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-rw-r--r--center_fw/src/main.c165
1 files changed, 47 insertions, 118 deletions
diff --git a/center_fw/src/main.c b/center_fw/src/main.c
index 4df1db5..53b6aae 100644
--- a/center_fw/src/main.c
+++ b/center_fw/src/main.c
@@ -16,10 +16,10 @@
*/
#include "global.h"
+#include "8b10b.h"
-uint16_t adc_data[192*2];
-
-const int nominal_period = 125*16*32/2;
+static uint16_t adc_data[64*2];
+static volatile struct state_8b10b_dec st_8b10b_dec;
static void quicksort(uint16_t *head, uint16_t *tail);
@@ -64,11 +64,13 @@ int main(void) {
NVIC_SetPriority(TIM1_CC_IRQn, 0);
*/
+ xfr_8b10b_reset((struct state_8b10b_dec *)&st_8b10b_dec);
+
TIM3->CR1 = TIM_CR1_ARPE;
TIM3->CR2 = (2<<TIM_CR2_MMS_Pos); /* Update event on TRGO */
TIM3->PSC = 0;
/* We sample 32 times per 1 kHz AC cycle, and use 32 times oversampling. */
- TIM3->ARR = 125*32; /* Output 64 MHz / 125 = 512 kHz signal */
+ TIM3->ARR = 125*16; /* Output 64 MHz / 125 = 512 kHz signal */
TIM3->CR1 |= TIM_CR1_CEN;
DMAMUX1[0].CCR = 5; /* ADC */
@@ -121,131 +123,58 @@ void TIM1_CC_IRQHandler(void) {
TIM1->SR &= ~TIM_SR_CC1IF;
}
*/
+static size_t received_symbols = 0;
+static int symbol_buf[32];
+static size_t received_bits = 0;
+static int16_t bit_buf[256];
+size_t adc_reduced_pos = 0;
+static uint8_t adc_reduced[4096];
void DMA1_Channel1_IRQHandler(void) {
- static int32_t bottom = -1;
- static int32_t top = -1;
+ static int sampling_phase = 0;
+ static int last_sample = 0;
+
+ uint16_t *buf = (DMA1->ISR & DMA_ISR_HTIF1) ? &adc_data[0] : &adc_data[COUNT_OF(adc_data)/2];
DMA1->IFCR = DMA_IFCR_CGIF1;
- int phase_correction = 0;
GPIOB->BSRR = (1<<7);
- uint16_t *data = DMA1->ISR & DMA_ISR_HTIF1 ? &adc_data[0] : &adc_data[192];
-
- if (bottom >= 0) {
- uint32_t amplitude = top - bottom;
- uint32_t middle = bottom + amplitude / 2;
-
- const uint32_t lower_thr = bottom + amplitude / 4;
- const uint32_t upper_thr = top - amplitude / 4;
- const uint32_t adc_clockdiv = 125 * 32;
-
- int num_edges = 0;
- int edge_indices[24];
-
- int state = 0;
- ssize_t run_start = -1;
- int last_v = -1;
- for (ssize_t i=0; i<192-1; i++) {
- uint32_t a = data[i], b = data[i+1];
-
- if (state == 0) {
- if (a < lower_thr && b > lower_thr) {
- state = 1;
- run_start = i+1;
- } else if (a > upper_thr && b < upper_thr) {
- state = -1;
- run_start = i+1;
- }
-
- } else if (state == 1) {
- if (b < a) {
- state = 0;
- } else if (a < upper_thr && b > upper_thr) {
- /* run from run_start (incl.) to i (incl.) */
- uint32_t v0 = data[run_start];
- int d = a - v0;
- int c = i - run_start;
- size_t intercept = run_start * adc_clockdiv + (middle - v0) * adc_clockdiv * c / d;
- if (num_edges < COUNT_OF(edge_indices)) {
- edge_indices[num_edges] = intercept;
- num_edges++;
- }
- state = 0;
- }
-
- } else if (state == -1) {
- if (b > a) {
- state = 0;
