USB Adapter for Intel Bluetooth/Wifi M.2 Cards

bluekitchen / 1st August 2024

USB Adapter for Intel Bluetooth/Wifi M.2 Cards

Bluetooth SIG added support for the Intel BE200 Bluetooth/Wifi card to their Profile Tuning Suite (PTS). The BE200 is a new Bluetooth Dual-Mode Controller that allows to perform all PTS tests including the ones for LE Audio.

The card itself is easily available from regular distributors like Mouser or Digikey. However, it only provides the Bluetooth USB functionality over its M.2 connector with Key E. While some computers with M.2 interface exist, for most you’ll need an adapter to plug it into your Windows machine. Bluetooth SIG refers to a company that sells the card together with a suitable adapter to connect it via regular USB.

As the shipping cost is rather high, and we already have some experience with Intel M.2 Bluetooth/Wifi cards, we describe two other options to use these cards here.

The Plug-Plug-and-Play Version

A few years ago, we helped a customer to use the Intel Wireless 8265 cards with our stack in the rugged laptop they chose for their field service people. To implement the firmware upload mechanism, we wanted to have the card available via regular USB on our Macs and started searching the Internet. After some initial trouble finding a suitable adapter, we ended up with a combination of: – A M.2 with Key E adapter to Mini PCIe and a – A Mini PCI-E to USB Adapter which worked rather well.

This plug-plug-and-play solution works also with the Intel BE200 card in PTS.

The Soldering Option

While browsing AliExpress for the Intel BE200, we also found a desktop wireless adapter version for PCI Express. It has the USB connection (4 pin cable) on the side, which is intended to be plugged into a motherboard USB connector. This probably works with a desktop computer, but we don’t have desktop PCs anymore.

So an idea came up: we just replace the motherboard USB connector with a USB-A plug and are done. However, after receiving the adapter and replacing the USB connector, it didn’t work. The manual doesn’t show the USB 5V line being connected at all and a bit of critical thinking revealed that there’s no reason that this adapter would have a voltage regulator from the USB 5V power supply to the internal 3.3V needed for the BE200 as it’s plugged into PCI Express, which already provides 3.3V.

We then added a 5V-to-3.3V converter and verified that it also works as expected. If you’re interested, here are the steps we took for this.

1. Remove heat sink

2. Add 3.3V Switching Regulator

Here, we used what was on hand, this DC-to-DC buck converter to 3.3V

We connected GND from the connector to Vin-, and 5V power from the connector to Vin+ as well as the EN input. Ideally, we would provide the 3.3V to the pin on the PCI interface, but had no suitable connector available. Instead, we traced one of the 3.3V lines to the F1 part and connected the 3.3V from Vout there.