Features:

• 23 to 600 cm (9″ to 20 feet) detection range
• 40 kHz operation
• ±37.5 degree field of view
• 2.5 meter (8′) transducer cable
• 3.3 & 5V operation and logic compatible (see notes below about 3.3V operation)

The JSN-SR04T is very similar to the standard ultrasonic modules like the HC-SR04 with the exception that it uses a single waterproof transducer instead of two and it also provides more methods for interfacing to a microcontroller.

Because the transducer is waterproof, it can be used for indoor or outdoor sensing such as providing a car parking sensor, security alarm, obstacle avoidance or monitoring the water level is water storage tanks.

Operating Modes:

The module can operate in 6 different modes of operation using either the Ping or Serial mode of operation. These are set by shorting the M1 or M2 pads or placing a resistor of a certain value across the MODE pads.  The resistor value sets an analog voltage that is read by an ADC, so the exact value isn’t overly critical.

Mode 0 and Mode 2 are the most commonly used modes.

MODE 0: Ping Mode

Mode 0 is the default mode when there is no resistor on the MODE pads and neither M1 or M2 pads are shorted and is how the module is shipped.

In this mode, the module operates very similarly to the HC-SR04 and similar ultrasonic range finder modules and sample code for those modules can be used with this module with one exception. With the HC-SR04, the trigger pin is held high for 10uS. With the JSN-SR04T, the trigger pin must be held high longer – usually about 20uS for reliable operation.  The first test program below uses this mode.

MODE 1 - Automatic Serial Mode: To enter Mode 1, the M1 pads are shorted OR a resistor value of 47K is placed across the MODE pads.

In this mode the module continuously takes measurements approximately every 100mS and outputs the distance on the TX pin at 9600 baud where it can be read using a serial RX pin on an MCU.

MODE 2 - MCU Controlled Serial Mode: To enter Mode 2, the M2 pads are shorted OR a resistor value of 120K is placed across the MODE pads.

This mode is the same as Mode 1 except that the module takes a measurement only when a trigger command of 0x55 is sent to the RX pin on the module. The module then takes a single measurement and outputs the distance on its TX pin.

The minimum trigger cycle time is 60mS

MODE 3 - Automatic Ping mode: To enter Mode 3, a resistor value of 200K is placed across the MODE pads.

Mode 3 is similar to Mode 0 (ping mode) except that it automatically generates the ping every 200mS and outputs a pulse width high level corresponding to the distance.

MODE 4 - Low power Ping mode : To enter Mode 4, a resistor value of 360K is placed across the MODE pads.

This mode is the same as Mode 0 except that the module is set to low power in between Pings with a stated current consumption of < 70uA.

MODE 5 - Threshold Switch Output: To enter Mode 5, a resistor value of 470K is placed across the MODE pads.

In this mode, the module automatically takes a reading every 200mS and checks the measurement against a factory default threshold setting of 1.5 meters. If the detected distance is less than 1.5 meters, the Echo pin is set to HIGH. If the detected distance is greater than 1.5m, the Echo pin is set to LOW.  This can be handy for using the output to directly control something like a relay or LED.

Module Wring:

There is a 4-pin header on the assembly.

• 5V: Connect to 5V
• RX / TRIG: Connect to any digital output pin on MCU.  A 20uSec or wider pulse starts a measurement cycle in Ping mode of operation.  Alternatively it serves as the serial RX (receive) pin.
• TX / ECHO: Connect to any digital input pin on MCU.  This pin is held high for the duration of the the measurement cycle.  Alternatively it serves as the serial TX (transmit) pin.
• GND

Package Includes:

• JSN-SR04T V3.0 Electronic Control Module
• Waterproof Transducer with 2.5 Meter Cable