ADC 데이터 샘플 간 간격 줄이기

src/drivers/echo_adc/echo_adc.c

@@ -8,6 +8,7 @@
 #include <zephyr/devicetree.h>
 #include <zephyr/sys/util.h>
 #include <nrfx_spim.h>
+#include <hal/nrf_spim.h>
 #include <errno.h>
 
 #include "echo_adc.h"
@@ -30,6 +31,11 @@ static nrfx_spim_t echo_spim = NRFX_SPIM_INSTANCE(NRF_SPIM3);
 static bool echo_adc_initialized;
 static uint8_t raw_capture[ECHO_ADC_MAX_SAMPLES * 2];
 
+static NRF_GPIO_Type *gpio_reg_for_spec(const struct gpio_dt_spec *spec)
+{
+	return (spec->port == DEVICE_DT_GET(DT_NODELABEL(gpio1))) ? NRF_P1 : NRF_P0;
+}
+
 static uint32_t gpio_abs_pin(const struct gpio_dt_spec *spec)
 {
 	uint32_t port = (spec->port == DEVICE_DT_GET(DT_NODELABEL(gpio1))) ? 1U : 0U;
@@ -50,6 +56,79 @@ static int echo_adc_transfer_rx(uint8_t *buf, size_t len)
 	return 0;
 }
 
+static void echo_adc_unpack_samples(uint16_t *samples, uint16_t num_samples)
+{
+	for (uint16_t i = 0; i < num_samples; i++)
+	{
+		uint16_t raw16 = ((uint16_t)raw_capture[i * 2U] << 8) |
+				 (uint16_t)raw_capture[i * 2U + 1U];
+		samples[i] = (raw16 >> 1) & 0x0FFF;
+	}
+}
+
+static bool echo_adc_samples_all_zero(const uint16_t *samples, uint16_t num_samples)
+{
+	for (uint16_t i = 0; i < num_samples; i++)
+	{
+		if (samples[i] != 0U)
+		{
+			return false;
+		}
+	}
+
+	return true;
+}
+
+static int echo_adc_capture_slow(uint16_t *samples, uint16_t num_samples)
+{
+	for (uint16_t i = 0; i < num_samples; i++)
+	{
+		int err = echo_adc_transfer_rx(&raw_capture[i * 2U], 2U);
+		if (err)
+		{
+			return err;
+		}
+	}
+
+	echo_adc_unpack_samples(samples, num_samples);
+	return 0;
+}
+
+static int echo_adc_capture_fast(uint16_t *samples, uint16_t num_samples)
+{
+	NRF_SPIM_Type *spim = echo_spim.p_reg;
+	NRF_GPIO_Type *cs_port = gpio_reg_for_spec(&echo_cs);
+	uint32_t cs_mask = BIT(echo_cs.pin);
+
+	nrf_spim_enable(spim);
+	spim->RXD.MAXCNT = 2U;
+
+	for (uint16_t i = 0; i < num_samples; i++)
+	{
+		cs_port->OUTCLR = cs_mask;
+		spim->RXD.PTR = (uint32_t)&raw_capture[i * 2U];
+		spim->EVENTS_END = 0;
+		spim->TASKS_START = 1;
+
+		uint32_t timeout = 10000U;
+		while (!spim->EVENTS_END && (timeout > 0U))
+		{
+			timeout--;
+		}
+
+		cs_port->OUTSET = cs_mask;
+
+		if (timeout == 0U)
+		{
+			DBG_PRINTF("[ECHO] fast capture timeout\r\n");
+			return -ETIMEDOUT;
+		}
+	}
+
+	echo_adc_unpack_samples(samples, num_samples);
+	return 0;
+}
+
 int echo_adc_init(void)
 {
 	if (echo_adc_initialized || nrfx_spim_init_check(&echo_spim))
@@ -124,22 +203,12 @@ int echo_adc_capture(uint16_t *samples, uint16_t num_samples)
 		return err;
 	}
 
-	for (uint16_t i = 0; i < num_samples; i++)
+	err = echo_adc_capture_fast(samples, num_samples);
+	if ((err == 0) && !echo_adc_samples_all_zero(samples, num_samples))
 	{
-		/*
-		 * Keep the framing that matched the old firmware behavior:
-		 * one 16-clock / 2-byte SPI frame per sample.
-		 */
-		err = echo_adc_transfer_rx(&raw_capture[i * 2U], 2U);
-		if (err)
-		{
-			return err;
-		}
-
-		uint16_t raw16 = ((uint16_t)raw_capture[i * 2U] << 8) |
-				 (uint16_t)raw_capture[i * 2U + 1U];
-		samples[i] = (raw16 >> 1) & 0x0FFF;
+		return 0;
 	}
 
-	return 0;
+	DBG_PRINTF("[ECHO] fast capture fallback err=%d\r\n", err);
+	return echo_adc_capture_slow(samples, num_samples);
 }