Cheap USB-C to micro USB Cables: Are they any good?

Stock photo of an USB adapter, from

The short answer is no. What could possibly go wrong when manufacturing a simple adapter cable that breaks out the USB 2.0 pins from a USB-C connector and makes them available on a micro USB? A lot, it seems. Even though this sub-$1 adapter cable features the right types of connectors, it simply does not work. Time to check what’s hidden inside.

USB-C to micro USB adapter cable
Manufacturer logo on the plug

Thankfully the connectors were molded using very soft material that could be cut open easily. With the shielding enclosures removed, we find a simple micro USB plug connected to a USB cable, which in turn has been soldered to a breakout board attached to the USB-C connector. All USB 2.0 signals on the USB-C plug are connected to the micro USB connector: GND (pins A1 and A12, bridged), Vbus (pins A4 and A9, bridged), D+ (pin A6) and D- (pin A7). So why doesn’t it work?

Micro USB connector
USB-C connector

Turns out, neither the cable nor the connectors feature any electrical components. However, USB-C requires a signal on the CC pin (pin A5) to identify whether an attached peripheral is going to source or sink current. With no resistors to pull the CC pins to GND, it is fairly obvious that chances of getting this to work are non-existent (unless the peripheral is self-powered, maybe?). Moreover, both CC pins are tied together on the PCB, rather than pulling them down individually. Rather than trying to fix this, and given the fact that I had already removed the strain relief on both ends, this cable has become useless for me.

USB-C breakout board pin alignment
USB-C breakout board (front view)
USB-C breakout board (reverse view)