/*  isp.c - part of USBasp  Autor..........: Thomas Fischl <tfischl@gmx.de>   Description....: Provides functions for communication/programming                   over ISP interface  Licence........: GNU GPL v2 (see Readme.txt)  Creation Date..: 2005-02-23  Last change....: 2007-07-23*/#include <avr/io.h>#include "isp.h"#include "clock.h"#define spiHWdisable() SPCR = 0void spiHWenable(uchar type) {	if(type == 0){			  /* enable SPI, master, 375kHz SCK */	  SPCR = (1 << SPE) | (1 << MSTR) | (1 << SPR1);	  SPSR = (1 << SPI2X);	}else{	  				/* enable SPI, master, 93.75kHz SCK */	  SPCR = (1 << SPE) | (1 << MSTR) | (1 << SPR1);	  SPSR = 0;	}}void ispSetSCKOption(uchar option) {  if (option == 0) {    /* use software spi */    ispTransmit = ispTransmit_sw;    //    spiHWdisable();  } else {    /* use hardware spi */    ispTransmit = ispTransmit_hw;  }}  void ispDelay() {  uint8_t starttime = TIMERVALUE;  while ((uint8_t) (TIMERVALUE - starttime) < 12) { }}void ispConnect() {  /* all ISP pins are inputs before */  /* now set output pins */  ISP_DDR |= (1 << ISP_RST) | (1 << ISP_SCK) | (1 << ISP_MOSI);	if(chip==ATM){			/* reset device */ 		ISP_OUT &= ~(1 << ISP_RST);   /* RST low */  	ISP_OUT &= ~(1 << ISP_SCK);   /* SCK low */  		/* positive reset pulse > 2 SCK (target) */  	ispDelay();  	ISP_OUT |= (1 << ISP_RST);    /* RST high */  	ispDelay();                  	ISP_OUT &= ~(1 << ISP_RST);   /* RST low */  	ispDelay();  	if(ispTransmit==ispTransmit_hw){    	spiHWenable(0);  	}    }else{  	  /* reset device */  	ISP_OUT |= (1 << ISP_RST);   /* RST high */  	ISP_OUT &= ~(1 << ISP_SCK);   /* SCK low */  		/* positive reset pulse > 2 SCK (target) */  	clockWait(15);  	ISP_OUT &= ~(1 << ISP_RST);    /* RST low */ 		clockWait(15);                  	ISP_OUT |= (1 << ISP_RST);   /* RST high */  	clockWait(15);	}}void ispDisconnect() {    /* set all ISP pins inputs */  ISP_DDR &= ~((1 << ISP_RST) | (1 << ISP_SCK) | (1 << ISP_MOSI));  /* switch pullups off */  ISP_OUT &= ~((1 << ISP_RST) | (1 << ISP_SCK) | (1 << ISP_MOSI));  /* disable hardware SPI */  spiHWdisable();}uchar ispTransmit_sw(uchar send_byte) {  uchar rec_byte = 0;  uchar i;  for (i = 0; i < 8; i++) {    /* set MSB to MOSI-pin */    if ((send_byte & 0x80) != 0) {      ISP_OUT |= (1 << ISP_MOSI);  /* MOSI high */    } else {      ISP_OUT &= ~(1 << ISP_MOSI); /* MOSI low */    }    /* shift to next bit */    send_byte  = send_byte << 1;    /* receive data */    rec_byte = rec_byte << 1;    if ((ISP_IN & (1 << ISP_MISO)) != 0) {      rec_byte++;    }    /* pulse SCK */    ISP_OUT |= (1 << ISP_SCK);     /* SCK high */    ispDelay();    ISP_OUT &= ~(1 << ISP_SCK);    /* SCK low */    ispDelay();  }      return rec_byte;}uchar ispTransmit_hw(uchar send_byte) {  SPDR = send_byte;    while (!