These ultrasonic sonar distance sensors are really common in robotics projects, but they can also be used for automation, interactive art, and motion sensing. They work at about 2 cm to 450 cm away, but we think 10 cm – 250 cm will get you the best results. Sensors look very similar and have a pair of flippers.

⚠️ THIS FEATURE IS NOT AVAILABLE IN THE CC2530/CC2531 ROUTER FIRMWARE

The US-100 is very similar to the popular HC-SR04 ultrasonic sensor and even looks the same, but it can work in the UART mode and provide more precise measurements. Compatible sensors are (there are many clones, but you can find examples of data packets below):

HY-SRF05, HC-SR04, HC-SR04 3-5V, US-100, HC-SR04P, US-015, US-016, HC-SR04+, US-026, IOE-SR05, RCWL-1601, AJ-SR04M:

These sensors return two bytes with a distance values:
0x12 0x34 (MSB LSB)
MSB – most significant byte.
LSB – less significant byte.

HRLV-MaxSonar series:

The sensor returns a value as ASCII characters:
R1234<CR>
<CR> – ASCII code 0x0D

JSN-sr04t, DYP-A01, A02YYUW:

These sensors return two bytes with a distance values:
0xFF MSB LSB CRC
0xFF – fixed header byte.
CRC – Checksum as a sum of all bytes before.

DFRobot URM06, URM07:

These sensors return two bytes with a distance values:
0x55 0xAA 0x11 0x02 0x02 MSB LSB CRC
0x55 0xAA – fixed header byte.
CRC – Checksum as a sum of all bytes before.

Zigbee firmware configuration for US100

It would be best if you used the jumper is on the board to select the UART mode.

Connections

P02 (UART RX) → Tx
P03 (UART TX) → Rx
GND → GND
3.3V → VCC
Do not forget about the jumper. If you do not receive data from this sensor, try to swap Rx and Tx wires.

Zigbee firmware configuration for HC-SR04 compatible sensors

This sensor requires a trigger signal to start a measurement, and the firmware uses the “I2C SCL” signal for it. It would be best if you defined it immediately after the HC-SR04 sensor.

Note: the firmware cannot measure a signal width with precision in microseconds. Therefore, the measured distance is rounded to about 15 centimeters. If you need better accuracy, use US100 instead.

Connections

I2C SCL → Trig
HC-SR04 → Echo
GND → GND
3.3V → VCC

Interval

If the value in the “Interval” field is not zero, the firmware executes measurement every N seconds. It sends a new value to a coordinator only if a distance value changes. But the firmware always sends the latest measured value with a periodic report.