FeliCa reading was broken on every card tested: 'hf felica reader' returned PM3_ETIMEOUT while the tag was answering correctly. The cause was in the FPGA demodulator, not the ARM.
fpga/hi_flite.v
---------------
Adaptive hysteresis thresholds. The envelope tracker clamped curmin to <= 70 and curmax to >= 180, so curminthres/curmaxthres were pinned near 91/160 no
matter where the signal actually sat. Measured on a RDV4 with the field on, the peak detector idles near 112 and a tag swings it by about +/-35, ie entirely
inside that window - so nothing ever crossed a threshold and every frame demodulated as a constant. The band is now derived from the tracked envelope,
3/16 of its span, floored at +/- 8 to stay clear of the 4..6 counts of carrier ripple.
Matched-filter bit detector. The slicer counted comparator trips (+1 above curmaxthres, -1 below curminthres, repeat the last crossing direction inside
the dead band), so every bit depended on where the band happened to sit. A mispositioned band railed the output to a constant and, since only the stable
branch can recompute thresholds or desync, it stayed that way for the rest of the session. It also discarded amplitude, gaining nothing from 32x
oversampling. Each half-bit is now integrated in the ADC domain and the larger half wins. Thresholds still drive bit phase and the desync, they no longer
decide bit values, so a clipped or mispositioned envelope can no longer rail the output.
Polarity lock guard. try_sync arms part way through a half-bit, so the first decision after arming is meaningless and could latch 'zero' inverted, decoding
the whole frame with the wrong polarity and losing the sync word. Skip the first two decisions; the preamble is 48 bits.
curbit re-timing. The bit decision was made in the bit-phase domain, which is aligned to the tag's edges, but sampled by the SSC in the carrier domain. The
ARM could latch a bit mid-transition at a phase that varied per frame. Both run at 64 carrier periods per bit, so re-timing curbit half an SSP bit away from the
sampling edge is a re-time, not a resample.
Envelope watchdog. FPGA registers persist across PM3 commands - only a bitstream reload clears them - so the tracker could enter a state it never left and the
first command after the client started would work while every one after it failed. Force a re-centre when the demodulator has not reached a known-good idle
for 19.3 ms, held off at the start of each frame so it cannot fire mid-reply.
state is marked (* fsm_extract = 'no' *). The project synthesises with -fsm_style bram; once XST recognised this register as a state machine it placed
the state ROM in a block RAM, and the xc2s30's six were already spoken for. MAP then failed to fit with nothing but a generic 'design is too large' error, no
BITGEN, and no new bitstream.
armsrc/felica.c
---------------
- felica_select_card() returning 4 (response too short for IDm+PMm) fell through to PM3_SUCCESS, so 'hf felica reader' reported an all-zero IDm as a good read.
- After a poll timeout the code still read FelicaFrame; with a stale POLLING_RES and len == 0, check_crc() was handed (len - 2) as a size_t, ie 65534.
- WaitForFelicaReply() could only time out from STATE_UNSYNCD/TRYING_SYNC and would spin forever if a frame never completed.
- felica_sniff() decremented and broke before LogTrace, so '-s 10' logged nine frames and '-s 0' logged none. CRC-failed noise no longer pollutes the trace.
- felica_sendraw() sent no reply at all for some flag combinations, leaving the client blocked until its own timeout.
- Polling used time slot 0 only, so several cards in the field collided forever. Retries now widen the TSN window.
- BuildFliteRdblk() warned about a bad block count and built the frame anyway.
Signal probe
------------
'hf felica raw -p' streams the per-window envelope min and max instead of demodulated bits, so reading distance and coupling can be measured rather than
guessed. This is what told 'tag out of range' apart from 'demodulator not locking', which are otherwise identical from the ARM's point of view.
Measured on a RDV4, both cards previously unreadable:
FeliCa Standard RC-S830 (CJRC 0003): reader 4/4, info 4/4, 39 nodes discovered, dump complete in 2.0 s, 37/40 single polls.
FeliCa Standard RC-S962 (Octopus 8008): reader 10/10, 23 nodes discovered, dump complete in 1.5 s, 40/60 single polls. This one drives the envelope onto the bottom ADC rail; the matched filter reads it anyway.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
* .h include only the strict minimum for their own parsing
* this forces all files to include explicitment their needs and not count on far streched dependencies
* this helps Makefile to rebuild only the minimum
* according to this rule, most standalone .h are now gone
* big app.h is gone
* remove seldom __cplusplus, if c++ happens, everything will have to be done properly anyway
* all unrequired include were removed
* split common/ into common/ (client+arm) and common_arm/ (os+bootloader)
* bring zlib to common/
* bring stuff not really/not yet used in common back to armsrc/ or client/
* bring liblua into client/
* bring uart into client/
* move some portions of code around (dbprint, protocols,...)
* rename unused files into *_disabled.[ch] to make it explicit
* rename soft Uarts between 14a, 14b and iclass, so a standalone could use several without clash
* remove PrintAndLogDevice
* move deprecated-hid-flasher from client to tools
* Makefiles
* treat deps in armsrc/ as in client/
* client: stop on warning (-Werror), same as for armsrc/
Tested on:
* all standalone modes
* Linux
This is a new LF edge detection algorithm for the FPGA.
- It uses a low-pass IIR filter to clean the signal
(see https://fail0verflow.com/blog/2014/proxmark3-fpga-iir-filter.html)
- The algorithm is able to detect consecutive peaks in the same
direction
- It uses an envelope follower to dynamically adjust the peak thresholds
- The main threshold used in the envelope follower can be set from the ARM side
fpga/lf_edge_detect.v,
fpga/lp20khz_1MSa_iir_filter.v,
fpga/min_max_tracker.v: New file.
fpga/lo_edge_detect.v, fpga/fpga_lf.v: Modify accordingly.
armsrc/apps.h (FPGA_CMD_SET_USER_BYTE1,
FPGA_CMD_SET_EDGE_DETECT_THRESHOLD): New FPGA command.
fpga/fpga_lf.v: Modify accordingly/Add a 8bit user register.
fpga/fpga_lf.bit: Update accordingly.
fpga/tests: New directory for testbenches
fpga/tests/Makefile: New file. It compiles the testbenches
and runs all the tests by default (comparing with the golden output)
fpga/tests/tb_lp20khz_1MSa_iir_filter.v,
fpga/tests/tb_min_max_tracker.v,
fpga/tests/tb_lf_edge_detect.v: New testbenches
fpga/tests/plot_edgedetect.py: New script to plot the results from
the edge detection tests.
fpga/tests/tb_data: New directory for data and golden outputs
Retire rbt2c.pl, instead use objcopy to directly convert the .bit file into an .o that can be linked with the flash image
Rename armsrc/fpga.c to armsrc/fpgaloader.c (since there is now a new fpga.o, created from fpga.bit)
Remove fpgaimg.c from subversion, add fpga.bit
Instead of creating fpgaimage.elf and osimage.elf separately, now create a joined fullimage.elf
first (obsoleting ldscript-full), then extract only the fpga and os sections with objcopy
(This creates unspecific warnings about an empty segment, need to investigate)
Implement a rudimentary .bit parser in the firmware, use that to locate the bitstream in the new
fpgaimage (which is just a plain copy of the fpga.bit file) and send it to the FPGA
The code will check the format that's in flash and fall back to the legacy format