- } else if (a > lower_thr && b < lower_thr) {
- uint32_t v0 = data[run_start];
- int d = a - v0;
- int c = i - run_start;
- size_t intercept = run_start * adc_clockdiv + (middle - v0) * adc_clockdiv * c / d;
- if (num_edges < COUNT_OF(edge_indices)) {
- edge_indices[num_edges] = intercept;
- num_edges++;
- }
- state = 0;
- }
- }
+
+ const int threshold_adc_counts = 28500;
+ const int sample_per_baud = 16;
+
+ for (size_t i=0; i<COUNT_OF(adc_data)/2; i++) {
+ int sample = buf[i];
+
+ adc_reduced[adc_reduced_pos] = (sample & 0xffff)>>9;
+ if (adc_reduced_pos == 0) {
+ asm volatile ("bkpt");
}
- if (num_edges > 1) {
- const int approx_cycle = 32*16*125/2;
- int delta_avg = 0;
- for (size_t i=0; i<num_edges-1; i++) {
- int delta = edge_indices[i+1] - edge_indices[i];
- if (delta > approx_cycle/2 * 50) {
- asm volatile ("bkpt");
- }
- while (delta > approx_cycle/2) {
- delta -= approx_cycle;
- }
- delta_avg += delta;
- }
- delta_avg /= num_edges-1;
-
- int cycle = approx_cycle + delta_avg;
- int offset = 0;
- int phase_avg = 0;
- for (size_t i=0; i<num_edges; i++) {
- int remainder = edge_indices[i] - offset;
- while (remainder > cycle/2) {
- remainder -= cycle;
- offset += cycle;
- }
- phase_avg += remainder;
- }
- phase_avg /= num_edges;
- phase_correction = phase_avg >= 0 ? cycle/2 - phase_avg : cycle/2 + phase_avg;
- phase_correction /= 125 * 4;
-
- const int deadzone = 3;
- const int max_correction = 40;
- if (phase_correction < -deadzone || phase_correction > deadzone) {
- if (phase_correction < -max_correction) {
- phase_correction = -max_correction;
- } else if (phase_correction > max_correction) {
- phase_correction = max_correction;
- }
+ if ((last_sample <= threshold_adc_counts && sample >= threshold_adc_counts) ||
+ (last_sample >= threshold_adc_counts && sample <= threshold_adc_counts)){
+ sampling_phase = sample_per_baud / 4; /* /2 for half baud sampling point, /2 for sinusoidal edge shape */
+
+ } else if (sampling_phase == 0) {
+ int bit = sample < threshold_adc_counts;
+ adc_reduced[adc_reduced_pos] |= 0x80;
+
+ bit_buf[received_bits] = bit;
+ received_bits = (received_bits+1) % COUNT_OF(bit_buf);
+
+ int rc = xfr_8b10b_feed_bit((struct state_8b10b_dec *)&st_8b10b_dec, bit);
+ if (rc > -K_CODES_LAST) {
+ symbol_buf[received_symbols] = rc;
+ received_symbols = (received_symbols+1) % COUNT_OF(symbol_buf);
}
- }
- }
+ sampling_phase = sample_per_baud;
- const int discard = 5;
- const int keep = 32;
+ } else {
+ sampling_phase--;
+ }
- bottom = 0;
- top = 0;
- quicksort(data, &data[192-1]);
- for (size_t i=0; i<keep; i++) {
- bottom += data[discard + i];
- top += data[COUNT_OF(data)/2 - 1 - discard - i];
+ adc_reduced_pos = (adc_reduced_pos+1) % COUNT_OF(adc_reduced);
+ last_sample = sample;
}
- bottom /= keep;
- top /= keep;
-
- TIM3->ARR = 125*32 + phase_correction;
GPIOB->BRR = (1<<7);
}