# HC-SR04 Ultrasonic Sensor - rpi-srf - status not available

**URL:** <https://discourse.nodered.org/t/hc-sr04-ultrasonic-sensor-rpi-srf-status-not-available/21955>\
**Category:** General\
**Created:** [19 February 2020 03:19 UTC](https://discourse.nodered.org/t/hc-sr04-ultrasonic-sensor-rpi-srf-status-not-available/21955 "2020-02-19T03:19:47Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![cymplecy](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cymplecy/32/2773_2.png) [@cymplecy](https://discourse.nodered.org/u/cymplecy)\
**Post date:** [19 February 2020 13:03 UTC](https://discourse.nodered.org/t/hc-sr04-ultrasonic-sensor-rpi-srf-status-not-available/21955/6 "2020-02-19T13:03:24Z")

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The node works for me (trig connected to pin10 - echo to pin 8, gnd to pin6 , vcc to pin 1)

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/8/1/81a1992d97f7efcbea2c315ddee493cfeb27124a.jpeg)

There are a a few things to check

Have you got a newer 3.3V compatible version?

If using an old 5V version - you need to use some resistors to reduce the echo signal voltage

> **[Interfacing HC-SR04 Ultrasonic Sensor with Raspberry Pi](https://electrosome.com/hc-sr04-ultrasonic-sensor-raspberry-pi/)**
>
> In this tutorial we will learn about interfacing HC-SR04 Ultrasonic Distance Sensor with Raspberry Pi. Here we are using Python programming language.

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