[fpc-pascal] USB Human Interface Devices

[James Richters]

>>Ah, I see. You declared EP as Plibusb_endpoint_descriptor (i.e., the pointer to an endpoint descriptor record), while in the original code it is a USBEndpointDescriptor (i.e., the record itself).
>>Your version is more memory efficient but uses "ugly pointer- arithmetic" by taking the address of an array element. However, just keep it as you implemented it.

Well that wasn’t my idea,  I was trying to get it to compile and I saw the existing function:
// helper function for method below, this can't be a local function
Function MyEndpointMatch(EP:Plibusb_endpoint_descriptor;Data:Pointer):Boolean;
Var bEndpointAddress : Byte;
Begin
  bEndpointAddress := (PtrUInt(Data) shr 0) and $FF;
  Result := (EP^.bEndpointAddress = bEndpointAddress);
End;

	It compiled and had the pointer, so I stuck a pointer in the one I was having a problem with and it compiled.... it was just a guess at how to get it to compile honestly. I figured that the other code had it so maybe something to do with the way things are defined now require it to be a pointer.. without the pointer it gives errors.

>>While reviewing your changes, I found a few small things.
>>Could you please keep the indenting and coding style as the existing code? This is especially for the constant and type declarations around TLibUsbPseudoHIDInterface (IIRC the >>keywords Type and Const should start at character 1, therefore you also should un-indent the 6+3 constants and the P/THIDReport record (except its final "End;" by 2 spaces.

	Yes, I will keep the indenting and coding style the same, No problem, I adjusted this as you requested.  I'll go through later and see if there are any other things I missed.. most of what I've done is cutting and pasting, but I'll keep it consistent.

>>Secondly, in your improved TLibUsbInterface.FindEndpoint, please revert the capitalization and indenting changes (i.e., capital "Function", "For", ..., and "do" and "then" in the same line, ... IMHO the only changed lines in comparison to the original code should be the extra variable EP, its assignment without range checks, and its use in MatchFunc and Exit.
	That was code the Jean sent me to get it to work under windows, but I wend an retrieved the original function and re-did the modifications to match the formatting.  It compiles fine without turning off range check, but I think there was some reason why Jean had to put them in there.. I'll leave it out for now unless we figure out why they were needed.

>>And thirdly, you introduced a class type TLibUsbInterruptInEndpoint, which is IMHO unused. If its so, please remove it. I like to avoid clutter. :-)
	I guess you are talking about line 128:   TLibUsbInterruptInEndpoint   = class; ?
              When I copied over { TUSBPseudoHIDInterface } and then renamed everything I needed it to be able to compile
	Line 211:    FIntrEndpoint : TLibUsbInterruptInEndpoint;  
              Without it I was getting libusboop.pas(212,21) Error: Identifier not found "TLibUsbInterruptInEndpoint"
              So I went back to usb.pas and copied that line over to prevent this error... perhaps I have it in the wrong place??

>>Apart form these cosmetic things, thank you very much for your effort!
   	No problem,  please let me know if I missed anything,  I'm happy to make it conform to the coding standards.  I’m a little confused by the capitalization, for example sometimes it's LibUsb,  sometimes it's Libusb.. I'm trying to figure out when the U is capitated and when it is not.... maybe it should always be one way or the other?  Please continue to correct me on anything you see.

>>I'm looking forward hearing from you your success when accessing a HID device (or call for help :-) ).

	Well..... since you asked... I'm having a real challenge trying to figure out how I can use all this to access my device... I'm just not familiar with this kind of programming... constructors, destructors, and all this inherited stuff, it's not what I am used to, I never have anything like that.. I know how to program in Turbo Pascal for DOS pretty much and normal in-line console style programming, but very little of anything past that, so a lot of this just goes over my head.   
	On top of that, I really don't understand USB communications at all, I have written programs with all kinds of features, programs that send e-mails, communicate over ethernet and serial connections, Modbus, etc... but this USB stuff is just not making any sense to me... and it seems like the python code I have as an example is so simple... you open the device, send and receive some stuff and close it...  but I don't really know python either, so I really don't understand everything going on there...
     	I still don't really see how to open and close the device or how to send or receive anything from it...  I'm struggling to see how the somewhat simple looking functions in HB04.py can be implemented....

