Pro Controller Latency Explainer

Why the Nintendo Switch Pro Controller Has Extra USB Latency

The Nintendo Switch Pro Controller often shows more latency over USB than over Bluetooth, and the delay can be variable by up to a frame in 60 FPS titles. This behavior is caused by the controller’s internal architecture, not the USB cable or the Switch console.

Dual-MCU Design

Inside the Pro Controller, Nintendo uses two microcontrollers:

  1. Broadcom MCU

    • Reads all buttons and stick inputs

    • Manages Bluetooth communication

    • Is firmware-compatible with Joy-Con controllers

  2. STM32 MCU

    • Provides USB connectivity

    • Communicates with the Broadcom MCU via UART

    • Converts internal UART input data into USB HID packets

This design allows Nintendo to reuse Joy-Con firmware logic in a Pro Controller form factor without rewriting core input and state handling.

Why USB Is Slower

In USB mode, data travels through this internal path:

Input → Broadcom MCU → UART → STM32 → USB → Switch

In Bluetooth mode, the STM32 is bypassed:

Input → Broadcom MCU → Bluetooth → Switch

Because two MCUs must coordinate asynchronously, USB mode introduces:

  • UART polling delay

  • STM32 buffering / packet scheduling

  • USB HID framing

  • Switch USB polling alignment

These timing layers create inconsistent latency, which is why USB mode can feel slightly slower or less predictable than Bluetooth.

Bluetooth is the native controller signaling path, and Nintendo optimized the Broadcom MCU and Switch OS around it. USB was implemented as a translation layer, not a low-latency transport.

Feature Clue: Amiibo

Because certain subsystems (e.g., NFC / Amiibo) live directly on the Broadcom MCU and are never exposed through the STM32, Amiibo does not work over USB, further confirming that USB mode is a limited bridge, not a native protocol.

Comparison: RP2040-Based Controllers (GC Ultimate / ProGCC)

Other modern Switch-compatible controllers such as GC Ultimate and ProGCC do not exhibit the same USB latency behavior.

Why?

  • These devices use a single RP2040 MCU

  • The RP2040:

    • Reads inputs directly

    • Generates USB HID packets directly

    • Does not use UART translation or a bridging microcontroller

This creates a direct input → USB HID path, eliminating the variable internal delay seen in the Pro Controller.

Input → RP2040 → USB → Switch

As a result, USB mode on RP2040-based controllers is far more consistent and often lower latency than wired mode on the official Pro Controller.

Bottom Line

  • The Switch Pro Controller’s extra USB delay is caused by its internal UART-to-USB bridging architecture, not the console or cable.

  • Bluetooth mode is typically lower latency and more consistent on the official Pro Controller.

  • Controllers that use a single MCU with native USB (e.g., RP2040) avoid this problem entirely.