The initial code assumed phase shift modulation only. Lately,
xcorrelation is also used for load modulation. But the initial
the assumption that 11 bits are enough isn't true for load
modulation.
This change extends the registers by 2 bits and compresses the
uper bits to preserve the sensitivity on the lower end.
- Even tough legic tags transmit just AM using xcorrelation
results in a significantly better signal quality.
- Switching from bit bang to a hardware based ssc frees
up CPU time for other tasks e.g. demodulation
- fix: IQ demodulator (FPGA)
- fix: approximately align reader signal delay to tag response delay (FPGA)
- fix: remove deprecated RSSI calculation to improve decoder speed (iso14443b.c)
- fix: better approximation of signal amplitude to avoid false carrier detection (iso14443b.c)
- fix: remove initial power off in iso14443b raw command (iso14443b.c)
- add: enable tracing for iso14443b raw command (iso14443b.c)
- fix: client crashed when checking CRC for incomplete responses (iso14433b.c)
- speeding up snoop to avoid circular buffer overflow
- added some comments for better documentation
- rename functions (iso14443 -> iso14443b)
- remove unused code in hi_read_rx_xcorr.v
- 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).