esp32: Update ADC driver update to the new esp_adc API.HEADmaster

This commit updates the ADC to use the new driver `esp_adc/adc_oneshot.h`.

There are several errata notes about not being able to change the bit-width
of the ADCs certain chips.  The only chip that can switch resolution to a
lower one is the normal ESP32.  ESP32 C2 and S3 are stuck at 12 bits, while
S2 is at 13 bits.

On the S2, you can change the resolution, but it has no effect on the
resolution, rather, it prevents attenuation from working at all!

The resolution is set to the maximum possible for each SoC, with the ESP32
being the only one not throwing errors when trying to set the bit-width to
9, 10, 11 or 12 bits using `ADC.width(bits)`.

Signed-off-by: Damian Nowacki (purewack) bobimaster15@gmail.com

1 files changed, 42 insertions, 52 deletions

diff --git a/ports/esp32/adc.c b/ports/esp32/adc.c
index 83af6dce0b..d0e5e81330 100644
--- a/ports/esp32/adc.c
+++ b/ports/esp32/adc.c
@@ -26,83 +26,73 @@
  */
 
 #include "py/mphal.h"
+#include "py/mperrno.h"
 #include "adc.h"
-#include "driver/adc.h"
+#include "esp_adc/adc_oneshot.h"
 #include "esp_adc/adc_cali_scheme.h"
 
-#define DEFAULT_VREF 1100
+static esp_err_t ensure_adc_calibration(machine_adc_block_obj_t *self, adc_atten_t atten);
 
-void madcblock_bits_helper(machine_adc_block_obj_t *self, mp_int_t bits) {
-    if (bits < SOC_ADC_RTC_MIN_BITWIDTH && bits > SOC_ADC_RTC_MAX_BITWIDTH) {
-        // Invalid value for the current chip, raise exception in the switch below.
-        bits = -1;
+void adc_is_init_guard(machine_adc_block_obj_t *self) {
+    if (!self->handle) {
+        mp_raise_OSError(MP_EPERM);
     }
-    switch (bits) {
-        case 9:
-            self->width = ADC_BITWIDTH_9;
-            break;
-        case 10:
-            self->width = ADC_BITWIDTH_10;
-            break;
-        case 11:
-            self->width = ADC_BITWIDTH_11;
-            break;
-        case 12:
-            self->width = ADC_BITWIDTH_12;
-            break;
-        case 13:
-            self->width = ADC_BITWIDTH_13;
-            break;
-        default:
-            mp_raise_ValueError(MP_ERROR_TEXT("invalid bits"));
-    }
-    self->bits = bits;
+}
 
-    if (self->unit_id == ADC_UNIT_1) {
-        adc1_config_width(self->width);
-    }
+esp_err_t apply_self_adc_channel_atten(const machine_adc_obj_t *self, uint8_t atten) {
+    adc_is_init_guard(self->block);
+
+    adc_oneshot_chan_cfg_t config = {
+        .atten = atten,
+        .bitwidth = self->block->bitwidth,
+    };
+    esp_err_t ret = adc_oneshot_config_channel(self->block->handle, self->channel_id, &config);
+    return ret;
 }
 
 mp_int_t madcblock_read_helper(machine_adc_block_obj_t *self, adc_channel_t channel_id) {
-    int raw = 0;
-    if (self->unit_id == ADC_UNIT_1) {
-        raw = adc1_get_raw(channel_id);
-    } else {
-        #if (SOC_ADC_PERIPH_NUM >= 2)
-        check_esp_err(adc2_get_raw(channel_id, self->width, &raw));
-        #endif
-    }
-    return raw;
+    adc_is_init_guard(self);
+
+    int reading = 0;
+    adc_oneshot_read(self->handle, channel_id, &reading);
+    return reading;
+}
+
+/*
+During testing, it turned out that the function `adc_cali_raw_to_voltage` does not account for the lower resolution,
+instead it expects the full resolution value as an argument, hence the scaling applied here
+*/
+mp_int_t madcblock_read_uv_helper(machine_adc_block_obj_t *self, adc_channel_t channel_id, adc_atten_t atten) {
+    int raw = madcblock_read_helper(self, channel_id);
+    int uv = 0;
+
+    check_esp_err(ensure_adc_calibration(self, atten));
+    check_esp_err(adc_cali_raw_to_voltage(self->calib[atten], (raw << (ADC_WIDTH_MAX - self->bitwidth)), &uv));
+    return (mp_int_t)uv * 1000;
 }
 
 static esp_err_t ensure_adc_calibration(machine_adc_block_obj_t *self, adc_atten_t atten) {
-    if (self->handle[atten] != NULL) {
+    if (self->calib[atten] != NULL) {
         return ESP_OK;
     }
 
+    esp_err_t ret = ESP_OK;
+
     #if ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED
     adc_cali_curve_fitting_config_t cali_config = {
         .unit_id = self->unit_id,
         .atten = atten,
-        .bitwidth = self->width,
+        .bitwidth = self->bitwidth,
     };
-    return adc_cali_create_scheme_curve_fitting(&cali_config, &self->handle[atten]);
+    ret = adc_cali_create_scheme_curve_fitting(&cali_config, &self->calib[atten]);
     #else
     adc_cali_line_fitting_config_t cali_config = {
         .unit_id = self->unit_id,
         .atten = atten,
-        .bitwidth = self->width,
+        .bitwidth = self->bitwidth,
     };
-    return adc_cali_create_scheme_line_fitting(&cali_config, &self->handle[atten]);
+    ret = adc_cali_create_scheme_line_fitting(&cali_config, &self->calib[atten]);
     #endif
-}
 
-mp_int_t madcblock_read_uv_helper(machine_adc_block_obj_t *self, adc_channel_t channel_id, adc_atten_t atten) {
-    int raw = madcblock_read_helper(self, channel_id);
-    int uv;
-
-    check_esp_err(ensure_adc_calibration(self, atten));
-    check_esp_err(adc_cali_raw_to_voltage(self->handle[atten], raw, &uv));
-
-    return (mp_int_t)uv * 1000;
+    return ret;
 }