/*  isp.c - part of USBasp  Autor..........: Thomas Fischl <tfischl@gmx.de>   Description....: Provides functions for communication/programming                   over ISP interface  Licence........: Free under certain conditions. See Documentation.  Creation Date..: 2005-02-23  Last change....: 2005-04-20*/#include <avr/io.h>#include "isp.h"#include "clock.h"#define spiHWdisable() SPCR = 0void spiHWenable() {  /* enable SPI, master, 375kHz SCK */  SPCR = (1 << SPE) | (1 << MSTR) | (1 << SPR1);  SPSR = (1 << SPI2X);}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);  /* 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 */  if (ispTransmit == ispTransmit_hw) {    spiHWenable();  }}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 = 32;  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();    }    }    return 1;  /* error: device dosn't answer */}uchar ispReadFlash(unsigned int address) {  ispTransmit(0x20 | ((address & 1) << 3));  ispTransmit(address >> 9);  ispTransmit(address >> 1);  return ispTransmit(0);}uchar ispWriteFlash(unsigned int address, uchar data, uchar pollmode) {  /* 0xFF is value after chip erase, so skip programming   if (data == 0xFF) {    return 0;  }  */  ispTransmit(0x40 | ((address & 1) << 3));  ispTransmit(address >> 9);  ispTransmit(address >> 1);  ispTransmit(data);  if (pollmode == 0)    return 0;  if (data == 0x7F) {    clockWait(15); /* wait 4,8 ms */    return 0;  } else {    /* polling flash */    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 --;      }    }    return 1; /* error */  }}uchar ispFlushPage(unsigned int 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   }  */}