USB-C Plugs, Sockets, and 5V supply

Assuming you want to use a USB Type-C connector, but just want USB2 (D-/D+) and 5V power.

So many get this wrong, however, it seems the answer is quite simple.

It would seem there are a number of connectors you can get, with just the main USB2 pins, or with all USB-C pins.

For a USB-C Socket, you need to connect CC1, and CC2, separately, via 5k1 resistors to GND. Like so.

However, for a USB-C plug, the CC1/CC2 pins are actually CC and VCONN. You connect CC via 5k1 to GND, and leave VCONN unconnected. If you connect both then it won't work! Like so.

Yes, the connector is reversible, so actually it does not matter if A5 or B5 are connected to the 5k1 resistor, just as long as only one of them is.

USB-C not so easy

Using a USB-C connector for power only is, sadly, not as simple as I thought.

Yes, the pins are tiny, butt the end pins are double pins on the connector and just about solderable (0.6mm wide for two pins together).

However, whilst this works when you use a legacy cable from a USB-A, giving 5V, this will not work to a true USB-C power supply or device.

Why?

Well, resistance is not futile, it seems. There are two connectors (CC1 and CC2) on the USB-C which need resistors to GND to tell the other end you want power.

Whilst the end power connections are two pins at a time (0.6mm), the CC1/2 pins are not, and are 0.3mm wide at 0.5mm spacing. That is pretty much impossible to mill, as the milled track is anything from 0.3mm to 0.6mm wide. The picture above shows around 0.5mm milled track, which is deliberately spaced to allow soldering to the pin 6th from the right. So double pin on right (GND), next double pin in (VBUS) and then another pin we don't care for and then the CC pin. Same on the other side of the connector, except the CC pin is next to the VBUS on that side.

Yes, it is possible to solder!

Then to add the 5.1kΩ resistors to GND.

The end result is power from USB-C...

P.S. Thanks to John for pointing this out to me.
P.P.S. John also pointed out that you do need the two resistors - and cannot simply common up CC1/CC2 with one resistor (as RasPi4 did, by mistake).

Powering widgets

Making widgets for the alarm system means that power is quite simple - the alarm wiring has 12V DC, and a simple regulator means I can connect to that - typically with screw terminals.

However, making other widgets with an ESP32, like the environmental monitor, or the Brexit clock, means finding a way to power them. I am not yet playing with battery powered stuff (will do, eventually), so need a power lead.

So what to use?

Initially I tried a micro-USB. Leads for this are very common, and USB-A sockets providing 5V are so common they are fitted to standard power sockets even, so seems ideal.

The issue is the connectors. I have struggled to find what I need. I did see some from China (which have not yet arrived) which have only the power tabs on them making soldering easier, and have clips to hold to the PCB. Whilst waiting for those, I tried some simple surface mount connectors.

The problem is they are not very robust, even superglued to the board, they can become detached very quickly.

I have actually made a set of tools under OpenSCAD two make tight fitting 3D cases to help hold the connector in place, which has helped, but that is still a challenge, and I am not happy about it.

The other catch is the tiny tiny surface mount connectors... Thankfully I only need the ones at the ends. For reference, the three pins at the bottom are 0.1" spaced.

So, I wanted to find a solution, and turned to USB-C. These are a nightmare, not only tiny tiny tiny surface mount tabs, but tabs under the connector so you cannot get to them with a soldering iron. Finally I found a part that will do, and from a UK supplier.

It did mean some fine milling, and even finer soldering, but again, only needing the double connectors at the ends, so just about possible. Those pads are 0.5mm spaced!

The result is a nice solid, soldered to the board, connector.