a Compact, cheap gas sensor with RS-485 connectivity

24V supplied, Gas detector with half-duplex RS-485 interface. For industrial application ready product, containing a current or voltage output for reference measurment. a sinlge LED used for showing cominucation or Error state. the small footprint makes it ready for most plastic enclosures. the PCB can be hand-solderd with a bit of skill. Use cases can be in Garage systems (linked with the vents and gas alarm system), hobbyist workshop or any other room such as Office spaces and schools.

The core is a MiCS-6814 Gas sensor. It was chosen due to the small build size, cheap price and containing a reduction (CO), Ox (zb. NO2) and NH3 sensor in one case. A STM8S003F3P is the logical unit. Is is cheap and readily available. Internally all components used are 5V supplied, by an oversized non isolated DC/DC converter. All PCB components can be sourced by Mounser.

Hardware is developed in KiCad 7.0. Initially i wanted to programm on STM Cube IDE. currently not shure if it will work on a 8bit microcontroller.

finished first version of scematic and layout

• clean up scematic
• simulate PWM to analog DC and check some datasheets
• test components and connectivity using breakout boards