interface.c

我制作过的usbisp资料, 仅供参考

/**	\file 
	<b>USB receive and transmit</b><br>
	Autor: Matthias Wei遝r<br>
	Copyright 2005: Matthias Wei遝r<br>
	License: QPL (see license.txt)
	<hr>
*/

#include <avr/io.h>
#include "tools.h"
#include "interface.h"

#include "config.h"

unsigned char checksum;

#ifdef CONFIG_INTERFACE_USB

	//Hardware
	#define	USB_TXE		(PINB&BIT6_POS)
	#define	USB_RXF		(PINC&BIT3_POS)
	#define	USB_RD_ON	PORTC&=BIT1_NEG
	#define	USB_RD_OFF	PORTC|=BIT1_POS
	#define	USB_WR_ON	PORTC|=BIT2_POS
	#define	USB_WR_OFF	PORTC&=BIT2_NEG
	
	/**
		Initializes the usb interface
	*/
	void interface_init(void)
	{
		PORTC |= BIT1_POS;			//USB_RD inactive
		DDRC |= BIT1_POS|BIT2_POS;	//USB_RD, USB_WR as output
	}
	
	/**
		Reads a byte from the USB interface
		
		@return received character or -1 if no character has been received
	*/
	signed int interface_getc(void)
	{
		unsigned char t;
		
		if(!USB_RXF)
		{	
			USB_RD_ON;
			asm("NOP");
			t = PIND;
			USB_RD_OFF;
			
			return t;
		}
		else return -1;
	}
	
	/**
		Writes a byte to the USB
		
		@param t Byte to be written	
	*/
	void interface_putc(unsigned char t)
	{
		while(USB_TXE);
		
		//PORTD auf Ausgang
		DDRD = 0xFF;
		//Daten auf den Port
		PORTD = t;
		
		USB_WR_ON;
		USB_WR_OFF;
		
		//PORTC auf Eingang
		DDRD = 0x00;
		//Pull-Ups ein
		PORTD = 0xFF;
		
		checksum ^= t;
	}
	
#endif

#ifdef CONFIG_INTERFACE_RS232
		
	#define USART_BAUD_RATE 115200   //38400
	#define USART_BAUD_SELECT (F_CPU/(USART_BAUD_RATE*16l)-1)
	
	/**
		Initializes the rs232 interface
		
		Autor: Lukas Salzburger
	*/
	void interface_init(void)
	{
		UCSRB =  (1<<RXEN) | (1<<TXEN);
    	UBRRL = (unsigned char) USART_BAUD_SELECT;
		UBRRH = (unsigned char) (USART_BAUD_SELECT>>8);
	}
	
	/**
		Reads a byte from the UART interface
		
		Autor: Lukas Salzburger
		
		@return received character or -1 if no character has been received
	*/
	signed int interface_getc(void) 
	{
		
		if (UCSRA & (1<<RXC)) 
		{
			return UDR;
		}
		else return -1;
	}
	
	/**
		Writes a byte to the UART
		
		Autor: Lukas Salzburger
		
		@param t Byte to be written	
	*/
	void interface_putc(unsigned char t) 
	{
	
		while (!(UCSRA & (1<<UDRE)));
		
		UDR = t;
		checksum ^= t;
	}

#endif
	
/**
	Writes a string to USB
	
	@param s The string to be send
*/
void interface_print(unsigned char *s)
{
	while(*s)
	{
		interface_putc(*s);
		s++;
	}
}

/**
	Sends a 16 bit value over the USB
	MSB first
	
	@param t Value to be send
*/
void interface_put16(unsigned int t)
{
	interface_putc((t>>8)&0xFF);
	interface_putc((t>>0)&0xFF);
}

/**
	Resets the checksum accumulator
*/
void interface_reset_check(void)
{
	checksum=0;
}

/**
	Sends the accumulated checksum
*/
void interface_send_check(void)
{
	interface_putc(checksum);
	checksum=0;
}