(SPSR & (1 << SPIF)));  return SPDR;}    uchar ispEnterProgrammingMode() {  uchar check;  uchar count=16;  chip=ATM;  ispConnect();  while(count--){    ispTransmit(0xAC);    ispTransmit(0x53);    check=ispTransmit(0);    ispTransmit(0);        if(check==0x53){      return 0;    }    spiHWdisable();        /* pulse SCK */    ISP_OUT|=(1<<ISP_SCK);     /* SCK high */    ispDelay();    ISP_OUT&= ~(1<<ISP_SCK);    /* SCK low */    ispDelay();    if(ispTransmit==ispTransmit_hw)spiHWenable(0);   }    count=16;  chip=S5x;  if(ispTransmit==ispTransmit_hw)spiHWenable(1);  ispConnect();  while(count--){    ispTransmit(0xAC);    ispTransmit(0x53);    ispTransmit(0);    check=ispTransmit(0);        if(check==0x69){      return 0;    }    spiHWdisable();    /* pulse SCK */    ISP_OUT|=(1<<ISP_SCK);     /* SCK high */    ispDelay();    ISP_OUT&= ~(1<<ISP_SCK);    /* SCK low */    ispDelay();    if(ispTransmit==ispTransmit_hw)spiHWenable(1);  }    return 1;  /* error: device dosn't answer */}uchar ispReadFlash(unsigned long address) {	if(chip==ATM){ 	 ispTransmit(0x20|((address & 1)<<3));  	ispTransmit(address>>9);  	ispTransmit(address>>1);  }else{  	ispTransmit(0x20);  	ispTransmit(address>>8);  	ispTransmit(address);  }  return ispTransmit(0);}uchar ispWriteFlash(unsigned long address, uchar data, uchar pollmode) {	if(chip==ATM){  	ispTransmit(0x40|((address&1)<<3));  	ispTransmit(address>>9);  	ispTransmit(address>>1);  	ispTransmit(data);  	if(pollmode==0)return 0;  	if(data == 0x7F){    	clockWait(15);    	return 0; 	  }else{    	uchar retries=30;    	uint8_t starttime=TIMERVALUE;    	while(retries!=0){    	  if(ispReadFlash(address)!=0x7F)return 0;         	  if((uint8_t)(TIMERVALUE-starttime)>CLOCK_T_320us){					starttime=TIMERVALUE;					retries--;    	  }    	}    }   }else{      ispTransmit(0x40);  	ispTransmit(address >> 8);  	ispTransmit(address);  	ispTransmit(data);  	clockWait(2);  	return 0;   }   return 1; /* error */}uchar ispFlushPage(unsigned long address, uchar pollvalue) {  ispTransmit(0x4C);  ispTransmit(address >> 9);  ispTransmit(address >> 1);  ispTransmit(0);  if (pollvalue == 0xFF) {    clockWait(15);    return 0;  } else {    /* polling flash */    uchar retries = 30;    uint8_t starttime = TIMERVALUE;    while (retries != 0) {      if (ispReadFlash(address) != 0xFF) {	return 0;      };      if ((uint8_t) (TIMERVALUE - starttime) > CLOCK_T_320us) {	starttime = TIMERVALUE;	retries --;      }    }    return 1; /* error */  }    }uchar ispReadEEPROM(unsigned int address) {  ispTransmit(0xA0);  ispTransmit(address >> 8);  ispTransmit(address);  return ispTransmit(0);}uchar ispWriteEEPROM(unsigned int address, uchar data) {  ispTransmit(0xC0);  ispTransmit(address >> 8);  ispTransmit(address);  ispTransmit(data);  clockWait(30); // wait 9,6 ms   return 0;  /*   if (data == 0xFF) {    clockWait(30); // wait 9,6 ms     return 0;  } else {    // polling eeprom     uchar retries = 30; // about 9,6 ms     uint8_t starttime = TIMERVALUE;    while (retries != 0) {      if (ispReadEEPROM(address) != 0xFF) {	return 0;      };      if ((uint8_t) (TIMERVALUE - starttime) > CLOCK_T_320us) {	starttime = TIMERVALUE;	retries --;      }    }    return 1; // error   }  */}