ds28e01 copy返回值0x00求助
我使用ds28e01 CopyScratch的时候返回值总是0，实在弄不过去了，看手册好像是MAC验不过去，但是算法是官方给出的，我也不懂算法，没改过啊，为什么验不过去，下边是我的源码。我使用的事stm32的单片机。延时我是用示波器测过，delay_us可以实现1us为单位的延时。但是我还有个问题，你会看见我的代码while(1){if((WriteScratch(TargetAddress, buf))!= FALSE ) break;} 会出现while（1），原因是我发现我的操作并不是百分百的成功，有一定几率失败，虽然概率比较低，但是我看单总线的协议每次操作都是以复位为开始，所以我认为一次错误不影响下次操作，所以加了死循环，一直到成功为止，不知道这个有影响没？void write_bit(char bitval)
{
WR0_WIRE;
delay_us(2);
if(bitval==1)
WR1_WIRE;
delay_us(80);// hold value for remainder of timeslot
WR1_WIRE;
delay_us(2); // must add this delay because the cup frequence is 203MHZ.
}
void write_byte(char val)
{
unsigned char i;
unsigned char temp;
set_output();
for (i = 0; i < 8; i++) // writes byte, one bit at a time
{
temp = val>>i; // shifts val right ‘i’ spaces
temp &= 0x01; // copy that bit to temp
write_bit(temp); // write bit in temp into
}
delay_us(10);
}
int CopyScratch(short TargetAddr, INT8U *MACbuf)
{
unsigned char ch, i;
if ( (ow_reset())!=0 ) return FALSE;
write_byte(0xCC); //Skip ROM command
write_byte(0x55); // write scratch command
write_byte(TargetAddr%256 ); // write target address LSB
write_byte(0x00 ); // write target address MSB
write_byte(0x5f ); // write E/S byte
// waiting 3 ms for SHA-1 algorithm in DS28E01-100
delay_us(3000);
// send MAC to the DS28E01-100
for(i=0;i<20;i++) write_byte(MACbuf);
//delay 12ms for copying scratchpad to EEPROM in DS28E01-100
delay_us(6000);
delay_us(6000);
// return TRUE if it is toggling
ch=read_byte();
return ((ch == 0xAA) || (ch == 0x55));
}
写操作，最后一部需要调用CopyScratch。
intWrite8Byte(short TargetAddress, INT8U *buf, INT8U *PageData)
{
unsigned char BasicSecret;
//process the data writing
while(1){if((WriteScratch(TargetAddress, buf))!= FALSE ) break;}
while(1){if((ReadScratch(TargetAddress, buf))!= FALSE ) break;}
//calulating the MAC for CopyScratchpad
//fill the SHA-1 input buffer
ComputeBasicSecret(BasicSecret);
if( TargetAddress<0x80 )
{
memcpy(SHAVM_Message, BasicSecret, 4);
memcpy(&SHAVM_Message, PageData, 28);
memcpy(&SHAVM_Message, buf, 8);
SHAVM_Message=(TargetAddress>>5)&0x03;
memcpy(&SHAVM_Message, OW_RomID, 7);
memcpy(&SHAVM_Message, &BasicSecret, 4);
memset(&SHAVM_Message,0xff, 3);
SHAVM_Message = 0x80;
memset(&SHAVM_Message, 0x00, 6);
SHAVM_Message = 0x01;
SHAVM_Message = 0xB8;
}
if( TargetAddress>=0x88 )
{
memcpy(SHAVM_Message, BasicSecret, 4);
memcpy(&SHAVM_Message, BasicSecret, 8);
memcpy(&SHAVM_Message, PageData, 20);
memcpy(&SHAVM_Message, buf, 8);
SHAVM_Message=0x04;
memcpy(&SHAVM_Message, OW_RomID, 7);
memcpy(&SHAVM_Message, &BasicSecret, 4);
memset(&SHAVM_Message,0xff, 3);
SHAVM_Message = 0x80;
memset(&SHAVM_Message, 0x00, 6);
SHAVM_Message = 0x01;
SHAVM_Message = 0xB8;
}
SHAVM_Compute(); //MAC generated in SHAVM_MAC[]
