Direct Read with infinite timeout causing IOException: Queueing USB request failed

mik3y / usb-serial-for-android

Android USB host serial driver library for CDC, FTDI, Arduino and other devices.

MIT License

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Direct Read with infinite timeout causing IOException: Queueing USB request failed #346

Closed Manicben closed 3 years ago

Manicben commented 3 years ago

Hi there, when performing a direct read with infinite timeout by calling port.read(buffer, 0) with buffer size of 1, IOException: Queueing USB request failed is always raised, no matter what I do.

I'm on Android 11 and I've tested with an Arduino Uno (CDC driver), Arduino Nano (CH340 driver) and Sparkfun Pro Micro (ATMega32u4 with CDC driver), all give the same IOException . I've tried ignoring the exception and retrying forever, increasing the buffer size and adding a 10 second timeout (which results in the testConnection get_usb_status failing), but to no avail. I know for certain that the Arduinos are sending data to the Android phone and the correct baud rate is set on both sides, 9600.

On the other hand, I am able to perform a direct write using port.write(buffer, 0) with no issues and I can see the Arduinos have indeed received the written bytes.

kai-morich commented 3 years ago

If more than one byte is send, you might get this error as mentioned here. please try with buffer size 64.

Manicben commented 3 years ago

Hey there, thanks for the quick response!

I've now tried with byte[] buffer = new byte[64]; instead of byte[] buffer = new byte[1];, but this made no difference. I still get java.io.IOException: Queueing USB request failed thrown by port.read(buffer, 0).

If I try specifying a timeout, like 5000ms, I get java.io.IOException: USB get_status request failed from port.read(buffer, 5000).

EDIT: Also tried 128 and 1024 buffer size, no difference

kai-morich commented 3 years ago

does it work with the sample app included in this repo?

Manicben commented 3 years ago

It sure did, and I figured out my issues. One thing to note is that the application code I'm working with wasn't written by me and was previously using the Physicaloid library, which buffers read bytes internally and then serves that through its API.

I switched to using timeouts, made sense to for my use case anyway (but I think setting infinite timeouts would also work)
The application I was refactoring was expecting to be able to get back 1 byte at a time, this of course doesn't work here as all bytes must be written to the provided buffer at once, rather than providing a buffer of size 1 and internally buffering the rest as per Physicaloid's behaviour.
Once I refactored the application to instead iterate over the returned buffer instead of fetching 1 byte at a time, everything started working.

Now I only get those IOExceptions when the USB serial device is unplugged whilst the port is open (which is expected).

Many thanks, the example app proved that the application code was at fault, not the library, and that helped me narrow down what was wrong in the application!