unleashed-firmware/applications/lfrfid/helpers/decoder_ioprox.cpp

108 lines
2.9 KiB
C++

#include "decoder_ioprox.h"
#include <furi_hal.h>
#include <cli/cli.h>
#include <utility>
constexpr uint32_t clocks_in_us = 64;
constexpr uint32_t jitter_time_us = 20;
constexpr uint32_t min_time_us = 64;
constexpr uint32_t max_time_us = 80;
constexpr uint32_t baud_time_us = 500;
constexpr uint32_t min_time = (min_time_us - jitter_time_us) * clocks_in_us;
constexpr uint32_t mid_time = ((max_time_us - min_time_us) / 2 + min_time_us) * clocks_in_us;
constexpr uint32_t max_time = (max_time_us + jitter_time_us) * clocks_in_us;
constexpr uint32_t baud_time = baud_time_us * clocks_in_us;
bool DecoderIoProx::read(uint8_t* data, uint8_t data_size) {
bool result = false;
furi_assert(data_size >= 4);
if(ready) {
result = true;
ioprox.decode(raw_data, sizeof(raw_data), data, data_size);
ready = false;
}
return result;
}
void DecoderIoProx::process_front(bool is_rising_edge, uint32_t time) {
if(ready) {
return;
}
// Always track the time that's gone by.
current_period_duration += time;
demodulation_sample_duration += time;
// If a baud time has elapsed, we're at a sample point.
if(demodulation_sample_duration >= baud_time) {
// Start a new baud period...
demodulation_sample_duration = 0;
demodulated_value_invalid = false;
// ... and if we didn't have any baud errors, capture a sample.
if(!demodulated_value_invalid) {
store_data(current_demodulated_value);
}
}
//
// FSK demodulator.
//
// If this isn't a rising edge, this isn't a pulse of interest.
// We're done.
if(!is_rising_edge) {
return;
}
bool is_valid_low = (current_period_duration > min_time) &&
(current_period_duration <= mid_time);
bool is_valid_high = (current_period_duration > mid_time) &&
(current_period_duration < max_time);
// If this is between the minimum and our threshold, this is a logical 0.
if(is_valid_low) {
current_demodulated_value = false;
}
// Otherwise, if between our threshold and the max time, it's a logical 1.
else if(is_valid_high) {
current_demodulated_value = true;
}
// Otherwise, invalidate this sample.
else {
demodulated_value_invalid = true;
}
// We're starting a new period; track that.
current_period_duration = 0;
}
DecoderIoProx::DecoderIoProx() {
reset_state();
}
void DecoderIoProx::store_data(bool data) {
for(int i = 0; i < 7; ++i) {
raw_data[i] = (raw_data[i] << 1) | ((raw_data[i + 1] >> 7) & 1);
}
raw_data[7] = (raw_data[7] << 1) | data;
if(ioprox.can_be_decoded(raw_data, sizeof(raw_data))) {
ready = true;
}
}
void DecoderIoProx::reset_state() {
current_demodulated_value = false;
demodulated_value_invalid = false;
current_period_duration = 0;
demodulation_sample_duration = 0;
ready = false;
}