Sensor will not work with 3.3 volt input supply, only with 5.0 volts.
Hello.
I moved your post to our sensors support category since it is a better setting for troubleshooting.
Can you post some pictures of your setup that show all of your connections and explain more about how you are powering and reading the sensor?
- Patrick
I’m using the Arduino IDE with serial monitor. Power is supplied from my PC via USB with 5.1 volts going to the Moteino R4. The sensor works as expected while it is powered from the VIN pin of the Moteino, which is 5.1 volts and the red LED changes intensity as measured distance changes. If I power the sensor from the Moteino on board 3.3 volt regulator (pin of the Moteino next to VIN) it does nothing and red LED stays off. The sensor output pin is connected to D6 of the Moteino which is PWM. I get the same results from two of the Pololu 4079 sensors.
Can you try measuring the voltage across the sensor’s VIN and GND pins to confirm that it is actually receiving power?
- Patrick
Yes, the sensor VIN and GND measures 3.29 VDC
We have tested that board with voltages as low as 3V, and we are not really sure how it could fail in a way that lets it work at 5V but not at 3.3V. That makes it especially strange that you are seeing this behavior from two units. Can you try measuring the on-board regulator voltage when the board is powered from both 5V and 3.3V? You can do that by touching one of these points with your positive multimeter lead and GND with the negative lead.
If you have an oscilloscope, could you use that to look at what is going as well? Specifically, please check for unusual noise or transients on the supply voltage and the regulator voltage.
Also, I suggest making sure your GND wire is seated securely in the breadboard. In your picture it looks like the it might not be making good contact (though it might just be a long pin instead).
- Patrick
I switched to a new breadboard and new jumpers.
With an input voltage of 5.10, the measured voltage on the test point you identified is 2.86.
With an input voltage of 3.29, the measured voltage on the test point you identified is 0.16.
I don’t currently have access to an oscilloscope.
Short of a defective regulator, I’m at a loss for why I’m seeing this behavior.
I truly do appreciate you working to resolve this issue.
Scott
It is starting to appear like there might be something wrong with the regulator on your board. Can you email us at support@pololu.com with your order information and a reference to this thread? Also, can you let us know if you got the same results with both boards?
- Patrick
I do get the same results from both of the sensors. I actually purchased 3 of the 4079 sensors when they were introduced. I just connected the 3rd one and I get same results as the other two. All three produce the same distance reading when connected to 5 volt supply and are quite accurate. I really like these sensors, just need them to operate at 3.3 volts.
I will contact support as suggested.
Thank you Patrick
Scott
I am having the same problem with item #4052 (distance sensor 10cm): Only works with 5V, not 3V3.
Any conclusions for this issue ?
Thanks
Sorry, no additional information to share. For me, it only works with 5V applied.
Hello, @ALCastro.
I went my over the emails with schoskin from when we were troubleshooting this in 2021. We found that his results seemed to be caused by a strange interaction between the sensors and the controller he was using, but we were not able to conclusively identify the issue.
Can you post more information about your setup (like how you are powering and reading the sensor) along with some pictures showing all of your connections and close-ups of the board? Can you also try measuring the on-board regulator voltage and looking at your setup with an oscilloscope as suggested in this earlier post in the thread?
- Patrick
I know it’s been several years since the original post. After seeing the post from @ALCastro, I pulled my sensors out and tested again. It turns out that there is some unusual issue with the regulator on the Moteino I had been using, even though the measured voltage was 3.29 VDC. I connected to another Moteino, and all is well. Sorry for any confusion on this issue and thanks for your support.
1 Like
Many thanks for your replies, they gave me some enlights how to proceed.
My problem is similar (3V3 versus 5V) but the distance sensor is #4052 (10cm).
I will return to this forum, once I make some some tests.
Here are my findings:
A)
Powering with 3.27V
Voltage diferential A-B = 0.18V
Sensor does not detect any object (red LED does not light)
B)
Powering with 4.64V
Voltage diferential A-B = 02.80V
Sensor does detect object (red LED turns on)
Signal at OUT terminal is 4.3V
I decided to power the #4502 sensor with 5V and use a Logic Level Converter .
Thanks for your support.
What are the actual voltages you are reading at each of the points you circled? (i.e. please provide the actual voltage measurements relative to the board’s square GND pin, not the difference between them.)
The pad circled by A and the pads circled in group B are connected to the same net of copper in the PCB, so barring some physical damage to the PCB, it seems very unlikely that there would be significant voltage differences between them. Can you post some close up pictures of your boards as well as pictures showing how you are probing those points?
Also, what specific power supply are you using to power the board in your 3.3V case and your 5V case?
- Patrick