Merge branch 'feat/ulp_adc_multi_channel' into 'master'

feat(ulp): add multi-channel ADC init for ULP

Closes IDFGH-9831 and IDF-15815

See merge request espressif/esp-idf!49671

components/ulp/test_apps/ulp_riscv/main/test_ulp_riscv.c

@@ -471,6 +471,28 @@ TEST_CASE("ULP ADC can init-deinit-init", "[ulp]")
     TEST_ASSERT_EQUAL(ESP_OK, ulp_adc_deinit());
 }
 
+TEST_CASE("ULP ADC can init multiple channels", "[ulp]")
+{
+    /* Initialize the ADC unit and configure the first channel */
+    ulp_adc_cfg_t riscv_adc_cfg = {
+        .adc_n    = ADC_UNIT,
+        .channel  = ADC_CHANNEL_5,
+        .width    = WIDTH,
+        .atten    = ADC_ATTEN_DB_2_5,
+        .ulp_mode = ADC_ULP_MODE_FSM,
+    };
+    TEST_ASSERT_EQUAL(ESP_OK, ulp_adc_init(&riscv_adc_cfg));
+
+    /* Configure an additional channel on the same ADC unit */
+    ulp_adc_chan_cfg_t chan_cfg = {
+        .atten    = ADC_ATTEN_DB_12,
+        .bitwidth = WIDTH,
+    };
+    TEST_ASSERT_EQUAL(ESP_OK, ulp_adc_config_channel(ADC_UNIT, ADC_CHANNEL_6, &chan_cfg));
+
+    TEST_ASSERT_EQUAL(ESP_OK, ulp_adc_deinit());
+}
+
 TEST_CASE("Test ULP RISCV delay", "[ulp]")
 {
     int64_t start, diff;

components/ulp/ulp_common/include/ulp_adc.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2026 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -8,6 +8,7 @@
 
 #include "hal/adc_types.h"
 #include "esp_err.h"
+#include "esp_adc/adc_oneshot.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -21,14 +22,42 @@ typedef struct {
     adc_ulp_mode_t ulp_mode; // ADC ULP Mode
 } ulp_adc_cfg_t;      // ULP FSM ADC configuration parameters
 
+/**
+ * @brief ULP ADC channel configuration parameters
+ */
+typedef adc_oneshot_chan_cfg_t ulp_adc_chan_cfg_t;
+
 /**
  * @brief Initialize and calibrate the ADC for use by ULP FSM
  *
+ * @note Initializes the ADC unit for ULP use and configures the channel
+ *       specified in cfg->channel. To monitor multiple channels, call
+ *       ulp_adc_config_channel() afterwards to configure additional channels.
+ *
  * @param cfg           Configuration parameters
  * @return esp_err_t    ESP_OK for successful.
  */
 esp_err_t ulp_adc_init(const ulp_adc_cfg_t *cfg);
 
+/**
+ * @brief Configure and calibrate an additional ADC channel for use by ULP
+ *
+ * Configures a channel on an ADC unit that has already been initialized by
+ * ulp_adc_init(). This can be called multiple times to configure multiple
+ * channels on the same ADC unit.
+ *
+ * @note HW calibration parameters are stored per attenuation, but only one set
+ *       is active in the ADC unit at a time. If channels use different
+ *       attenuations, readings on channels whose attenuation differs from the
+ *       last configured one may be less accurate.
+ *
+ * @param adc_n         ADC unit (must already be initialized via ulp_adc_init())
+ * @param channel       ADC channel to configure
+ * @param chan_cfg      Channel configuration (attenuation and bit width)
+ * @return esp_err_t    ESP_OK for successful.
+ */
+esp_err_t ulp_adc_config_channel(adc_unit_t adc_n, adc_channel_t channel, const ulp_adc_chan_cfg_t *chan_cfg);
+
 /**
  * @brief Deinitialize ADC after use with ULP, allowing it to be reclaimed
  *

components/ulp/ulp_common/ulp_adc.c

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2022-2025 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2026 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -17,6 +17,27 @@
 static const char *TAG = "ulp_adc";
 static adc_oneshot_unit_handle_t s_adc_handle = NULL;
 
+esp_err_t ulp_adc_config_channel(adc_unit_t adc_n, adc_channel_t channel, const ulp_adc_chan_cfg_t *chan_cfg)
+{
+    esp_err_t ret = ESP_OK;
+
+    ESP_RETURN_ON_FALSE(chan_cfg, ESP_ERR_INVALID_ARG, TAG, "chan_cfg == NULL");
+    ESP_RETURN_ON_FALSE(s_adc_handle, ESP_ERR_INVALID_STATE, TAG, "ADC unit not initialized");
+
+    //-------------ADC Config---------------//
+    ret = adc_oneshot_config_channel(s_adc_handle, channel, chan_cfg);
+    if (ret != ESP_OK) {
+        return ret;
+    }
+
+    //Calibrate the ADC
+#if SOC_ADC_CALIBRATION_V1_SUPPORTED
+    adc_set_hw_calibration_code(adc_n, chan_cfg->atten);
+#endif
+
+    return ret;
+}
+
 esp_err_t ulp_adc_init(const ulp_adc_cfg_t *cfg)
 {
     esp_err_t ret = ESP_OK;
@@ -47,6 +68,8 @@ esp_err_t ulp_adc_init(const ulp_adc_cfg_t *cfg)
     };
     ret = adc_oneshot_config_channel(s_adc_handle, cfg->channel, &config);
     if (ret != ESP_OK) {
+        adc_oneshot_del_unit(s_adc_handle);
+        s_adc_handle = NULL;
         return ret;
     }
 

components/ulp/ulp_riscv/ulp_core/ulp_riscv_adc.c

@@ -12,6 +12,9 @@ int32_t ulp_riscv_adc_read_channel(adc_unit_t adc_n, int channel)
     adc_oneshot_ll_clear_event(event);
     adc_oneshot_ll_disable_all_unit();
     adc_oneshot_ll_enable(adc_n);
+    /* Force SW control of the channel bitmap; deep-sleep entry can clear it, which would
+     * otherwise make the channel selection below take no effect. */
+    adc_ll_set_controller(adc_n, ADC_LL_CTRL_RTC);
     adc_oneshot_ll_set_channel(adc_n, channel);
 
     adc_oneshot_ll_start(adc_n);