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nfc_tag_14a_event_callback(): Fixes wrong reported length when sniffing #449

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nfc_tag_14a_event_callback(): Fixes wrong reported length when sniffing #449

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c3b08be
blk_num is unused, which caused build to fail.
DidierA Jun 18, 2026
2239acd
nfc_tag_14a_event_callback: remove wrong parity bit computation, whic…
DidierA Jun 18, 2026
3cba53c
update CHANGELOG.md
DidierA Jun 18, 2026
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file.
This project uses the changelog in accordance with [keepchangelog](http://keepachangelog.com/). Please use this to write notable changes, which is not the same as git commit log...

## [unreleased][unreleased]
- Fix wrong data reported by hf 14a sniff on frames containing more than 7 parity bits (@DidierA)
- Added Jablotron LF protocol support: read, emulate and T55xx clone (@midlan)
- Added IDTECK LF protocol support: tag emulation (PSK1 RF/32) and T55xx clone. No reader path yet; PSK demodulation on the envelope-only receive chain is left for a follow-up.
- Added PAC/Stanley LF protocol support: read, emulate and T55xx clone (@kevihiiin, @danieltwagner)
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3 changes: 0 additions & 3 deletions firmware/application/src/app_cmd.c
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Expand Up @@ -2502,14 +2502,12 @@ static data_frame_tx_t *cmd_processor_hf14a_4_reader_apdu(uint16_t cmd, uint16_t
}

/* Copy data portion (strip PCB + CRC), then handle chaining */
uint8_t blk_num = 0;
uint8_t resp_pcb = resp_buf[0];
uint8_t dlen = resp_bytes - 3; /* subtract PCB(1) + CRC(2) */
if (dlen > 0 && resp_chain_len + dlen < sizeof(resp_chain)) {
memcpy(&resp_chain[resp_chain_len], &resp_buf[1], dlen);
resp_chain_len += dlen;
}
blk_num ^= 1;

/* ISO14443-4 chaining: PCB bit5 (0x20) set means more blocks follow */
while (resp_pcb & 0x20) {
Expand All @@ -2532,7 +2530,6 @@ static data_frame_tx_t *cmd_processor_hf14a_4_reader_apdu(uint16_t cmd, uint16_t
memcpy(&resp_chain[resp_chain_len], &resp_buf[1], dlen);
resp_chain_len += dlen;
}
blk_num ^= 1;
}

return data_frame_make(cmd, STATUS_HF_TAG_OK, resp_chain_len, resp_chain);
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9 changes: 2 additions & 7 deletions firmware/application/src/rfid/nfctag/hf/nfc_14a.c
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Expand Up @@ -682,13 +682,8 @@ void nfc_tag_14a_event_callback(nrfx_nfct_evt_t const *p_event) {
uint32_t amt = NRF_NFCT->TXD.AMOUNT;
uint16_t tx_bytes = (amt >> NFCT_TXD_AMOUNT_TXDATABYTES_Pos)
& (NFCT_TXD_AMOUNT_TXDATABYTES_Msk >> NFCT_TXD_AMOUNT_TXDATABYTES_Pos);
uint16_t tx_bits_rem = (amt >> NFCT_TXD_AMOUNT_TXDATABITS_Pos)
& (NFCT_TXD_AMOUNT_TXDATABITS_Msk >> NFCT_TXD_AMOUNT_TXDATABITS_Pos);
uint16_t tx_bits = (tx_bits_rem > 0)
? ((tx_bytes - 1) * 8 + tx_bits_rem)
: (tx_bytes * 8);
if (tx_bits > 0 && tx_bytes <= MAX_NFC_TX_BUFFER_SIZE) {
m_tx_sniff_cb(m_nfc_tx_buffer, tx_bits);
if (amt > 0 && tx_bytes <= MAX_NFC_TX_BUFFER_SIZE) {
m_tx_sniff_cb(m_nfc_tx_buffer, amt);
}
}
break;
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