while(1){if( (CopyScratch(TargetAddress, SHAVM_MAC))!=FALSE )return TRUE;}
}
void ComputeBasicSecret(unsigned char *DeviceBasicSecret)
{
if( BasicSecretOption )
{
//calculate unique 64-bit secret in the DS28E01-100
memset(&SHAVM_Message, 0x00, 32);
memcpy(SHAVM_Message, DeviceSecret, 4);
memset(&SHAVM_Message, 0xff, 4);
SHAVM_Message=OW_RomID&0x3f;
memcpy(&SHAVM_Message, &OW_RomID, 7);
memcpy(&SHAVM_Message, &DeviceSecret, 4);
memset(&SHAVM_Message,0xff, 3);
SHAVM_Message = 0x80;
memset(&SHAVM_Message, 0x00, 6);
SHAVM_Message = 0x01;
SHAVM_Message = 0xB8;
SHAVM_Compute(); //unique basic secret now in SHAVM_MAC[]
memcpy(DeviceBasicSecret, SHAVM_MAC, 8); //now unique 64-bit basic secret in DeviceBasicSecret
}
else
{
memcpy(DeviceBasicSecret, DeviceSecret, 8); //load basic 64-bit secret into DeviceBasicSecret
}
}
void SHAVM_Compute()
{
SHAVM_KTN=(long)0x5a827999;
SHAVM_KTN=(long)0x6ed9eba1;
SHAVM_KTN=(long)0x8f1bbcdc;
SHAVM_KTN=(long)0xca62c1d6;
for(SHAVM_cnt=0; SHAVM_cnt<16; SHAVM_cnt++)
{
SHAVM_MTword
= (((long)SHAVM_Message&0x00FF) << 24L)
| (((long)SHAVM_Message&0x00FF) << 16L)
| (((long)SHAVM_Message&0x00FF) << 8L)
|((long)SHAVM_Message&0x00FF);
}
for(; SHAVM_cnt<80; SHAVM_cnt++)
{
SHAVM_Temp
= SHAVM_MTword^ SHAVM_MTword
^ SHAVM_MTword ^ SHAVM_MTword;
SHAVM_MTword
= ((SHAVM_Temp << 1) & 0xFFFFFFFE)
| ((SHAVM_Temp >> 31) & 0x00000001);
}
SHAVM_Hash = 0x67452301;
SHAVM_Hash = 0xEFCDAB89;
SHAVM_Hash = 0x98BADCFE;
SHAVM_Hash = 0x10325476;
SHAVM_Hash = 0xC3D2E1F0;
for(SHAVM_cnt=0; SHAVM_cnt<80; SHAVM_cnt++)
{
SHAVM_Temp
= ((SHAVM_Hash << 5) & 0xFFFFFFE0)
| ((SHAVM_Hash >> 27) & 0x0000001F);
if(SHAVM_cnt<20)
SHAVM_Temp += ((SHAVM_Hash&SHAVM_Hash)|((~SHAVM_Hash)&SHAVM_Hash));
else if(SHAVM_cnt<40)
SHAVM_Temp += (SHAVM_Hash^SHAVM_Hash^SHAVM_Hash);
else if(SHAVM_cnt<60)
SHAVM_Temp += ((SHAVM_Hash&SHAVM_Hash)
|(SHAVM_Hash&SHAVM_Hash)
|(SHAVM_Hash&SHAVM_Hash));
else
SHAVM_Temp += (SHAVM_Hash^SHAVM_Hash^SHAVM_Hash);
SHAVM_Temp += SHAVM_Hash + SHAVM_KTN
+ SHAVM_MTword;
SHAVM_Hash = SHAVM_Hash;
SHAVM_Hash = SHAVM_Hash;
SHAVM_Hash
= ((SHAVM_Hash << 30) & 0xC0000000)
| ((SHAVM_Hash >> 2) & 0x3FFFFFFF);
SHAVM_Hash = SHAVM_Hash;
SHAVM_Hash = SHAVM_Temp;
}
//iButtons use LSB first, so we have to turn
//the result around a little bit.Instead of
//result A-B-C-D-E, our result is E-D-C-B-A,
//where each letter represents four bytes of
//the result.
for(SHAVM_cnt=0; SHAVM_cnt<5; SHAVM_cnt++)
{
SHAVM_Temp = SHAVM_Hash;
SHAVM_MAC[((SHAVM_cnt)*4)+0] = (unsigned char)SHAVM_Temp;
SHAVM_Temp >>= 8;
SHAVM_MAC[((SHAVM_cnt)*4)+1] = (unsigned char)SHAVM_Temp;
SHAVM_Temp >>= 8;
SHAVM_MAC[((SHAVM_cnt)*4)+2] = (unsigned char)SHAVM_Temp;
SHAVM_Temp >>= 8;
SHAVM_MAC[((SHAVM_cnt)*4)+3] = (unsigned char)SHAVM_Temp;
}
}
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