'll need to use multiple ICs. SPI is potentially faster to complete an update, and, wi...
by stevend
Sat Oct 06, 2018 8:11 am
Forum: General discussion
Topic: Why sell a 7" screen?
Replies: 69
Views: 3090

Re: Why sell a 7" screen?

They're a good size for a control-panel type application - big enough to display a decent amount of information and have reasonable-size areas to touch, while not too big to be obtrusive. I have three of them round the house them to control my heating and other functions.
by stevend
Fri Sep 28, 2018 4:45 pm
Forum: Other projects
Topic: Lookign for some advise on best way to proceed - synchronisation/remote control
Replies: 5
Views: 805

Re: Lookign for some advise on best way to proceed - synchronisation/remote control

With UDP, there's no guarantee that the message is received. So I suggest you send a UDP broadcast to simply say that updated information is available, maybe with a version number. Any recipient of that broadcast then immediately triggers its polling cycle to get the updated information. Minimal cha...

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