Creating a USB-C Passthrough with power charging detection

[StealthRT]

Hey all I have a project I am needing to do but I'm unsure as to the best way to go about doing it.

What I am wanting to do is check to see if a tablet or laptop is plugged into the USB-c cable so that I can have a visual representation of confirmation that it is connected correctly.

Most of the tablets I am using do not have any visible feature that showcases that its plugged in or not. But even if it did i would never be able to see it due to the tablets being close together.

This is what my setup I created looks like:


When your placing the tablet/laptop into the slots from the front it's difficult to tell if it made it into the connector or missed it.

So my idea was to create a PCB that has 6 female USB-C inputs and 6 female USB-C outputs. But I am not sure what I need to test on the pins to determine if its connected to something or not? I plan on using an arduino to check the voltage and see if it drops XX amount when something is plugged in but again, there may be a better way of checking it?

My PCB would look similar to this one but without the headers and holes and with more than one set:

 

[transconductance]

You need to monitor the current, not a voltage. Put a small-value resistor, like 0.1 ohms, in series with the power. Measure the voltage across the resistor. Since you don't actually need to measure the current, just detect a threshold, you can use a comparator such as LM311. If you did want to measure the current, for example to detect end of charging, use a current sense amplifier such as an INA199 to gain-up the small voltage across the sense resistor to a level your Arduino ADC can easily measure.

 

[transconductance]

Note that the LM311 can easily drive an LED so you wouldn't need anything else, like an Arduino. Or, you can buy USB cables that have current/power indication built-in. Search Amazon for "usb c cable with display"