🪲[BUG] USB Flash drive descriptor read fails unless log level is 3
Closed this issue · 2 comments
Describe the bug you encountered:
I realize this is not supported yet officially, but I am attempting to implement a USB MSC Host with the Pico-PIO-USB. If log level is 1, enumeration fails getting the USB descriptor of the flash drive with a printout
[1:0] Control FAILED
If I set the log level to 3, enumeration succeeds. The flash drive mounts and I am able to read the block size and block count.
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What did you expect to happen instead?
I expected the host to at least be able to read the USB device descriptor even if USB MSC Host is not yet supported.
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What actually happened in your case?
Descriptor read fails every time.
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Additional information
I am using a Raspberry Pi Pico board and a USB A breakout board that I modified to insert 27 ohm SMT resistors in series with the D+ and D- pins. I have routed D+ to Pico board pin 1 and D- to Pico board pin 2 as per default. I am using a Picoprobe for debug and for UART output; UART0 is the debug UART; I am using Pico board pins 21 and 22 for the UART: i.e., in my CMakeLists.txt
PICO_DEFAULT_UART_TX_PIN=16
PICO_DEFAULT_UART_RX_PIN=17
Power is supplied by my PC via the Pico Board microUSB connector. The USB device mode on the microUSB connector is not yet initialized. I have tested this hardware system with a USB Keyboard connected to the USB A + sample code and with 3 different MIDI devices connected to the USB A + my own USB MIDI host code. All work correctly.
I have a DreamSourceLab logic analyzer, so I can dig deeper. Any hints as to where I should look? Are there PulseView traces that you would recommend I examine?
I think the issue may be that the reset recovery time interval is not being obeyed. See USB Spec section 7.1.7.3 Figure 7-29 timing interval delta-t6 must be 10ms. I measure less than 1ms between the end of bus reset to the start of the first setup packet.
When the log level is 3, I measure about 8.8ms between reset end and the first setup packet. That seems to be enough time for
the flash drive to recover from reset.
I will close this issue for this project. The bug should be fixed in tinyusb hcd_pio_usb.c function hcd_port_reset_end() because
it seems hcd_pio_usb.c has control over the reset timing.