fix(adc): workaround to fix adc continuous get less results on c3

components/esp_adc/adc_continuous.c

@@ -393,6 +393,11 @@ esp_err_t adc_continuous_stop(adc_continuous_handle_t handle)
     //stop ADC
     adc_hal_digi_stop(&handle->hal);
 
+#if ADC_LL_WORKAROUND_CLEAR_EOF_COUNTER
+    periph_module_reset(PERIPH_SARADC_MODULE);
+    adc_hal_digi_clr_eof();
+#endif
+
     adc_hal_digi_deinit(&handle->hal);
 
     if (handle->use_adc2) {

components/esp_adc/test_apps/adc/main/test_adc_driver.c

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -142,8 +142,6 @@ TEST_CASE("ADC oneshot fast work with ISR", "[adc_oneshot]")
 #define ADC_DRIVER_TEST_GET_DATA(p_data)        ((p_data)->type2.data)
 #endif
 
-#if !CONFIG_IDF_TARGET_ESP32C3 //TODO: DIG-270
-
 #define ADC_RESTART_TEST_SIZE   4096
 #define ADC_READ_TEST_COUNT     10
 
@@ -191,7 +189,6 @@ TEST_CASE("ADC continuous test after restarting", "[adc_continuous]")
     TEST_ESP_OK(adc_continuous_deinit(handle));
     free(result);
 }
-#endif //!CONFIG_IDF_TARGET_ESP32C3
 
 #if SOC_ADC_DIG_IIR_FILTER_SUPPORTED
 TEST_CASE("ADC filter exhausted allocation", "[adc_oneshot]")

components/hal/adc_hal.c

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2019-2023 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2019-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -358,3 +358,10 @@ void adc_hal_digi_stop(adc_hal_dma_ctx_t *hal)
     //disconnect DMA and peripheral
     adc_ll_digi_dma_disable();
 }
+
+#if ADC_LL_WORKAROUND_CLEAR_EOF_COUNTER
+void adc_hal_digi_clr_eof(void)
+{
+    adc_ll_digi_dma_clr_eof();
+}
+#endif

components/hal/esp32c3/include/hal/adc_ll.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2015-2021 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2015-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -56,6 +56,13 @@ extern "C" {
 #define ADC_LL_DEFAULT_CONV_LIMIT_EN      0
 #define ADC_LL_DEFAULT_CONV_LIMIT_NUM     10
 
+/**
+ * Workaround: on ESP32C3, the internal hardware counter that counts ADC samples will not be automatically cleared,
+ * and there is no dedicated register to manually clear it. (see section 3.2 of the errata document).
+ * Therefore, traverse from 0 to the value configured last time, so as to clear the ADC sample counter.
+ */
+#define ADC_LL_WORKAROUND_CLEAR_EOF_COUNTER            (1)
+
 /*---------------------------------------------------------------
                     PWDET (Power Detect)
 ---------------------------------------------------------------*/
@@ -437,6 +444,18 @@ static inline void adc_ll_digi_dma_set_eof_num(uint32_t num)
     HAL_FORCE_MODIFY_U32_REG_FIELD(APB_SARADC.dma_conf, apb_adc_eof_num, num);
 }
 
+/**
+ * Clear ADC sample counter of adc digital controller.
+ */
+static inline void adc_ll_digi_dma_clr_eof(void)
+{
+    uint32_t eof_num = HAL_FORCE_READ_U32_REG_FIELD(APB_SARADC.dma_conf, apb_adc_eof_num);
+    for (int i = 0; i <= eof_num; i++)
+    {
+        HAL_FORCE_MODIFY_U32_REG_FIELD(APB_SARADC.dma_conf, apb_adc_eof_num, i);
+    }
+}
+
 /**
  * Enable output data to DMA from adc digital controller.
  */

components/hal/include/hal/adc_hal.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -207,6 +207,13 @@ void adc_hal_digi_dis_intr(adc_hal_dma_ctx_t *hal, uint32_t mask);
  */
 void adc_hal_digi_stop(adc_hal_dma_ctx_t *hal);
 
+#if ADC_LL_WORKAROUND_CLEAR_EOF_COUNTER
+/**
+ * @brief Clear the ADC sample counter
+ */
+void adc_hal_digi_clr_eof(void);
+#endif
+
 #ifdef __cplusplus
 }
 #endif