UsbConnection.bulkTransfer returns "-1". What does it mean?

Question

According to the doc negative response means failure. How to know what's wrong? is there any full doc about error types?

For more curious: I'm trying to upload arduino sketch via USB. First i'm getting bootloader attention by turning DTR/RTS off/on and then sending data using Stk500 protocol. It's working fine if running on mac/arduino via usb (rxtx serial is used) so i think it should work on android AS-IS (just change serial), but it fails to send the data after DTR/RTS toggling.

Courteous

have you found any solution to this? I feel like xkcd.com/979 – Schiff

Answer 1

From the documentation for bulkTransfer():

Returns

length of data transferred (or zero) for success, or negative value for failure

So if you're getting -1, then it means your data transfer has failed. You could look into the logcat, or work with breakpoints to figure out why.

Davao

nothing in the log cat, no breakpoints can be set as it's android os class – Courteous

Minus one (-1) is also returned if the timeout is reached – Iolanthe

Answer 2

Well, after diving into log i was able to handle it - don't close/open usb few times in a row

Courteous

Answer 3

May be you forgot to claim the interface:

deviceConnection.ClaimInterface(interf, true);

Lianna