Write data in an USB device using HID protocol. Why I have an error ?

Hi !

I try to pilot an usb device (a mini-circuits test board for ksn synthesizer) via USB HID protocol (hid.dll). The basic functions work, except when I try to write data. Indeed, when I write data using this line :

[res,h] = calllib('hidapi32','hid_write',hid.handle,pbuffer,uint64(length(wmsg)));

the answer is always ' -1'. Can you indicate me where is the mistake ?

Thanks.

the complete code:

if ~libisloaded('hidapi32')
[notfound, warnings] = loadlibrary('hidapi32_thunk_pcwin64.dll','hidapi.h','mfilename', 'mHeaderc');
end

calllib('hidapi32','hid_init');
libfunctions('hidapi32');

vendorID = 0;
productID = 0;
pointeur = calllib('hidapi32','hid_enumerate',uint16(vendorID),uint16(productID));
resultats = calllib('hidapi32','hid_free_enumeration',pointeur)

pNull = libpointer('uint16Ptr');
hid.vendorID = 8398;
hid.productID = 32;
pointeur = calllib('hidapi32','hid_enumerate',uint16(hid.vendorID),uint16(hid.productID));
str = calllib('hidapi32','hid_free_enumeration',pointeur);

[hid.handle,value] = calllib('hidapi32','hid_open',uint16(hid.vendorID),uint16(hid.productID),pNull);

hid.device = calllib('hidapi32','hid_open_path',str.path);

hid.nReadBuffer = 256;
hid.nWriteBuffer = 256;

buffer = zeros(1,hid.nReadBuffer);
pbuffer = libpointer('uint16Ptr',uint16(buffer));
[res,h] = calllib('hidapi32','hid_get_product_string',hid.handle,pbuffer,uint64(length(buffer)));
hid.product_string = sprintf('%s',char(pbuffer.Value));

buffer = zeros(1,hid.nReadBuffer);
pbuffer = libpointer('uint16Ptr',uint16(buffer));
[res,h] = calllib('hidapi32','hid_get_serial_number_string',hid.handle,pbuffer,uint64(length(buffer)));
hid.serial_number = pbuffer.Value(1);

buffer = zeros(1,hid.nReadBuffer);
pbuffer = libpointer('uint16Ptr',uint16(buffer));
[res,h] = calllib('hidapi32','hid_get_manufacturer_string',hid.handle,pbuffer,uint64(length(buffer)));
hid.manufacturer_string = sprintf('%s',char(pbuffer.Value));

pause(1)

buffer = zeros(1,hid.nWriteBuffer);
wmsg = [0 0 0 0 0 0 0 0 1 48 00 09 00 00 00 00 00 00];
wmsg(end+(hid.nWriteBuffer-length(wmsg))) = 0;
% create a unit8 pointer 
pbuffer = libpointer('uint8Ptr',uint8(wmsg));
% write the message
[res,h] = calllib('hidapi32','hid_write',hid.handle,pbuffer,uint64(length(wmsg)));
% check the response
if res ~= length(wmsg)
fprintf('hidapi write error: wrote %d, sent %d\n',(length(wmsg)-1),res);
end

calllib('hidapi32','hid_close',hid.handle);

Answer 1

[Guillaume]

It looks like you may be using this library (information that should have been included in your post).

The doc for hid_write says it returns -1 on error, so your call failed to write whatever it is you want to write. According to the doc, you can get more information about the error with hid_error. I suggest you try that, your problem is not caused by matlab.

errcause = calllib('hidapi32','hid_error',hid.handle)

[Joffray Guillory]

Thanks Guillaume for your answer.

Yes, I use the library Hidapi. Lot of people seems using this library and they meet no problem. I have just tried 'hid_error' method but it returns nothing (answer null).

My problem is not solved yet :/

[Guillaume]

Well then, if you have visual studio, I suggest you grab the source code for the library and use the debugging facilities of visual studio to find out what the problem is.

Otherwise, find a mailing list for that library or contact the developers.

Answer 2

[muhammad naseem]

try this one

i was also facing problem and i slove the problem this way

wmsg(end+(hid.nWriteBuffer-length(wmsg)) + 1) = 0;

Answer 3

[RABEHI]

Hello,

I have a simular project, and my problem is that when I give the vendorID and the productID, nothing happen !

the result is :

path: ''
              vendor_id: 0
             product_id: 0
          serial_number: []
         release_number: 0
    manufacturer_string: []
         product_string: []
             usage_page: 0
                  usage: 0
       interface_number: 0
                   next: []

I have to mention that I read the librery like the following :

addpath('C:\Windows\SysWOW64')
loadlibrary('hidapi')

Can I get some help please ?

Answer 4

[Melwin Thomas]

Instead of 'hid_write' use 'hid_send_feature_report'