TMP36 VOUT misbehaves when Arduino is powered by VIN

Other Hardware Sensors
1

Hi so like the title says, when I supply power to my Arduino UNO WIFI REV 2 with anything but the USB-Type B input, the output of the TMP36 sensor drops at room temperature from about 750mV to jumping values between 541mV to 590mV.

In this image is how everything is connected.

Screenshot from 2023-03-21 13-34-37
Screenshot from 2023-03-21 13-34-371054×822 187 KB

What I have is a heating element connected to this PWM controlled driver from amazon . I am powering the Arduino and the heating element with a 12V USB Type-C power bank where I am using a USB Type-C PD trigger board to supply power to the components.

However, when I supply power to the Arduino using VIN and GND from the Battery the TMP36 sensor does not provide accurate readings and the values jump. If I remove the VIN and GND from the battery to the Arduino and instead power it via the USB Type-B port the sensor works without a problem. The same issue happens if I use the round 5.5mm x 2.1mm jack.

What can be causing this strange issue? Thank you in advance for any help you can provide!

2

If you are using a 9V battery like this.

600×600 44.9 KB

Expect short run times and many issues involving low power.

3

What is the red pcb with the 4 wires connected to it?

4

The battery I am using is this Power Bank and to get positive and negative terminals out of it I am using this PD trigger board. I only showed the 9V battery to show the connections. But you still think that's the issue?

5

The red PCB is mimicking how I connected this PWM driver that I purchased. The connections look pretty similar.

Edit:

Here is an image of how to connect it by the manufacturer

61uiYN6pYhL.AC_SL1000
61uiYN6pYhL.AC_SL10001000×837 64.8 KB

6

You show TWO ground (GND) connections but there is only one

7

I don't understand. I have the following connected to GND on the Arduino:

  • DC- of the driver board
  • Negative battery terminal
  • GND pin of TMP36

Edit:

Sorry, forgot that GND of the driver board is also connected to GND on the Arduino.

8

Post a schematic.

Post an image of the project.

As a note. Most LiPo chargers require a certain amount of current drain to remain powered.

1 Like
9

I did post an image of the project in the initial post, are you not able to see it?

10

That should NOT be connected to the Arduino ground but that is not your problem.
As @Idahowalker pointed out unless it's an industrial enegizer 9V it will not last long.
You battery is probably almost dead.

11

Ok I disconnected DC- from the driver board to the Arduino GND but as you predicted that is not the problem since I am still measuring the incorrect VOUT from the TMP36 sensor. The battery currently has an 82% charge and it's brand new.

12

Can you take a photo of your project and post the actual project photo?

Image from post#1 looks like a Fritznuts diagram.

Problem, bread board power rail split:

1563×565 110 KB

Solution, bread board power rail split:

4033×1611 578 KB

13

Yeah absolutely, here is an image of the project.

PXL_20230321_190103975
PXL_20230321_1901039751920×1440 429 KB

14

When using the alternate power connections, not Vin, is 12V being used as a supply?

12V is the limit of the Uno's power converter. The Uno will be taking 12V and converting it to 5V. The converter will take 2.5ish for its self and blow the rest into the air as heat. It's that heat that may become a issue.

15

Yes, the connection that does work correctly is when I connect both USB Type-C from the power bank to the driver, and USB Type-B from the same 12V power bank to the Arduino.

16

How did you measure the charge level?
Once it drops below about 7V when connected to the UNO WiFi it won't power the board.

17

The power bank shows a percentage. I just measured it and its outputting 11.46V at 81%.

Here in this first image is the VOUT of the TMP sensor when using USB Type-B to power the Arduino from the same source:

PXL_20230321_192820475
PXL_20230321_1928204751920×2560 453 KB

In this second image, VOUT drops and changes almost every half a second. Here is using VIN instead.

PXL_20230321_192913867
PXL_20230321_1929138671920×2560 421 KB

18

0.754VDC is to supply what?

0.444VDC is to supply what?

Why put the Uno on a synthetic jacket that can develop a static charge? The wooden table top would be better.

19

Those DC measurements are coming from VOUT of the TMP36 sensor to the A0 pin of the UNO. And yes you are right, the table is better.

20

reads like a reset is occurring. I'd have to have the board in my hands to troubleshoot further.

1 Like