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em4x50read (work in progress)

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adam@algroup.co.uk 2009-07-06 23:02:12 +00:00
parent 846225d575
commit 955aa93faa
1 changed files with 143 additions and 0 deletions
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143
winsrc/command.cpp
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@ -256,6 +256,148 @@ static void CmdEM410xwatch(char *str)
} while (go);
}
/* Read the transmitted data of an EM4x50 tag
* Format:
*
* XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
* XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
* XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
* XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
* CCCCCCCC <- column parity bits
* 0 <- stop bit
* LW <- Listen Window
*
* This pattern repeats for every block of data being transmitted.
* Transmission starts with two Listen Windows (LW - a modulated
* pattern of 320 cycles each (32/32/128/64/64)).
*
* Note that this data may or may not be the UID. It is whatever data
* is stored in the blocks defined in the control word First and Last
* Word Read values. UID is stored in block 32.
*/
static void CmdEM4x50read(char *str)
{
int i, j, startblock, clock, skip, block, start, end, low, high;
BOOL complete= FALSE;
int tmpbuff[MAX_GRAPH_TRACE_LEN / 64];
char tmp[6];
high= low= 0;
clock= 64;
/* first get high and low values */
for (i = 0; i < GraphTraceLen; i++)
{
if (GraphBuffer[i] > high)
high = GraphBuffer[i];
else if (GraphBuffer[i] < low)
low = GraphBuffer[i];
}
/* populate a buffer with pulse lengths */
i= 0;
j= 0;
while(i < GraphTraceLen)
{
// measure from low to low
while(GraphBuffer[i] > low)
++i;
start= i;
while(GraphBuffer[i] < high)
++i;
while(GraphBuffer[i] > low)
++i;
tmpbuff[j++]= i - start;
}
/* look for data start - should be 2 pairs of LW (pulses of 192,128) */
start= -1;
skip= 0;
for (i= 0; i < j - 4 ; ++i)
{
skip += tmpbuff[i];
if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
if (tmpbuff[i+2] >= 190 && tmpbuff[i+2] <= 194)
if (tmpbuff[i+3] >= 126 && tmpbuff[i+3] <= 130)
{
start= i + 3;
break;
}
}
startblock= i + 3;
/* skip over the remainder of the LW */
skip += tmpbuff[i+1]+tmpbuff[i+2];
while(GraphBuffer[skip] > low)
++skip;
skip += 8;
/* now do it again to find the end */
end= start;
for (i += 3; i < j - 4 ; ++i)
{
end += tmpbuff[i];
if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
if (tmpbuff[i+2] >= 190 && tmpbuff[i+2] <= 194)
if (tmpbuff[i+3] >= 126 && tmpbuff[i+3] <= 130)
{
complete= TRUE;
break;
}
}
if (start >= 0)
PrintToScrollback("Found data at sample: %i",skip);
else
{
PrintToScrollback("No data found!");
PrintToScrollback("Try again with more samples.");
return;
}
if (!complete)
{
PrintToScrollback("*** Warning!");
PrintToScrollback("Partial data - no end found!");
PrintToScrollback("Try again with more samples.");
}
/* get rid of leading crap */
sprintf(tmp,"%i",skip);
CmdLtrim(tmp);
/* now work through remaining buffer printing out data blocks */
block= 0;
i= startblock;
while(block < 6)
{
PrintToScrollback("Block %i:", block);
// mandemod routine needs to be split so we can call it for data
// just print for now for debugging
Cmdmanchesterdemod("i 64");
skip= 0;
/* look for LW before start of next block */
for ( ; i < j - 4 ; ++i)
{
skip += tmpbuff[i];
if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
break;
}
while(GraphBuffer[skip] > low)
++skip;
skip += 8;
sprintf(tmp,"%i",skip);
CmdLtrim(tmp);
start += skip;
block++;
}
}
/* Read the ID of an EM410x tag.
* Format:
* 1111 1111 1 <-- standard non-repeatable header
@ -2434,6 +2576,7 @@ static struct {
"em410xsim", CmdEM410xsim,1, "<UID> -- Simulate EM410x tag",
"em410xread", CmdEM410xread,1, "[clock rate] -- Extract ID from EM410x tag",
"em410xwatch", CmdEM410xwatch,0, " Watches for EM410x tags",
"em4x50read", CmdEM4x50read,1, " Extract data from EM4x50 tag",
"exit", CmdQuit,1, " Exit program",
"flexdemod", CmdFlexdemod,1, " Demodulate samples for FlexPass",
"fpgaoff", CmdFPGAOff,0, " Set FPGA off", // ## FPGA Control