The Household Gas Alarm is a system that warns people with a flashing LED and buzzing alarm as soon as a change in carbon monoxide concentration is detected due to gas leakage or incomplete combustion. Home safety levels could be improved with this simple device.

This Household Gas Alarm reference design features the RL78/G10 low pin count, compact, low power general-purpose MCU which controls the LED and buzzer by using a buzzer output controller. The voltage value obtained by amplifying the output voltage of the carbon monoxide sensor with the ISL28113 operational amplifier ​​is converted by an A/D converter every second to acquire carbon monoxide concentration data. A buzzer will sound when it determines that a warning is required. In addition, with the STOP mode function of the RL78/G10, low power consumption control can be realized. The RL78/G10 is a small pin microcontroller best suited for consumer product miniaturization.

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Disclaimer: THIS MATERIAL IS PROVIDED “AS-IS” FOR EVALUATION PURPOSES ONLY. RENESAS ELECTRONICS CORPORATION AND ITS SUBSIDIARIES (collectively, “Renesas”) DISCLAIM ALL WARRANTIES, INCLUDING WITHOUT LIMITATION, FITNESS FOR A PARTICULAR PURPOSE AND MERCHANTABILITY. Renesas provides evaluation platforms and design proposals to help our customers to develop products. However, factors beyond Renesas' control, including without limitation, component variations, temperature changes and PCB layout, could significantly affect the product performance. It is the user’s responsibility to verify the actual circuit performance.


  • Demo board includes the RL78/G10 MCU
  • CO concentration detection cycle is 5s, and the status indication cycle is 20s
  • If the CO concentration and its duration time achieve the alarm threshold values, the audible and visual alarm will occur
  • The green LED blinks every 20s, to indicate that the system is running
  • If the battery voltage is lower than 3.6V, a low voltage alarm will occur
  • Should the system crash or the program is out of control, it can restore itself automatically



Type Title Date
Datasheet PDF 398 KB
Brochure PDF 12.02 MB 日本語
Datasheet PDF 1.65 MB
3 items

Design & Development

Sample Code

Household Carbon Monoxide Gas Alarm

Renesas demonstrates the Household Carbon Monoxide Gas Alarm quick solution featuring the RL78/G10 microcontroller. This solution is designed to protect people's lives and property from carbon monoxide build-up inside a house or building.