Wednesday, June 19, 2024

Reference Design For An Automatic Liquid Dispenser

Reference design for a liquid dispenser that employs an infrared LED and a phototransistor to detect hand and dispense a predetermined amount of liquid.

Do you want to design your own liquid dispenser for your home or workplace, then this reference design from Renesas will simplify your job. The RL78/G11 from Renesas is a reference design for an automatic liquid dispenser that provides a hands-free solution for dispensing liquids such as soap, hand sanitiser, shampoos, or hand lotions. Designed to promote hygiene and reduce bacterial transmission, this dispenser is suitable for both public places and private institutions. By incorporating a touch-free design, the dispenser ensures that users do not need to touch any part of the nozzle, resulting in a more sanitary environment.

The dispenser operates based on motion activation. When a hand is detected near the nozzle, a microcontroller unit (MCU) triggers the pump motor, causing the dispenser to emit liquid. The amount of liquid dispensed per activation is carefully controlled to minimize waste. This feature helps conserve resources and ensures efficient use of the liquid being dispensed.

To detect the presence of a hand near the nozzle, the dispenser utilizes an infrared LED and a phototransistor. When a hand comes close to the nozzle, it interrupts the transfer of optics between the LED and the photo transistor. The MCU detects this change in status and subsequently activates the motor to dispense the liquid. This mechanism allows for precise and reliable operation of the dispenser.

The reference design incorporates the RL78/G11 low pin and internally configurable analog MCU. This MCU offers low-power consumption and fast wake-up times, thanks to its medium-speed on-chip oscillator. Additionally, the design includes the ISL9001A high-performance low dropout linear regulator for efficient power management. The regulator supports a wide input voltage range, from 2.3V to 6.5V, while featuring extremely low quiescent current. This helps extend the battery life of the dispenser, ensuring long-lasting operation. Overall, the Automatic Liquid Dispenser reference design provides a convenient, hygienic, and efficient solution for hands-free liquid dispensing. Its use of motion activation, precise liquid control, and power-efficient components make it an ideal choice for various applications in both public and private settings.

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Features of reference design include:

  • Dispenser distributes a set amount of liquid per motion activation to minimize waste
  • If hands are placed under the nozzle, an LED and buzzer are turned on to indicate liquid dispensing
  • Even if hands remain under the nozzle, liquid dispensing has a maximum duration of 2 seconds
  • When the battery voltage is lower than 4.8V, an LED blinks to indicate this low power condition when hands are placed under the nozzle.
  • Amount of liquid per motion activation: 0.5ml/0.8ml selectable

This reference design has been tested by Renesas. It comes with required design resources such as sample code, schematics, BoM, etc. You can find additional data about the reference design on the company’s website. To read more about this reference design click here.


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