I'm trying to use one of the examples to just open and close the device, but I am not successful with that,    Here is what I am trying to do:

I ran Test1library.pas and got the following:

Running "i:\programming\pas-libusb_test_dll\src\examples\test1library.exe "
Using libusb(x) v1.0.22.11312
Found 14 devices:
  Bus   1 Device   0: ID 8086:A36D,  port:   0, Speed: Unknown
  Bus   1 Device   5: ID 8087:0AAA,  port:  14, port path from HCD: 0, Speed: 12 Mbit/s (USB FullSpeed)
  Bus   1 Device  33: ID 0424:2734,  port:   1, port path from HCD: 0->1, Speed: 480 Mbit/s (USB HighSpeed)
  Bus   1 Device   7: ID 1B1C:0C15,  port:   2, port path from HCD: 0->9, Speed: 12 Mbit/s (USB FullSpeed)
  Bus   1 Device  16: ID 10CE:EB93,  port:   4, port path from HCD: 0, Speed: 12 Mbit/s (USB FullSpeed)
  Bus   1 Device   3: ID 05E3:0610,  port:   9, port path from HCD: 0, Speed: 480 Mbit/s (USB HighSpeed)
  Bus   1 Device  18: ID 04E8:61F5,  port:  19, port path from HCD: 0, Speed: unknown (4)
  Bus   1 Device   4: ID 1B1C:0C10,  port:  10, port path from HCD: 0, Speed: 12 Mbit/s (USB FullSpeed)
  Bus   1 Device  25: ID 0424:274C,  port:   5, port path from HCD: 0->1->1, Speed: 480 Mbit/s (USB HighSpeed)
  Bus   1 Device  34: ID 047D:1020,  port:   3, port path from HCD: 0->1->1, Speed: 1.5 Mbit/s (USB LowSpeed)
  Bus   1 Device  26: ID 1B1C:1B4F,  port:   4, port path from HCD: 0->1->1, Speed: 12 Mbit/s (USB FullSpeed)
  Bus   1 Device  12: ID 1A40:0101,  port:   1, port path from HCD: 0, Speed: 480 Mbit/s (USB HighSpeed)
  Bus   1 Device  14: ID 0C45:7403,  port:   2, port path from HCD: 0->1, Speed: 12 Mbit/s (USB FullSpeed)
  Bus   1 Device  30: ID 10C4:EA60,  port:   5, port path from HCD: 0, Speed: 12 Mbit/s (USB FullSpeed)

The one I want to try to use is this one:
  Bus   1 Device  16: ID 10CE:EB93,  port:   4, port path from HCD: 0, Speed: 12 Mbit/s (USB FullSpeed)
I assume that $10CE and $EB93 are the Vid and Pid??  

I tried plugging those into the following test program:

program test_open_WHB04B;

{$mode objfpc}{$H+}

uses
    Classes,SysUtils,MyDevice,LibUsbOop,LibUsbUtil;

procedure WHB04B_Device;
const
     WHB04B_VID= $10CE;
     WHB04B_PID= $EB93;
var
   Context   : TLibUsbContext;
   TheDevice : TMyDevice;
function CreateMatch: TLibUsbDeviceMatchVidPid;
   begin
      Result:= TLibUsbDeviceMatchVidPid.Create( Context, WHB04B_VID, WHB04B_PID);
   end;
begin
     Context := TLibUsbContext.Create;
     try
        TheDevice := TMyDevice.Create( Context, CreateMatch, '', CreateMatch);
     except
       on E : Exception do
         Begin
           WriteLn('Couldn''t connect to device: ',E.Message);
           Halt(1);
         End;
     End;
     WriteLn('Successfully connected to USB device ',IntToHex(WHB04B_VID,4),':',IntToHex(WHB04B_PID,4));
     WriteLn('Version:        ',TheDevice.GetVersion);
     WriteLn('Version String: ',TheDevice.GetVersionString);
     WriteLn('Status:         ',TheDevice.GetStatus);

     while true
     do
       Write( TheDevice.ReadString);

     TheDevice.Free;
     Context.Free;
end;

begin
     WHB04B_Device;
End.


When I run it I get:
Running "i:\programming\pas-libusb_test_dll\src\examples\test_open_whb04b.exe "
Couldn't connect to device: Access violation

When I try any of the other devices in the list I get:
Running "i:\programming\pas-libusb_test_dll\src\examples\test_open.exe "
Couldn't connect to device: Open: LIBUSB_ERROR_NO_DEVICE

What am I missing here?  Why can't I get this to work?

Any help is greatly appreciated!

James