usb_vuart_lib.c

C89c51 usb驱动程序,实现了usb转串口的功能,提供了一个虚拟的串口

/*C**************************************************************************
* NAME:         usb_vuart_lib.c
*----------------------------------------------------------------------------
* Copyright (c) 2003 Atmel.
*----------------------------------------------------------------------------
* RELEASE:      c5131-usb-cdc-1_0_1      
* REVISION:     1.2     
*----------------------------------------------------------------------------
* PURPOSE: 
* This firmware library file provides USB "Virtual UART" functions
* which allow the USB interface to resemble a UART to higher-level firmware.
* These functions require lower-level USB firmware library modules:
* "usb_cdc_enum.c" and "usb_drv.c".
*
* The USB host requires standard 'CDC' driver software which provides
* a "virtual" COM port to the host PC application.
*****************************************************************************/
/*_____ I N C L U D E S ____________________________________________________*/

#include  "usb_config.h"
#include  "a89c5131.h"
#include  "c5131_drv.h"
#include  "usb_drv.h"
#include  "usb_cdc_enum.h"
#include  "usb_vuart_lib.h"

/*_____ M A C R O S ________________________________________________________*/

/*_____ D E F I N I T I O N ________________________________________________*/

Uchar tx_counter;
Uchar rx_counter;

/*_____ D E C L A R A T I O N ______________________________________________*/

/*F**************************************************************************
* NAME: usb_vuart_init
*----------------------------------------------------------------------------
* PARAMS:
* delay:    none
* return:   none
*----------------------------------------------------------------------------
* PURPOSE: 
* This function initializes the UART USB library.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE: 
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/

void usb_vuart_init(void)
{
  tx_counter = 0;
  rx_counter = 0;
}

/*F**************************************************************************
* NAME: usb_vuart_rx_data_avail
*----------------------------------------------------------------------------
* PARAMS:
* delay:    none
* return:   boolean TRUE if a byte is ready to be read, FALSE otherwise
*----------------------------------------------------------------------------
* PURPOSE: 
* This function checks if a character has been received on the USB bus.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE: 
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
bit usb_vuart_rx_data_avail(void)
{
  if (!rx_counter)
  { 
    Usb_select_ep(RX_EP);
    if (Usb_rx_complete()) 
    	{ rx_counter = usb_get_nb_byte(); if (!rx_counter) Usb_clear_rx(); }
  }
  return (rx_counter!=0);
}

/*F**************************************************************************
* NAME: usb_vuart_getchar
*----------------------------------------------------------------------------
* PARAMS:
* delay:    none
* return:   Uchar, read data from USB
*----------------------------------------------------------------------------
* PURPOSE: 
* This function reads one byte from the USB bus
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
* If one byte is present in the USB fifo, this byte is returned. If no data
* is present in the USB fifo, this function waits for USB data.
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
char usb_vuart_getchar(void)
{
  register Uchar data_rx;

  Usb_select_ep(RX_EP);
  if (!rx_counter) while (!usb_vuart_rx_data_avail());
  data_rx=Usb_read_byte();
  rx_counter--;
  if (!rx_counter) Usb_clear_rx();
  return data_rx;
}


/*F**************************************************************************
* NAME: usb_vuart_tx_ready
*----------------------------------------------------------------------------
* PARAMS:
* delay:    none
* return:   Boolean. TRUE if the firmware can write a new byte to transmit.
* FALSE oterwise.
*----------------------------------------------------------------------------
* PURPOSE: 
* This function checks if the USB emission buffer is ready to accept at
* at least 1 byte
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE: 
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
bit usb_vuart_tx_ready(void)
{
  if ((Usb_tx_ready())||(Usb_tx_complete())) { return FALSE; }
  return TRUE;
}

/*F**************************************************************************
* NAME: usb_vuart_putchar
*----------------------------------------------------------------------------
* PARAMS:
* Uchar:    data to send through USB
* delay:    none
* return:   data to send
*----------------------------------------------------------------------------
* PURPOSE: 
* This function fills the USB transmit buffer with the new data. This buffer
* is sent if complete. To flush this buffer before waiting until full, launch
* the usb_vuart_flush() function.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE: 
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
char usb_vuart_putchar(Uchar data_to_send)
{
  Usb_select_ep(TX_EP);
  if ((Usb_tx_ready())||(Usb_tx_complete())) 
  	{ while(!Usb_tx_complete()); Usb_clear_tx_complete(); }
  Usb_write_byte(data_to_send);
  tx_counter++;
  if (tx_counter >= TX_EP_SIZE) usb_vuart_flush(); 
  return data_to_send;
}

/*F**************************************************************************
* NAME: usb_vuart_flush
*----------------------------------------------------------------------------
* PARAMS:
* delay:    none
* return:   none
*----------------------------------------------------------------------------
* PURPOSE: 
* This function sends the data stored in the USB transmit buffer.
* This function does nothing if there is no data in the buffer.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE: 
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
void usb_vuart_flush (void)
{
  if (tx_counter)
  {
    Usb_select_ep(TX_EP);
    Usb_set_tx_ready();
    tx_counter = 0;
  }
}