UsbConnection.bulkTransfer 返回“-1".这是什么意思? [英] UsbConnection.bulkTransfer returns "-1". What does it mean?

问题描述

根据文档否定响应意味着失败.如何知道出了什么问题?是否有关于错误类型的完整文档?

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

更多好奇:我正在尝试通过 USB 上传 arduino 草图.首先，我通过关闭/打开 DTR/RTS 然后使用 Stk500 协议发送数据来引起引导加载程序的注意.如果通过 USB 在 mac/arduino 上运行(使用 rxtx 串行)，它工作正常，所以我认为它应该在 android AS-IS 上运行(只需更改串行)，但在 DTR/RTS 切换后无法发送数据.

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.

推荐答案

来自 bulkTransfer():

退货

成功传输的数据长度(或零)，或失败的负值

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

因此，如果您收到 -1，则表示您的数据传输失败.您可以查看 logcat，或使用断点找出原因.

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.

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