Bluetooth NES Advantage 2.0: it pairs to a Switch now

A while back I wrote up the first Bluetooth NES Advantage: an ESP32 board that takes the place of the controller’s cable and turns the 1987 arcade stick into a wireless gamepad. It worked, and it still does. But it only spoke one language, BLE HID, and that left two things off the table: a real Nintendo Switch, and playing on an actual NES.

2.0 fixes both.

The new board is a single PCB with a bare ESP32-WROOM-32E on it, and it runs in one of two modes:

• Switch mode emulates a Switch Pro Controller over Bluetooth Classic. It pairs straight to a Nintendo Switch with no adapter. That same mode pairs with an 8BitDo NES Retro Receiver, which is what lets the stick drive a real front-loader NES over Bluetooth. That was the one thing the first board could not do.
• BLE mode is the standard HID gamepad from before, for PCs, phones, SteamOS, BlueRetro, and emulators.

In both modes the board reads the Advantage’s original CD4021 shift registers directly, so turbo, slow motion, and the player-select slider behave the way they did in 1987. In BLE mode the slider even splits the stick into two gamepads, so two people can take turns without re-pairing.

The rest is the stuff that makes it good to live with:

• Wake on a button press out of a deep sleep that pulls microamps, so it survives sitting on a shelf.
• Low input latency: send-on-change with a 7.5 ms BLE connection interval.
• RGB status LEDs, battery monitoring, and a 5 V barrel jack for charging.
• A load-share power path, so you can keep playing while it charges.
• Browser-based config and over-the-air firmware updates. No cable, no app.

And like the first one, it goes in without butchering the controller. No case cutting, no extra buttons, and it charges through the hole the original cable came out of.

Hardware is KiCad, firmware is ESP-IDF, both open.

Where it stands: the boards are ordered and I am waiting on the prototypes. When they land I will populate a couple, bring the dual-mode Bluetooth stack up on real silicon, and make the Switch pairing as boring and reliable as it needs to be before anyone trusts it in a match. Assembled units and kits will go up at cajunpanda.com once it clears that bar.