OHS is open Arduino based burglar alarm and automation platform. It can work as new alarm gateway, or it can replace your old alarm panel. OHS can use any wired 12V sensor, PIR, smoke or reed switch. It has Web interface that is used to set it up. OHS has GSM modem that is able to send SMS or page you. It has radio interface for environmental sensors. OHS is self-contained, it does not need any cloud service, only optional SMTP server for emails, or MQTT to publish collected sensor data.

Gateway board consists of ATmega1284P that has inputs for sensors and outputs to relays. It also hosts Wiz5500 Ethernet for configuration and overview, RFM69HW for radio remote nodes, communication module to wired nodes (RS485 protocol), GSM modem, Battery backed up RTC, EEPROM for log, I2C expansion connector, and AC supply and battery monitoring.

Gateway board has 8 analogue/balanced inputs that can recognize different events on PIR sensors, and 5 digital inputs. Inputs can be further expended.

Remote nodes act as authentication units or sensors. Currently they are set to receive iButtons as keys to arm/disarm the system.

• Hackaday link.
• Demo video of web interface.
• Demo video of authentification unit.
• Blog link.

Main gateway board:

• MCU ATmega1284P, 16KB RAM, 128KB Flash.
• 8 analog 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.
• W5500 10/100Mbps Ethernet for web interface and MQTT.
• SIM800C GSM modem for SMS alerting.
• RTC clock with separate battery backup with NTP synchronization.
• 512kb EEPROM as logger(4096 entries).
• Power Off and Empty battery inputs.
• Standard FTDI Arduino programming interface.