New Zealand wall switches
After an exhaustive search I have failed to find suitable wall switches to fit the wall boxes in my home. I am not going to butcher my finished concrete walls to take 68 square euro boxes, so have decided to make my own. I do not have mains wiring in the walls, just a twisted pair plus ELV pair. I have decided to use modbus as the serial prootocol. If anyone else is interested in having some Aussie / New Zeland sized wall switches at a sensible price, now would be a good time to let me know. I am creating three, four and six illuminated button versions, and including temperature measurement and annunciator. I am open to the configuration of status register ideas all suggestions welcome.
I am not interested in radio frequency switches (far too much steel and concrete to work reliably, even 5GHz WiFi really struggles here) and not interested in telling China which switch is on today, hence a hard wired local solution. Power is 12 Volt and expected consumption about 20mA at idle.
Hi Hamish,
Yup. I have one right behind me. I cannot install them yet as I have commercial I/O boxes already installed which will not go faster than 9600 baud, so polling forty or fifty switches will not be possible on a frequent basis. Sooo… now I’m designing an I/O box that will run at 56 or 115kb.
I have made maybe twenty switches (prototypes) and produced ten front-plates.
They look o.k. Here’s a rundown on what the switch does-
There are 76 x 16 bit registers (yes, I know, but…)
Of these, the most important one is a status register.
This tells you if any button has been pushed since the last successful read.
so one just reads this and then moves on to the next switch if nothings happening.
Keeping the Modbus traffic to a minimum is paramount.
Now the front plate has six buttons (max) each button can be illuminated red or green.
The level of illumination can be adjusted in 0.1% steps so you’re not blinded by the bedside ones. My thinking is if you press a button it lights red then you’re responsible for turning it off again, if HA lights the controlled light the button lights green You can choose to ignore it as HA will look after it, or take control as you wish. The button presses are de-bounced and stored until they are read. The length of time the finger is on the button is recorded and available in 20ms intervals. (so you can do long press determination) The switch also has two button rollover. The switch also measures the temperature of the front-plate so one can use it as a thermostat. It also reports the CPU temperature, Input power D.C. voltage (in 1/10th Volt steps) so I can monitor the power distribution in my network along the line.
Also the CPU voltage (3.2V) is updated often.
It also has a terminal on the back to measure an external voltage (0…25V in 1/10ths) so I can use it to monitor a battery or two and also use it to capture a nearby door switch.
It also has a 64Mbit flash memory where I store spoken words that can be played through the on-board audio amplifier and tiny loudspeaker. So it can tell you there’s someone at the front door. I needed this 'cos I built my house and it’s sound proof. If the smoke alarm goes off downstairs I cannot hear it upstairs, so soon, my switches (all of them) will tell me fire, fire, fire and name the room where the alarm came from. It knows a couple of hundred words now but there’s room for some more. One can string together words with or without intervals. When you power it up, if you hold down two keys in the first minute it will speak the baud rate parity stop-bits modbus address etc. Some settings are protected by a password to prevent inadvertent writes. Fitting an external link puts it in a test mode at 9600 baud without changing stored setting to suit my test jig, stored setting are restored with a power up. So a network power down will not change the product settings. Full JTAG and debug connections are provided too. The switch counts it’s up-time in seconds, good and bad transactions, etc so you see how we end up with 76 registers!
Two voltage regulators, a 32bit Arm processor running at 48MHz consume just 25mA from a 12V D.C. power input. Pretty much full modbus compatibility with error reporting. It has a unique 64 bit serial number (4 registers) That’s about as far as I’ve got at the moment.
Let me know if you’re interested.
Hi, I am interested in NZ standard switch plates. I built my house 30 years ago and only have cat 3 or 5 cables in the light switches. No mains. I made my own switch plates, just simple push button switches and LEDs linked back to a central DI/O board. Works will for most applications but is limited in functionality.