homemade 868Mhz devices

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I know its not easy to connect existing 868mhz devices to pimatic?

But what about homemade devices like dht22, pir, ldr etc? Like the homeduino generic protocol.

Use 433mhz for switches and 868 for (homemade)sensors.

Is this possible?

Today I think we can use direct 2,4Ghz and real WLAN devices.
There exist more oss for that purpose.

2.4Ghz like mysensors is good, but WLAN will draw to much power for battery’s i think?

Yes. You are right with battery systems.
For this is 868MHz better

Yesss!!!

Most definately in favour!
I have been thinking about this already: maybe we shouldn’t reinvent the wheel. There are a few protocols flying around; like SWAP. We could implement that protocol to become very flexible in the hardware. RFM12B’s for bigger sensor nodes and for instance a Panstamp for the smaller sensors. A bit more expensive (€15,00) but it will run for more than two years on a single AA battery. And the Panstamp is able to encrypt info with AES256 for more sensitive parts of the house (security, NFC access cards).

And I want to throw in an option: synchronize sensors with the Pi. Give every sensor a fixed slot to send. I will open a seperate request for that after I thought it through a bit more.

But YESSSSSSSSSS!!

@DavidZH

Panstamp looks cool, but to expensive. I want something like

DHT22
PIR       >    ATTINY45/85     >     TX 868Mhz
LDR

Something like this guy has made: https://github.com/erniberni/temp_hum_raspi_rrd/blob/master/tinyTX_simple_receiver_mod.ino
But than integrated into the pimatic design.

@sweebee

Like I said: simple sensors with a ATTiny or arduino nano and RFM12B (€6 - €8).
I would want the Panstamp only when it will provide a service a RFM12B can’t. Like encryption or battery time.

I would like to exchange may Hama outoor weather sensor with a Panstamp because of “fire and forget”.
And I would like to implement one in energy monitoring. I don’t want that kind of date flying around the ether in plain text. Same with access-control.

All the other sensors around my house will be ATTiny/Nano based.

I will have to arrange a Panstamp on my Homeduino to be able to decrypt the messages from my energy monitor.

@sweebee said:

@DavidZH

Panstamp looks cool, but to expensive. I want something like

DHT22
PIR       >    ATTINY45/85     >     TX 868Mhz
LDR

I’m working on something similar but with 433mhz and the nano for development.
I have the ATTINY85 lying around…so I will probably come back to get this more battery friendly…

Would you mind uploading your code when you’re done, I never did any work on the attiny…

@georg90

this is my sketch for a pir only. The attiny normally sleeps but wakes when the input (pir) changes.

// ATMEL ATTINY 25/45/85 / ARDUINO
//
//                  +-\/-+
// Ain0 (D 5) PB5  1|o   |8  Vcc
// Ain3 (D 3) PB3  2|    |7  PB2 (D 2) Ain1
// Ain2 (D 4) PB4  3|    |6  PB1 (D 1) pwm1
//            GND  4|    |5  PB0 (D 0) pwm0
//                  +----+

#include <avr/sleep.h>
#include <avr/power.h>
#include <NewRemoteTransmitter.h>

const byte txPin = 3;  // pin 2          | 433Mhz zend pin
const byte inPin = 4; // pin 3 / PCINT4  | PIR pin

int address =   27951;  // KAKU adres

boolean input = false;
boolean state  = false;

NewRemoteTransmitter transmitter(address, txPin, 260, 3);

ISR (PCINT0_vect)
{
  // do something interesting here
}

void setup () {

  pinMode (txPin, OUTPUT);
  pinMode (inPin, INPUT);
  digitalWrite (inPin, HIGH);  // internal pull-up

  // pin change interrupt (example for D4)
  PCMSK  |= bit (PCINT4);  // want pin D4 / pin 3
  GIFR   |= bit (PCIF);    // clear any outstanding interrupts
  GIMSK  |= bit (PCIE);    // enable pin change interrupts

}

void loop () {

  input = digitalRead(inPin);   // read the input pin

  if(input == true && state == false) {
       transmitter.sendUnit(1, true);
       state = true;

     }

  if(input == false && state == true) {
       transmitter.sendUnit(1, false);
       state = false;
  }

  delay (10);
  goToSleep ();

}


void goToSleep () {

  set_sleep_mode(SLEEP_MODE_PWR_DOWN);
  ADCSRA = 0;            // turn off ADC
  power_all_disable ();  // power off ADC, Timer 0 and 1, serial interface
  sleep_enable();
  sleep_cpu();
  sleep_disable();
  power_all_enable();    // power everything back on

}

The only issue is that the pull-up resistor consumes power when you push the button or when te pir is active. The internal pull-up is around 35K? Don’t know if a 100K would work, but if so it should use less power.

I have almost the same code for my light switch. But that operates on 433MHz to keep it in the KaKu spec. like the code from Sweebee.
Now I am waiting for some RFM12’s to arrive. So I will report back after that.

First: let’s study the datasheet!

I think mysensors 2.4ghz is the best way for homemade sensors. So in my opinion this request is solved.

are support for 868MHZ Devices in planning?

i have now some 868MHZ devices and it would be nice, if
i can this with pimatic/homedruino. eg. smoke detector

there are already solutions for integrating homematic into pimatic like this plugin
https://forum.pimatic.org/topic/596/new-plugin-for-homegear

also this threat is interesting too
https://forum.pimatic.org/topic/459/are-there-any-plans-to-include-homematic-components-as-plugin/7

and there’s another plugin
https://github.com/dfischbach/pimatic-coc/