PM2.5 Monitor with Portable Battery

Renesas has created a reference design for the PM2.5 monitor, which is a portable device that can measure and detect the concentration of atmospheric particulate matter (PM). Utilizing an LCD to display the density of particulate matter, the PM2.5 monitor also has LEDs to show air quality and battery capacity.

With the use of the RL78/L12 microcontroller, this design features low power consumption and a compact LCD MCU which includes functions such as I/O port, STOP mode, A/D converter, buzzer, LCD controller, and more. Paired with the Intersil ISL97656 DC/DC converter IC, this combination offers controlled battery discharge. Adding Intersil's ISL6294 battery charger IC also helps control charging.

Features

• Minimum instruction execution time can be changed from high speed (0.04167 µs at 24 MHz operation with a high-speed on-chip oscillator) to ultra-low speed (30.5 µs at 32.768 kHz operation with a subsystem clock)
• General-purpose registers: (8-bit register x 8) x 4 banks
• Selectable high-speed on-chip oscillator clock: 24 MHz /16 MHz /12 MHz /8 MHz /6 MHz /4 MHz /3 MHz /2 MHz /1 MHz (typical)
• On-chip single power supply Flash memory
• On-chip debug function
• On-chip power-on reset (PoR) circuit
• On-chip watchdog timer (operable with the dedicated low-speed on-chip oscillator)
• On-chip clock output/buzzer output controller
• On-chip BCD (binary-coded decimal) correction circuit
• I/O port: 20 to 47 (N-ch open drain I/O [EVDD with stand voltage]: 2)
• Serial interface
• CSI: two channels
• UART: one channel
• Simplified I²C communication: one channel
• Standby functions: HALT mode, STOP mode, SNOOZE mode