Creating a USB-C Passthrough with power charging detection - Page 1
Forum section: electronics / projects

author: Stealthrt
author_rank: Regular Contributor
timestamp: April 19, 2023, 12:29:29 am
content: 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 pluggd into the USB-c cable so that I can have a visual repesentation 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: enter image description hereWhen 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: enter image description here

author: Algoma
author_rank: Frequent Contributor
timestamp: April 19, 2023, 02:41:57 am
content: There exists USB charger hubs with large quantity of ports and indicator lights for connection or charger status. I'm on mobile so can't find a specific link, but amazon has plenty to look at.

author: Stealthrt
author_rank: Regular Contributor
timestamp: April 19, 2023, 03:40:01 am
content: Thanks for the reply. I’ve looked on Amazon and got around $100 but I can get at best 3 usb-c ports with ~35watts/each. I just bought 6 45 watt wall chargers for each so I know it has enough power to charge. Plus that only cost me $60 for them all.

author: MrAl
author_rank: Super Contributor
timestamp: April 19, 2023, 11:47:15 am
content: Hi,You can use individual current monitors for each that would show voltage, current, ampere hours, etc.

author: Stealthrt
author_rank: Regular Contributor
timestamp: April 19, 2023, 01:12:01 pm
content: Have a URL to these that you are talking about?

author: devan
author_rank: Contributor
timestamp: April 20, 2023, 02:36:09 am
content: Not a perfect off-the-shelf solution, but you can buy USB-C cables with embedded 7-segment displays that show the rough amount of power being drawn. Since they only turn on the display when both ends are plugged in, you could use the display as an indication of whether it's plugged in all the way or not.I found it to be kind of handy when I went on a trip and spent a lot of time rotating between charging various phones and devices with only one fast charger since you can check if the device is charged without waking the screen by looking to see if the power draw is down to a watt or so.I bought this specific cable, but there are probably other random unpronounceable brand cables that are equivalent:https://www.amazon.com/Braided-Charging-Display-MacBook-Samsung/dp/B09HC4K3KP/ref=asc_df_B09HC4K3KP/

author: Stealthrt
author_rank: Regular Contributor
timestamp: April 20, 2023, 03:35:24 am
content: I was thinking about buying those type of cables before ultimately going with a normal USBC cable. The issue I am trying to solve is the fact that we don’t see the back end where they connect to. So having the screen on the connector would not help.I was thinking today that I could use a limit switch in each decider for the tablet/laptop to hit causing the signal that it’s charging but that doesn’t really tell me it’s connected correctly and is actually charging.

author: fchk
author_rank: Frequent Contributor
timestamp: April 20, 2023, 07:58:11 am
content: USB-C has got CC1 and CC2 signals on pins A5 and B5. These pins are used for device detection, plug orientation detection and host/device detection. A host has pullups, a device has pulldowns. Measure the voltage at these pins with an ADC, and you should be able to detect plug-ins and removals.fchk

author: Stealthrt
author_rank: Regular Contributor
timestamp: April 21, 2023, 12:14:56 pm
content: Quote from: fchk on April 20, 2023, 07:58:11 amThat sounds promising. Would you mind drawing up a quick schematic of this? I'm a visual learner

author: Stealthrt
author_rank: Regular Contributor
timestamp: April 23, 2023, 02:04:57 am
content: So something like this?