Add sampling time configuration to ADC module as requested in issue #23.

zephyr/modules/owntech_adc_driver/zephyr/public_api/adc.c

@@ -18,7 +18,7 @@
  */
 
 /*
- * @date   2024
+ * @date   2025
  *
  * @author Clément Foucher <clement.foucher@laas.fr>
  */
@@ -45,10 +45,11 @@
  *  Local variables
  */
 
-static adc_ev_src_t adc_trigger_sources[NUMBER_OF_ADCS]    = {0};
-static uint32_t     adc_discontinuous_mode[NUMBER_OF_ADCS] = {0};
-static uint32_t     enabled_channels_count[NUMBER_OF_ADCS] = {0};
-static bool         enable_dma[NUMBER_OF_ADCS]             = {0};
+static adc_ev_src_t        adc_trigger_sources[NUMBER_OF_ADCS]    = {0};
+static uint32_t            adc_discontinuous_mode[NUMBER_OF_ADCS] = {0};
+static adc_sampling_time_t adc_sampling_times[NUMBER_OF_ADCS]     = {0};
+static uint32_t            enabled_channels_count[NUMBER_OF_ADCS] = {0};
+static bool                enable_dma[NUMBER_OF_ADCS]             = {0};
 
 static uint32_t
 		enabled_channels[NUMBER_OF_ADCS][NUMBER_OF_CHANNELS_PER_ADC] = {0};
@@ -75,6 +76,15 @@ void adc_configure_discontinuous_mode(uint8_t adc_number,
 	adc_discontinuous_mode[adc_number-1] = discontinuous_count;
 }
 
+void adc_configure_sampling_time(uint8_t adc_number,
+                                 adc_sampling_time_t sampling_time)
+{
+	if ( (adc_number == 0) || (adc_number > NUMBER_OF_ADCS) )
+		return;
+
+	adc_sampling_times[adc_number-1] = sampling_time;
+}
+
 void adc_add_channel(uint8_t adc_number, uint8_t channel)
 {
 	if ( (adc_number == 0) || (adc_number > NUMBER_OF_ADCS) )
@@ -156,6 +166,13 @@ void adc_start()
 	for (uint8_t adc_num = 1 ; adc_num <= NUMBER_OF_ADCS ; adc_num++)
 	{
 		uint8_t adc_index = adc_num-1;
+
+		adc_sampling_time_t sampling_time = adc_sampling_times[adc_index];
+		if (sampling_time == adc_st_default)
+		{
+			sampling_time = adc_st_294ns;
+		}
+
 		if (enabled_channels_count[adc_index] > 0)
 		{
 			for (int channel_index = 0;
@@ -165,10 +182,15 @@ void adc_start()
 				if (enabled_channels[adc_index][channel_index] == 0)
 					break;
 
-				adc_core_configure_channel(
+				adc_core_set_channel_rank(
 					adc_num,
 					enabled_channels[adc_index][channel_index],
 					channel_index+1);
+
+				adc_core_set_channel_sampling_time(
+					adc_num,
+					enabled_channels[adc_index][channel_index],
+					sampling_time);
 			}
 		}
 	}

zephyr/modules/owntech_adc_driver/zephyr/public_api/adc.h

@@ -18,7 +18,7 @@
  */
 
 /*
- * @date   2024
+ * @date   2025
  *
  * @author Clément Foucher <clement.foucher@laas.fr>
  *
@@ -42,39 +42,14 @@
 #include <stdint.h>
 #include <stdbool.h>
 
+/* Owntech */
+#include "adc_enums.h"
+
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-
-/**
- *  Public enums
- */
-
-/**
- * @brief Defines types of hrtim events to which the ADC connects: 
- *        
- * - software - software events
- *        
- * - `hrtim_ev1` to `hrtim_ev9` - hrtim driven events
- * 
- */
-typedef enum
-{
-	software  = 0,
-	hrtim_ev1 = 1,
-	hrtim_ev2 = 2,
-	hrtim_ev3 = 3,
-	hrtim_ev4 = 4,
-	hrtim_ev5 = 5,
-	hrtim_ev6 = 6,
-	hrtim_ev7 = 7,
-	hrtim_ev8 = 8,
-	hrtim_ev9 = 9
-} adc_ev_src_t;
-
-
 /* Public API */
 
 /**
@@ -104,6 +79,22 @@ void adc_configure_trigger_source(uint8_t adc_number,
 void adc_configure_discontinuous_mode(uint8_t adc_number,
 									  uint32_t discontinuous_count);
 
+/**
+ * @brief Registers the samping time to use for an ADC.
+ *
+ *        This will only be applied when ADC is started.
+ *        If ADC is already started, it must be stopped
+ *        then started again.
+ *
+ *        Default samping time is 294 ns.
+ *
+ * @param adc_number Number of the ADC to configure.
+ * @param discontinuous_count Number of channels to acquire on each
+ *        trigger event. 0 to disable discontinuous mode (default).
+ */
+void adc_configure_sampling_time(uint8_t adc_number,
+                                 adc_sampling_time_t sampling_time);
+
 /**
  * @brief Adds a channel to the list of channels to be acquired
  *        for an ADC.

zephyr/modules/owntech_adc_driver/zephyr/public_api/adc_enums.h

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2025-present LAAS-CNRS
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU Lesser General Public License as published by
+ *   the Free Software Foundation, either version 2.1 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU Lesser General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Lesser General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: LGPL-2.1
+ */
+
+/*
+ * @date   2025
+ *
+ * @author Clément Foucher <clement.foucher@laas.fr>
+ */
+
+#ifndef ADC_ENUMS_H_
+#define ADC_ENUMS_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Defines types of hrtim events to which the ADC connects:
+ *
+ * - software - software events
+ *
+ * - `hrtim_ev1` to `hrtim_ev9` - hrtim driven events
+ *
+ */
+typedef enum
+{
+	software  = 0,
+	hrtim_ev1 = 1,
+	hrtim_ev2 = 2,
+	hrtim_ev3 = 3,
+	hrtim_ev4 = 4,
+	hrtim_ev5 = 5,
+	hrtim_ev6 = 6,
+	hrtim_ev7 = 7,
+	hrtim_ev8 = 8,
+	hrtim_ev9 = 9
+} adc_ev_src_t;
+
+/**
+ * @brief Defines the sampling time for the ADC.
+ * The clock source is 170 MHz, and ADC prescaler is set
+ * to 4, which makes the ADC clock 42.5 MHz.
+ * Cycle duration is thus ≈ 23.5 ns.
+ *
+ * Available sampling times (in cycles) are:
+ * - 2.5   => 58.75 ns
+ * - 6.5   => 152.75 ns
+ * - 12.5  => 293.75 ns
+ * - 24.5  => 575.75 ns
+ * - 47.5  => 1116.25 ns
+ * - 92.5  => 2173.75 ns
+ * - 247.5 => 5816.25 ns
+ * - 640.5 => 15051.75 ns
+ *
+ * Let's round to the ns here.
+ */
+typedef enum
+{
+	adc_st_default = 0,
+	adc_st_59ns,
+	adc_st_153ns,
+	adc_st_294ns,
+	adc_st_576ns,
+	adc_st_1116ns,
+	adc_st_2174ns,
+	adc_st_5817ns,
+	adc_st_15052ns
+} adc_sampling_time_t;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ADC_ENUMS_H_ */