Sr04 not working on nano lot 33

Other Hardware Sensors
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Hello, im trying to use a sr04 distance sensor with my nano iot 33, and it simply just outputs 0cm every time. I know that the sensor works and that the pins are in the correct placement because when I replaced the bot 33 with a normal nano and uploaded the code the sensor worked perfectly. I am just using the example sketch provided with sr04 library

Answer: thanks to the help, I've solved it. What you need to do is solder the two pads on the underside of iot 33 on the vusb and add 2 10k resisters in series from the echo pin to the pin you want to use for the echo so that it brings the 5v logic down to 2.5v.

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Maybe because the run-of-the-mill HC-SR04 should be fed 5v on the Vcc pin and you are giving it 3.3v? If used with a 3.3v microcontroller that does not have 5v-tolerant inputs (like yours), then the echo output needs to be level-shifted, such as by the simple approach mentioned here... using a voltage divider with two equal value resistors: HC-SR04 Ultrasonic Sonar Distance Sensor + 2 x 10K resistors : ID 3942 : $3.95 : Adafruit Industries, Unique & fun DIY electronics and kits

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Can't you use the VUSB pin for a 5v output on the iot 33?

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What does your voltmeter say?

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Nevermind im an idiot i figured out what you meant

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When I used the voltage divider method it still doesn't work, also I don't have a voltmeter

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If you are feeding 5v to the HC-SR04 and hadn't been using level shifting on the echo pin, you may have killed the Nano's pin. Maybe try another pin.

I don't have a Nano IOT 33, so I'm not sure about VUSB. What does the Nano IOT 33 datasheet say about using VUSB? I seem to remember seeing something about "no connection" unless a jumper is closed somewhere......

Also, in lieu of a voltmeter, you could try lighting an LED with VUSB (and current-limiting resistor).

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So apparently I have to solder two pads under the 5v pin for it to work, which is a relief that I haven't been damaging the board. Also thanks for your help! Ill solder it later and let you know how it goes

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Ok, hope it works. BTW, you really should get a digital multimeter, if you plan to do anything more than this project. Even a cheap one ($10 or $15) is better than nothing.

1 Like
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It works!

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:+1:

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