Detect changes in carbon monoxide concentration with the Household Gas Alarm featuring the Renesas RL78/G10 microcontroller and ISL28113 operational amplifier.


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.

Product Details

  • Minimum instruction execution time: Can be changed from high speed (0.05μs at 20MHz operation with high-speed on-chip oscillator) to low speed (1.0μs at 1MHz operation)
  • General-purpose registers: 8-bit register × 8
  • ROM: 1KB to 4KB, RAM: 128B to 512B
  • Selectable high-speed on-chip oscillator clock: 20/10/5/2.5/1.25 MHz (TYP.)
  • On-chip single power supply flash memory
  • On-chip debug function
  • On-chip selectable power-on-reset (SPOR) circuit
  • On-chip watchdog timer (operable with the dedicated low-speed on-chip oscillator)
  • On-chip key interrupt function: 6 key interrupt input pins
  • On-chip clock output/buzzer output controller
  • On-chip BCD (binary-coded decimal) correction circuit
  • I/O port: 8
  • Timer
    • 8/16-bit timer: 2 channels
  • Serial interface
    • CSI: 1 channel
    • UART: 1 channel
    • Simplified I2C communication: 1 channel
  • 8/10-bit resolution A/D converter: 4 channels
  • Standby function: HALT or STOP mode
  • Power supply voltage: VDD = 2.0V to 5.5V
  • Operating ambient temperature: TA = -40 °C to +85 °C
瑞萨电子展示采用 RL78/G10 微控制器的家用一氧化碳气体报警器快速解决方案。
瑞萨电子展示采用 RL78/G10 微控制器的家用一氧化碳气体报警器快速解决方案。
瑞萨电子展示采用 RL78/G10 微控制器的家用一氧化碳气体报警器快速解决方案。

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.