43 lines
2.3 KiB
Markdown
43 lines
2.3 KiB
Markdown
# TinyUSB Host Keyboard Suspend/Freeze Issues on RP2040
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## Common Issues
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1. **Device Auto-Suspend:** Some keyboards automatically enter a low-power suspend mode if they don't detect activity or if the host stops sending Start-Of-Frame (SOF) packets.
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2. **Host Controller Freeze:** The RP2040 USB host controller can sometimes get into a state where it stops processing events, especially if there are signal integrity issues or if the `tuh_task()` is blocked for too long.
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3. **Missing Keep-Alive:** If the host doesn't send SOFs, the device will suspend. The RP2040 host should send SOFs automatically when configured as host.
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## `tuh_task` Usage
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- **Requirement:** `tuh_task()` must be called continuously and frequently in the main loop.
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- **Blocking:** It should not be blocked by long delays (like `sleep_ms` or blocking display updates) in the same thread.
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- **Current Code:** Your `hello_usb.cpp` calls `tuh_task()` in a tight loop, which is correct. The display updates are offloaded to Core 1, and the FIFO push is non-blocking (checked with `multicore_fifo_wready`), so Core 0 should remain responsive.
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## Potential Fixes & Debugging
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### 1. Handle Suspend/Resume Callbacks
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TinyUSB provides callbacks to notify the application when a device suspends or resumes. Implementing these can help determine if the device is actually suspending.
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Add these to your `hello_usb.cpp`:
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```cpp
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// Invoked when device is suspended
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void tuh_device_suspend_cb(uint8_t dev_addr) {
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printf("Device address = %d suspended\r\n", dev_addr);
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}
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// Invoked when device is resumed
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void tuh_device_resume_cb(uint8_t dev_addr) {
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printf("Device address = %d resumed\r\n", dev_addr);
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}
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```
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### 2. Force Resume
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If the device suspends and doesn't wake up, you might need to force a resume from the host side, although usually the device initiates resume (remote wakeup) or the host keeps it awake.
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### 3. Check Power
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Ensure the keyboard is receiving sufficient power. Some mechanical keyboards with LEDs draw significant current, potentially causing voltage drops that reset the USB connection or cause a freeze.
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### 4. Disable Suspend (Device Side)
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Some devices have internal settings to disable sleep, but this is device-specific.
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### 5. SDK/TinyUSB Version
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Ensure you are using a recent version of the Pico SDK and TinyUSB, as there have been fixes for RP2040 host mode stability.
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