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USB HID transmit problem

 
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johnnyD
Guest
USB HID transmit problem
PostPosted: Tue Sep 23, 2008 2:52 pm     Reply with quote
Hello ya'll!

I have modified the ex_usb_hid example. I can receive up to 64 bytes from a PC with no problem. Where I am getting stuck is trying to transmit x number of bytes to the PC. The problem is in the TX report count in the HID descriptor.

It works great if I set the TX report count to 5 in my HID descriptor and output 5 bytes, then the PC is able to read the data.

if I set the TX report count say to 10 and send out 9 bytes the PC doesn't read the data

is there any way to be able to transmit x number bytes that the PC can read?


Code:


#include <18F2550.h>
#device PASS_STRINGS=IN_RAM
#fuses HSPLL,NOWDT,NOPROTECT,NOLVP,NODEBUG,USBDIV,PLL5,CPUDIV1,VREGEN
#use delay(clock=48000000)

#define  USB_HID_DEVICE  TRUE
#define  USB_EP1_TX_ENABLE  USB_ENABLE_INTERRUPT   
#define  USB_EP1_TX_SIZE   64 
#define  USB_EP1_RX_ENABLE  USB_ENABLE_INTERRUPT   
#define  USB_EP1_RX_SIZE    64

#include <pic18_usb.h>   
#include <usb_desc_hid.h>   
#include <usb.c> 

int in_data[64]={0};
int out_data[5]={0x41,0x42,0x43,0x44,0x45};

void main()
{
  int1 ready=false;
  usb_init();
   while (TRUE)
   {
      usb_task();
               
      if (usb_enumerated())
      {
         usb_put_packet(1, out_data, 5, USB_DTS_TOGGLE);

         //while(usb_kbhit(1))
         //{
         // usb_get_packet(1,in_data,64);
          //ready=true;
         //}
         
        // if(ready)
        // {
          //  printf("%s\r",in_data);
          //  ready=false;
           
        // }
      }
   }
}




Here is my descriptor code

Code:


const char USB_CLASS_SPECIFIC_DESC[] = {
      6, 0, 255,        // Usage Page = Vendor Defined
      9, 1,              // Usage = IO device
      0xa1, 1,          // Collection = Application
      0x19, 1,          // Usage minimum
      0x29, 8,          // Usage maximum

      0x15, 0x80,       // Logical minimum (-128)
      0x25, 0x7F,       // Logical maximum (127)

      0x75, 8,          // Report size = 8 (bits)
      0x95, 5,          // TX report count
      0x81, 2,          // Input (Data, Var, Abs)
      0x19, 1,          // Usage minimum
      0x29, 8,          // Usage maximum
      0x75, 8,          // Report size = 8 (bits)
      0x95, 63,         // RX report count = 64 bits
      0x91, 2,          // Output (Data, Var, Abs)
      0xC0              // End Collection
   };

Dave_Mustaine
Guest
USB HID transmit problem
PostPosted: Tue Sep 23, 2008 4:06 pm     Reply with quote
Give this a try: The key is your data lengths must all match. The remainder of your packet will be all zeros but you can always parse them!

Good Luck


Code:


#include <18F2550.h>
#device PASS_STRINGS=IN_RAM
#fuses HSPLL,NOWDT,NOPROTECT,NOLVP,NODEBUG,USBDIV,PLL5,CPUDIV1,VREGEN
#use delay(clock=48000000)

#define  USB_HID_DEVICE  TRUE
#define  USB_EP1_TX_ENABLE  USB_ENABLE_INTERRUPT   
#define  USB_EP1_TX_SIZE   32
#define  USB_EP1_RX_ENABLE  USB_ENABLE_INTERRUPT   
#define  USB_EP1_RX_SIZE    32

#include <pic18_usb.h>   
#include <usb_desc_hid.h>   
#include <usb.c>
#include <string.h>

int in_data[32]={0};    // Set array to zero
int out_data[32]={0};  // Set array to zero

void main()
{
  int1 ready=false;
  strcpy(out_data,"HELLO THERE!");
  usb_init();
   while (TRUE)
   {
      usb_task();
               
      if (usb_enumerated())
      {
         while(usb_kbhit(1))
         {
          usb_get_packet(1,in_data,31);
          ready=true;
         }
         
        if(ready)
         {
            printf("%s\r",in_data);
            ready=false;
            usb_put_packet(1, out_data, 31, USB_DTS_TOGGLE);
         }
      }
   }
}




Now set your descriptor for the following

Code:


const char USB_CLASS_SPECIFIC_DESC[] = {
      6, 0, 255,        // Usage Page = Vendor Defined
      9, 1,             // Usage = IO device
      0xa1, 1,          // Collection = Application
      0x19, 1,          // Usage minimum
      0x29, 8,          // Usage maximum

      0x15, 0x80,       // Logical minimum (-128)
      0x25, 0x7F,       // Logical maximum (127)

      0x75, 8,          // Report size = 8 (bits)
      0x95, 31,         // TX report count = 32 bits
      0x81, 2,          // Input (Data, Var, Abs)
      0x19, 1,          // Usage minimum
      0x29, 8,          // Usage maximum
      0x75, 8,          // Report size = 8 (bits)
      0x95, 31,         // RX report count = 32 bits
      0x91, 2,          // Output (Data, Var, Abs)
      0xC0              // End Collection
   };

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