PCB drope voltage

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amonares

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I'm working on a PCB that has a Teensy 3.5, a Raspberry, 2 IC 74HTC245, a photocell resistor, AM2302 temperature sensor, a tilt sensor among others resistors and capacitors.
The main goal is to read some sensors, display results on LED display, and pass the info to the raspberry to upload to a server.

The issue I assume is related to my PCB, I connect the Teensy to the PCB and there is a drop of voltage.

The Teensy is running the SmartMatrix Feture Demo, when the teensy is in "the air", the led work as expected. But when the Teensy is connected on the PCB, the LED turn off and for instance the output A8 PWM gives around 2.2V on the air, but when it's on the PCB the voltage drops to 1.65

Any advice will be appreciated.
Best regards from Chile
Álvaro Monares G.

In the air:
in_the_air.jpg

On the PCB
on_pcb.jpg

How will it be
Velocimetro-placa.jpg
 

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Solved, I have some Teensy pins without any function but sometimes touch the PCB because the holes are plated, so they were connected to ground.
The solution remove headers without any function.

Thanks anyway :)
 
A new example of problems from a 'floating pin'?

Interesting - I scanned the post and nothing came to mind with pictures and info given. What pins were the culprit?
 
good question, what is the default status of "non declared" pins in teensy? output?
I'm also working on a PCB for teensy I don't want to have the same issue
 
The undeclared pins should be High Z state.

Those traces are really small, your going to have voltage drop issues powering the LCD and Teensy possibly.
Possible bridge between a GND pin and something your using?
 
How I said, the issue was related to connecting to ground some pins without function.
female_heander.jpg
I use a female header soldered to PCB, i remove the unused and problem solved.

Best regards
 
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