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fixing iso14443b (issue #103):

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- most significant bit of tag data (which happens to be the sign bit)
had been dropped when snooping (FPGA change)
- avoid trying to decode both tag and reader data when snooping (we don't
have the time to do so).
This commit is contained in:
pwpiwi 2015-06-02 22:27:14 +02:00
commit 5b95953d42
3 changed files with 60 additions and 49 deletions
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28
armsrc/iso14443b.c
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@ -158,7 +158,6 @@ static int Handle14443UartBit(int bit)
{
switch(Uart.state) {
case STATE_UNSYNCD:
LED_A_OFF();
if(!bit) {
// we went low, so this could be the beginning
// of an SOF
@ -272,8 +271,7 @@ static int Handle14443UartBit(int bit)
break;
}
// This row make the error blew circular buffer in hf 14b snoop
//if (Uart.state == STATE_ERROR_WAIT) LED_A_OFF(); // Error
if (Uart.state == STATE_UNSYNCD) LED_A_OFF();
return FALSE;
}
@ -1054,17 +1052,17 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
//-----------------------------------------------------------------------------
/*
* Memory usage for this function, (within BigBuf)
* 0-4095 : Demodulated samples receive (4096 bytes) - DEMOD_TRACE_SIZE
* 4096-6143 : Last Received command, 2048 bytes (reader->tag) - READER_TAG_BUFFER_SIZE
* 6144-8191 : Last Received command, 2048 bytes(tag->reader) - TAG_READER_BUFFER_SIZE
* 8192-9215 : DMA Buffer, 1024 bytes (samples) - DEMOD_DMA_BUFFER_SIZE
* Last Received command (reader->tag) - MAX_FRAME_SIZE
* Last Received command (tag->reader) - MAX_FRAME_SIZE
* DMA Buffer, 1024 bytes (samples) - DMA_BUFFER_SIZE
* Demodulated samples received - all the rest
*/
void RAMFUNC SnoopIso14443(void)
{
// We won't start recording the frames that we acquire until we trigger;
// a good trigger condition to get started is probably when we see a
// response from the tag.
int triggered = TRUE;
int triggered = TRUE; // TODO: set and evaluate trigger condition
FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
BigBuf_free();
@ -1110,6 +1108,9 @@ void RAMFUNC SnoopIso14443(void)
uint8_t parity[MAX_PARITY_SIZE];
LED_A_ON();
bool TagIsActive = FALSE;
bool ReaderIsActive = FALSE;
// And now we loop, receiving samples.
for(;;) {
int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
@ -1136,7 +1137,8 @@ void RAMFUNC SnoopIso14443(void)
samples += 2;
if(Handle14443UartBit(ci & 1)) {
if (!TagIsActive) { // no need to try decoding reader data if the tag is sending
if(Handle14443UartBit(ci & 0x01)) {
if(triggered && tracing) {
GetParity(Uart.output, Uart.byteCnt, parity);
LogTrace(Uart.output,Uart.byteCnt,samples, samples,parity,TRUE);
@ -1149,7 +1151,7 @@ void RAMFUNC SnoopIso14443(void)
/* false-triggered by the commands from the reader. */
DemodReset();
}
if(Handle14443UartBit(cq & 1)) {
if(Handle14443UartBit(cq & 0x01)) {
if(triggered && tracing) {
GetParity(Uart.output, Uart.byteCnt, parity);
LogTrace(Uart.output,Uart.byteCnt,samples, samples, parity, TRUE);
@ -1162,7 +1164,10 @@ void RAMFUNC SnoopIso14443(void)
/* false-triggered by the commands from the reader. */
DemodReset();
}
ReaderIsActive = (Uart.state != STATE_UNSYNCD);
}
if(!ReaderIsActive) { // no need to try decoding tag data if the reader is sending - and we cannot afford the time
if(Handle14443SamplesDemod(ci, cq)) {
//Use samples as a time measurement
@ -1179,6 +1184,9 @@ void RAMFUNC SnoopIso14443(void)
// And ready to receive another response.
DemodReset();
}
TagIsActive = (Demod.state != DEMOD_UNSYNCD);
}
WDT_HIT();
if(!tracing) {

BIN
fpga/fpga_hf.bit
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13
fpga/hi_read_rx_xcorr.v
View file

@ -99,8 +99,10 @@ end
reg [5:0] corr_i_cnt;
reg [5:0] corr_q_cnt;
// And a couple of registers in which to accumulate the correlations.
reg signed [15:0] corr_i_accum;
reg signed [15:0] corr_q_accum;
// we would add at most 32 times adc_d, the result can be held in 13 bits.
// Need one additional bit because it can be negative as well
reg signed [13:0] corr_i_accum;
reg signed [13:0] corr_q_accum;
reg signed [7:0] corr_i_out;
reg signed [7:0] corr_q_out;
@ -114,12 +116,13 @@ begin
begin
if(snoop)
begin
corr_i_out <= {corr_i_accum[12:6], after_hysteresis_prev};
corr_q_out <= {corr_q_accum[12:6], after_hysteresis};
// highest 7 significant bits of tag signal (signed), 1 bit reader signal:
corr_i_out <= {corr_i_accum[13:7], after_hysteresis_prev};
corr_q_out <= {corr_q_accum[13:7], after_hysteresis};
end
else
begin
// Only correlations need to be delivered.
// highest 8 significant bits of tag signal
corr_i_out <= corr_i_accum[13:6];
corr_q_out <= corr_q_accum[13:6];
end