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fix-LF-emulation #221

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fix-LF-emulation #221

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b655c73
fix LF emulation; make continuous sending ID; increase field sensing …
Dmytro-Kli Aug 5, 2024
6145f5c
fix typo
Dmytro-Kli Aug 6, 2024
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12 changes: 10 additions & 2 deletions firmware/application/src/rfid/nfctag/lf/lf_tag_em.c
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Original file line number Diff line number Diff line change
Expand Up @@ -201,7 +201,8 @@ uint64_t em410x_id_to_memory64(uint8_t id[5]) {
*/
bool lf_is_field_exists(void) {
nrf_drv_lpcomp_enable();
bsp_delay_us(20); // Display for a period of time and sampling to avoid misjudgment
// With 20ms of delay CU was not able to detect the field of my reader after waking up.
bsp_delay_us(30); // Display for a period of time and sampling to avoid misjudgment
nrf_lpcomp_task_trigger(NRF_LPCOMP_TASK_SAMPLE); //Trigger a sampling
return nrf_lpcomp_result_get() == 1; //Determine the sampling results of the LF field status
}
Expand Down Expand Up @@ -261,7 +262,14 @@ void timer_ce_handler(nrf_timer_event_t event_type, void *p_context) {
if (m_is_send_first_edge == true) { // The first edge of the next sends next time
if (++m_bit_send_position >= LF_125KHZ_EM410X_BIT_SIZE) {
m_bit_send_position = 0; // The broadcast is successful once, and the BIT position is zero
if (++m_send_id_count >= LF_125KHZ_BROADCAST_MAX) {
/* The main part of the idea. The original EM4100 tag continuously sends its ID.
* The root problem, in my point of view, was that CU started to "feel" the field too far to be able to modulate it deep enough,
* and 3 times (LF_125KHZ_BROADCAST_MAX) of repeating takes only about 100ms, CU is still not close enough to the reader.
* That is why the emulation worked only if the CU moved past the reader quickly (fly by).*/
if(!lf_is_field_exists()){
m_send_id_count++;
}
if (m_send_id_count >= LF_125KHZ_BROADCAST_MAX) {
m_send_id_count = 0; //The number of broadcasts reaches the upper limit, re -identifies the status of the field and re -statistically count the number of broadcast times
}
}
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3 changes: 2 additions & 1 deletion firmware/application/src/rfid/nfctag/lf/lf_tag_em.h
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Expand Up @@ -11,7 +11,8 @@
* The definition of the packaging tool macro only needs to be modulated 0 and 1
*/
#define LF_125KHZ_EM410X_BIT_SIZE 64
#define LF_125KHZ_BROADCAST_MAX 3 // 32.768ms once, about 31 times in one second
// Have decided to increase the period of field sensing in this way
#define LF_125KHZ_BROADCAST_MAX 10 // 32.768ms once, about 31 times in one second
#define LF_125KHZ_EM410X_BIT_CLOCK 256
#define LF_EM410X_TAG_ID_SIZE 5

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