HC-SR04 Ultrasonic Distance Measurement Control Module

The HC-SR04 Ultrasonic Distance Measurement Control Module automates the use of the HC-SR04 Ultrasonic Range Finder and other ultrasonic modules and provides a direct readout of the distance as well as the measurement in centimeters over a serial port.

Key Features:

• Plug-in port for HC-SR04 Ultrasonic Range Finder module
• Also compatible with other ultrasonic modules as noted below.
• Built-in microcontroller automates distance measurement
• Built-in 3-digit display shows distance in centimeters
• 5V operation

This small module includes a built-in microcontroller and 3-digit LED display. Just plug the HC-SR04 Ultrasonic module into the female header and apply 5V and ground. The module will now display the distance in centimeters. The HC-SR04 is good for about 2 to 400cm detection distance which is about 1″ to 13 feet and the display updates the distance every second.

The module also sends the distance data out a serial pin in the format of ‘D:XXX‘ where XXX is the distance in centimeters. The data is sent every second at a baud rate of 9600 and this pin can be monitored by a serial port on an MCU if desired as shown in our example below.

The module has several uses. One is simply to easily test HC-SR04 Ultrasonic modules without having to wire them up to an MCU. Another is to provide a display of the distance data such as when using the HC-SR04 on a robotic vehicle and you want an easy way to monitor the distance that the HC-SR04 thinks it is seeing.

Use with Other Ultrasonic Modules:
The module has a 4-pin header designed for use with the HC-SR04, but it can be adapted for use with other ultrasonic modules that use the same basic ping interface including the US-100 and HY-SRF05.

US-100:

• To use with the US-100, remove the jumper on the US-100 module. This puts the module in the ping interface mode rather than serial mode.
• Insert the 5-pin US-100 header into the 4-pin female header so that the extra GND pin on the one end is left unconnected. Since the module has two GND pins it is not needed.

HY-SRF05:

• To use with the HY-SRF05, you need to remove the resistor R9 on the back of the HY-SRF05 module. This isolates the OUT pin which is not normally used.
• Short the OUT pin to the adjacent GND pin.
• insert the 5-pin HY-SRF05 header into the 4-pin female header so that the original GND pin is left unconnected. Ground is now supplied through the OUT pin which is now connected to the GND pin.

JSN-SR04T:

• This module is not compatible with the JSN-SR04T waterproof range finder. The JSN-SR04T requires a longer Trigger pulse of approximately 20uS and this module outputs a 14uS Trigger pulse that results in erroneous readings.

Module Connections:
There is a 4-pin female header on the assembly for plugging in the HC-SR04 ultrasonic sensor. The sensor is inserted so that it points away from the LED display.

Power and ground can be supplied via the 6-pin male header as shown below or by connecting to the 2-pin JST XH style connector on the board. Observe the polarity markings on the board if using the JST connector.

1 x 6 Male Header:

• VCC – Connect to 5V
• TX – Transmit Data. Connect to a serial RX pin on an MCU to monitor serial output
• RX – Receive Data. Not used
• DIO / NRST– No connection. Module pin may be marked with either name
• CLK / SWIM – No connection. Module pin may be marked with either name
• GND – Ground. This ground needs to be in common with MCU if one is used.

Evaluation Result:
These are pretty handy little modules that work quite well for their designed purpose.HC-SR04 Ultrasonic Distance Measurement Control Module – In Use with Uno

To get up and running only requires connecting power and ground, but the program below shows one method to monitor the serial output of the module so that an MCU can get the distance data and use it for making decisions. In our example, we are just checking for each character and passing it out the USB port so that it can be displayed in the Serial Monitor window to test the device.

In our example, we are using SoftwareSerial.h so that it will work with any Arduino style MCU. If the MCU has an extra hardware serial port, that can be used instead. The RX pin on the module is connected in our example, but it is not actually doing anything as the data is only flowing from the module to the MCU.

Once the program is downloaded, open the Serial Monitor window and ensure that the baud rate is set to 9600. It should be updated with the displayed reading every second which will look something like D:017 where 017 is 17 centimeters.

Package Includes:

1 x HC-SR04 Ultrasonic Distance Measurement Control Module