Friday, October 21, 2016

Gateway 1.7. ready

Here it is fully functional and ready. I'm happy man :)

This is actual look of new and fully assembled board, except expansion connector. I have components to build few of these and final price is around 70EUR ~ 75USD without antennas and pigtails. Buy it on the right panel in my online store.

Just to speak about component quality. I'm using only branded and original parts that are supposed to last. Like Japanese and Korean(better to write Korean then Samsung these days :), just a silly joke) capacitors. IC from TI, ST, WizNet and Maxim. Ports are isolated by TVS or optocouplers . There are ferrite beads where they need to be, not replaced by 0 Ohm resistor. Isolated MagJack for RJ45 and so on... With this I hope it will last for years.

It comes with latest OHS firmware loaded, as available on my GitHub account.

Friday, October 7, 2016

Connecting balanced PIR sensor.

Picture on right side shows how to connect balanced PIR sensor. The idea is beautifully simple, I'm not the author I have got inspired by professional alarm boards. It is required to add two resistors into the end of every PIR sensor loop, and create simple voltage divider. Any analogue input on gateway is prepared to handle such divider. Resistor values are set in software and expected value is 2k2 Ohm for both. As you see from diagram there only 3 wires needed to connect a PIR to gateway input as ground is common to both. There is possibility to daisy chain the sensors in one loop, but then you need 4 wires and the resistor divider will be present only on last sensor in chain.

With such setup the gateway is then able to recognise 3 different states of any sensor. That is OK, PIR and Tamper. And it is very hard to tamper the wires connected to sensor as attacker is not able to measure the resistance hidden inside the sensor.

Tuesday, October 4, 2016

Gateway 1.7. pre-order

Gateway PCB is in fabrication, and I'm hoping for the best that there will be no errors on PCB. It will have following parameters:
  • MCU ATmega1284P, 16KB RAM, 128KB Flash.
  • 8 analogue inputs for balanced PIR sensors.
  • 4 digital inputs for simple sensors, like door/window reed switches.
  • 1 box tamper input.
  • TWI/I2S expansion connector for up to 4 additional 8 channel analog inputs.
  • 2 relay outputs with selectable 12V power out.
  • RS485 protected interface for wired nodes.
  • RFM69HW for wireless nodes and sensors, pigtail and rubber antenna.
  • W5500 10/100Mbps Ethernet for web interface and MQTT.
  • SIM900 GSM modem for SMS alerting, pigtail and rubber antenna.
  • RTC clock with separate battery backup with NTP synchronization.
  • 512kb EEPROM as logger
  • Power Off and Empty battery inputs.
  • Standard FTDI Arduino programming interface.

I have been so bold that I put it on pre-order in the BUY section on right for 72EUR or 79USD.

Sunday, October 2, 2016

Fun with timers

Setting 4 timers on gateway web interface with double the start and stop time for each one. Then adding 4-channel relay board to node. And here is result, nice binary counter :)