GPIO Input Pins - Connecting external devices with higher power requirements

[modernpachinko]

Hello!

I'm new to experimenting with GPIO on the PI. I'm trying to connect pins as GPIO inputs that collect statistics off this external device. In the service manual for this external device, it says the following about this pin out:

Maximum rated voltage: DC50V
Maximum rated current: 100 mA

While being new to GPIO, it does seem obvious that if I attempted to hook this up to the Pi I would damage it. My question is "what do I need to design between the external device and Pi to safely connect it?".

All wisdom shared is appreciated. Thank you for the assistance!

[DougieLawson]

It's impossible to answer without more details of what your device is and what it does.

[rpdom]

While being new to GPIO, it does seem obvious that if I attempted to hook this up to the Pi I would damage it.

It's not obvious at all.

That sounds like it may be the maximum ratings of a relay (either mechanical or solid-state), in which case it would be perfectly safe to connect it to a GPIO input with a couple of resistors.

As Dougie says, a bit more information about the device and how it connects would be helpful.

[modernpachinko]

Thank you for the thoughts so far. I attempted to originally post a few images, but even 400kb appears to be too large to attach, so my apologies for adding external links (OneDrive).

This is for a Japanese Pachinko Machine. They all contain a board with about 10-12 wire pairs that hook up very similar to connecting a wire to a speaker. Here's a picture of what that looks like.

https://modernpachinko-my.sharepoint.co ... A?e=WhH6Ej

The service manual indicates that each pair of wires that reports on the individual sensors has a maximum rated voltage of DC50V and maximum rated current of 100mA. It is a digital signal that will flip on for .060 seconds when the sensor is activated. I've attached that for reference as well below:

https://modernpachinko-my.sharepoint.co ... g?e=BZv4kh

In terms of how to connect to the PI, I'm trying to figure that out. Guessing one would go to a ground pin and the other to an available GPIO pin configured as an input. But given the ratings of each of these wire pairs, it seems something needs to go in between.

Please let me know if any additional context is needed.

Thank you for the help and have a happy holiday!

[davidcoton]

Connect the relay output one side to GND, the other to a 1K resistor. Other end of resistor to your chosen GPIO input.
In your program, configure that GPIO as an input with pull-up.

The resistor keeps the Pi safe even if the GPIO accidentally becomes an output with high level while the relay is closed.
It has no function while the GPIO is an input.

[boyoh]

My advice is when interfacing between different
Current levels is to use opto Isolator buffer stages
No common connection needed, and good noise
Isolation This method can be used both ways,
The opto transistor can switch power transistors
And solid state relays, Use common sense when
Working with different voltage and current levels
If you tell the forum more about your project
You will get more advice,

Regards BoyOh