Anne

Taking the kext file out, the Device was treated as an HID device. I have found two xcode projects which work, HID explorer and HID examples, but I am stuck right now, because these HID projects talk about elements, and USB prober talks about endpoint. I have not yet found what the link is between endpoints and elements.
Putting the kext file back in, I found several xcode projects for the USB, USBPrivateDAtaSample and SimpleUserClient (which still give me error messages) and USBSimple Example which I got to work: I put the vendor and product id, looked for interrupt pipes instead of bulk pipes, and added a synchronous readpipe command.

char gBuffer[8];

UInt32 numBytesRead;

numBytesRead = sizeof(gBuffer);

err = (*intf)->ReadPipe(intf, inPipeRef, gBuffer, &numBytesRead);

if (err) printf(“Unable to perform interrupt read %2x %4x %4x\n”,err_get_system(err),err_get_sub(err),err_get_code(err));

for (i = 1; i USElessthanSYMBOLHERE numBytesRead; i++) printf(“Read %x (%ld bytes) from interrupt endpoint\n”, gBuffer[i],gBuffer[0]);

(the first byte of data is a number, 7 usually, the rest are characters)

The key to success was being able to interpret the error message! I read how to print and interprete the error code ox38 ox00 ox2e8

http://developer.apple.com/qa/qa2001/qa1075.html

looking up in IOreturn.h, 0x028 is data overrun!

#define kIOReturnOverrun iokit_common_err(0x2e8) //

The other key to success was the apple USB forum site who helped with the error code

http://lists.apple.com/archives/Usb

where I was told that I should try reading at least maxPacketSize bytes, where maxPacketSize bytes is a USB prober info on the enpoint pipe. So I tried with a buffer size of 8, instead of 64 or 2, and bingo, the error message went away, and I was reading data!

Of course it helps that I have the PC opensource code to figure out what to do with the data!!!!

So a bright day, I talked to my device. Now I have to learn how to access it asynchronously.

This entry was posted on Wednesday, August 10th, 2005 at 4:39 pm and is filed under USB. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.