[libhid-discuss] HID_Interrupt_write reports OK, but no action on device..

[Charles Lepple]

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Thanks.]

On Aug 31, 2009, at 4:24 PM, Neil Sutton wrote:

> Hi All,
>
> I have been bashing my head against the keyboard all day trying to  
> make my little USB relay work under Linux (Ubuntu Jaunty if it  
> matters)
> I don't have a great deal of experience with linux but after some  
> reading I discovered that the best way to talk to the relay (which  
> detects as a HID device) was to use the libhid library.
>
> So far I have tweaked the example code so that it looks for my  
> device and set up the commands to make an interrupt write to try and  
> enable the relays.
>
> In Windows I successfully control the device using VB and issue the  
> commands to control the relays using Convert.ToByte(Int)
> The board has 4 relays and by issuing Convert.ToByte(6) for example  
> I can open a single relay, Convert.ToByte(5) closes the relay.
> (7) and (8) control another relay.. you get the idea.

In that case, you probably want to send 6 and 5, or 7 and 8.

> Now the example code reports back ok when I issue the interrupt  
> write but nothing happens on the device.
> I think I may be sending the wrong commands but I'm not too sure..

Are you sure that the Windows code is using an interrupt write, and  
not a control transfer? Is it using an output usage rather than a  
feature usage?

Also, what timeout are you using under Windows?

> I figured that I should send one byte, of 8 bits..? so I have tried  
> to send 0xFF and also 255 but neither does anything.

0xff and 255 get converted to the same 8-bit quantity when sent.

> The lsusb output is here for my device;
> http://pastebin.com/m48287552
>
> Here is the modified hid_test.c that I'm currently using;
> http://pastebin.com/d1a6f40da
>
> Any pointers would be appreciated!
>
> Thanks
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