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Fix ASK CTS timing and framing

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kormax
2026-06-29 23:11:57 +03:00
parent ae9a503280
commit e9fe7867ca
1 changed files with 19 additions and 2 deletions
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armsrc/iso14443b.c
+19 -2
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@@ -185,6 +185,8 @@
# define ISO14B_BLOCK_SIZE 4
#endif
#define CTS512B_POWER_ON_DELAY_US 500
// 4sample
#define SEND4STUFFBIT(x) tosend_stuffbit(!(x));tosend_stuffbit(!(x));tosend_stuffbit(!(x));tosend_stuffbit(!(x));
@@ -534,6 +536,7 @@ static struct {
uint16_t len;
int sumI;
int sumQ;
bool saw_sof;
} Demod;
// Clear out the state of the "UART" that receives from the tag.
@@ -546,6 +549,7 @@ static void Demod14bReset(void) {
Demod.len = 0;
Demod.sumI = 0;
Demod.sumQ = 0;
Demod.saw_sof = false;
}
static void Demod14bInit(uint8_t *data, uint16_t max_len) {
@@ -1240,6 +1244,13 @@ static RAMFUNC int Handle14443bSamplesFromTag(int ci, int cq) {
break;
}
case DEMOD_AWAITING_START_BIT: {
// CTS tag responses have no SOF/EOF; the frame ends when the tag
// stops load-modulating after the data bytes.
if (Demod.saw_sof == false && Demod.len > 0 && AMPLITUDE(ci, cq) < SUBCARRIER_DETECT_THRESHOLD) {
LED_C_OFF();
return true;
}
Demod.posCount++;
MAKE_SOFT_DECISION();
if (v > 0) {
@@ -1271,6 +1282,7 @@ static RAMFUNC int Handle14443bSamplesFromTag(int ci, int cq) {
Demod.posCount = 0;
Demod.bitCount = 0;
Demod.len = 0;
Demod.saw_sof = true;
Demod.state = DEMOD_AWAITING_START_BIT;
}
} else {
@@ -1557,6 +1569,10 @@ static void TransmitFor14443b_AsReader(uint32_t *start_time) {
while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY)) {};
}
static uint32_t ToSendBitCount(const tosend_t *ts) {
return (ts->max < 0) ? 0 : ((uint32_t)ts->max * 8U) + ts->bit;
}
//-----------------------------------------------------------------------------
// Code a layer 2 command (string of octets, including CRC) into ToSend[],
// so that it is ready to transmit to the tag using TransmitFor14443b().
@@ -1639,7 +1655,7 @@ void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len, uint32_t *start_
// eof_time in ssp clocks, but bits was added here!
// *eof_time = *start_time + (10 * ts->max) + 10 + 2 + 10;
*eof_time = *start_time + HF14_ETU_TO_SSP(8 * ts->max);
*eof_time = *start_time + HF14_ETU_TO_SSP(ToSendBitCount(ts));
LogTrace(cmd, len, *start_time, *eof_time, NULL, true);
}
@@ -1783,7 +1799,8 @@ static int iso14443b_select_cts_card(iso14b_cts_card_select_t *card) {
uint8_t r[8] = { 0x00 };
uint32_t start_time = 0;
// CTS512B accepts the first reader frame 500 us after RF power-on.
uint32_t start_time = US_TO_SSP(CTS512B_POWER_ON_DELAY_US);
uint32_t eof_time = 0;
CodeAndTransmit14443bAsReader(cmdINIT, sizeof(cmdINIT), &start_time, &eof_time, true);