Ultrasonic UART Adapter

Figure 1 Ultrasonic UART Adapter

Using common ultrasonic sensors such as the popular HC-SR04 with a microcontroller maybe not that complex when used in simple applications. However, many real world projects will come with complexities of its own that makes the integration of ultrasonic sensors challenging. Traditionally, microcontrollers would have to poll on return signals of ultrasonic sensors to be able to calculate distance. This can be an issue in software as this receive sequence and actual transmission may be blocking algorithms. Using timer interrupts also incur processor time overhead and added reading error. Using pin interrupts is also a common implementation but may not be as simple as other methods. Servicing the ultrasonic reading sequence is also timing critical. Finally, the issues multiply quickly as more ultrasonic sensors are integrated into a single microcontroller.

The UltraSonic UART  (USU) adapter attempts to minimize all of these issues and includes other value added features useful for both microcontroller and non-microcontroller based projects. The USU includes an HC-SR04 module installed on a header within the PCB. The onboard processor takes care of all the reading, processing and presentation of distance information. All of the ultrasonic related functions are therefore off-loaded into the internal processor, freeing the external host microcontroller to perform other important tasks.

The distance readings are displayed on an onboard seven-segment digits and may be read by the host microcontroller by either hardware/software serial port (UART), by ADC using the analog output signal or by the digital output pin that changes state with the threshold distance set by the internal potentiometer.


  • Onboard processor simplifies integration of  ultrasonic sensor(s) in a system
  • Builtin Seven-Segment readily displays distance in centimeters
  • Multiple interface ports: Serial(UART), Analog Output, and Digital Output
  • Analog and Digital outputs only require one GPIO from host microcontroller
  • 5V logic level and power
  • Low power consumption
  • Maximum Current Consumption: 50mA
  • Typical Current Consumption: 20mA
  • Replaceable/removeable HC-SR04