feat(keyboard): Add ble battery level report

Author: Deadline039

examples/keyboard/components/esp32_s3_kbd_kit/include/bsp/keyboard.h

@@ -49,7 +49,8 @@ extern "C" {
 #define KBD_WS2812_POWER_IO  1
 
 /*!< Battery monitor GPIO */
-#define KBD_BATTERY_MONITOR_IO  2
+#define KBD_BATTERY_MONITOR_IO      2
+#define KBD_BATTERY_MONITOR_CHANNEL ADC_CHANNEL_1
 
 #ifdef __cplusplus
 }

examples/keyboard/main/CMakeLists.txt

@@ -1,5 +1,5 @@
-idf_component_register(SRCS "main.c" "../hid_device/usb_descriptors.c" "tinyusb_hid.c" "ble_hid.c" "esp_hid_gap.c" "btn_progress.c" "settings.c"
-                    INCLUDE_DIRS "../hid_device")
+idf_component_register(SRCS "main.c" "../hid_device/usb_descriptors.c" "tinyusb_hid.c" "ble_hid.c" "esp_hid_gap.c" "btn_progress.c" "settings.c" "battery_adc.c"
+                       INCLUDE_DIRS "../hid_device")
 
 idf_component_get_property(tusb_lib espressif__tinyusb COMPONENT_LIB)
 

examples/keyboard/main/battery_adc.c

@@ -0,0 +1,111 @@
+/*
+ * SPDX-FileCopyrightText: 2024-2025 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <driver/adc.h>
+
+#include "battery_adc.h"
+
+#include "ble_hid.h"
+#include <esp_log.h>
+#include <esp_adc/adc_oneshot.h>
+
+#include "bsp/esp-bsp.h"
+
+int g_battery_percent;
+
+static const char *TAG = "BATTERY-ADC";
+
+static adc_oneshot_unit_handle_t adc1_handle;
+static TaskHandle_t battery_task_handle = NULL;
+
+static void battery_monitor_task(void *pvParameters);
+
+/* Pull up resistor value. Unit: KOhm */
+#define PULL_UP_RESISTOR    (51)
+/* Pull down resistor value. Unit: KOhm */
+#define PULL_DOWN_RESISTOR  (100)
+/* Max voltage value. Unit: mV */
+#define MAX_REF_VOLTAGE     (3469)
+
+esp_err_t battery_adc_init(void)
+{
+    if (battery_task_handle != NULL) {
+        ESP_LOGW(TAG, "Battery ADC already initialized");
+        return ESP_OK;
+    }
+
+    /* ADC1 Init */
+    adc_oneshot_unit_init_cfg_t unit_init_cfg = {
+        .unit_id = ADC_UNIT_1,
+        .clk_src = ADC_RTC_CLK_SRC_DEFAULT,
+        .ulp_mode = ADC_ULP_MODE_DISABLE
+    };
+    ESP_ERROR_CHECK(adc_oneshot_new_unit(&unit_init_cfg, &adc1_handle));
+
+    /* ADC1 Config */
+    adc_oneshot_chan_cfg_t channel_config = {
+        /* Theoretical battery voltage measurement range is about 2.45 to 2.78V.
+         * So set the input attenuation to 12 dB (about 4x) */
+        .atten = ADC_ATTEN_DB_12,
+        .bitwidth = ADC_BITWIDTH_12
+    };
+    ESP_ERROR_CHECK(adc_oneshot_config_channel(adc1_handle, KBD_BATTERY_MONITOR_CHANNEL, &channel_config));
+
+    ESP_LOGI(TAG, "Free memory size: %"PRIu32, esp_get_free_heap_size());
+    if (xTaskCreate(battery_monitor_task, "battery_monitor", 4096, NULL, 2, &battery_task_handle) != pdPASS) {
+        return ESP_ERR_NO_MEM;
+    }
+    ESP_LOGI(TAG, "Free memory size: %"PRIu32, esp_get_free_heap_size());
+
+    return ESP_OK;
+}
+
+static void battery_monitor_task(void *pvParameters)
+{
+    ESP_UNUSED(pvParameters);
+    /* The table of voltage convert percent. */
+    const static int ocv_capacity_table[] = {
+        3680, 3700, 3740, 3770, 3790, 3820, 3870, 3920, 3980, 4060, 4200
+    };
+
+    int adc_raw_value;
+    int adc_voltage;
+    int battery_voltage;
+
+    int battery_level;
+
+    while (1) {
+        adc_oneshot_read(adc1_handle, KBD_BATTERY_MONITOR_CHANNEL, &adc_raw_value);
+
+        /* Get the battery voltage. */
+        adc_voltage = MAX_REF_VOLTAGE * adc_raw_value / 4095;
+        battery_voltage = adc_voltage * (PULL_UP_RESISTOR + PULL_DOWN_RESISTOR) / PULL_DOWN_RESISTOR;
+
+        /* Get the percent. */
+        for (battery_level = 0; battery_level < 11; ++battery_level) {
+            if (battery_voltage <= ocv_capacity_table[battery_level]) {
+                break;
+            }
+        }
+
+        if (battery_level == 0) {
+            /* Low battery. */
+            g_battery_percent = 0;
+        } else if (battery_level >= 11) {
+            /* Over voltage. */
+            g_battery_percent = 100;
+        } else {
+            g_battery_percent = (battery_level - 1) * 10;
+            g_battery_percent += ((battery_voltage - ocv_capacity_table[battery_level]) * 10 / (
+                                      ocv_capacity_table[battery_level] - ocv_capacity_table[battery_level - 1]));
+        }
+
+        ble_hid_battery_report(g_battery_percent);
+
+        /* Sample period. */
+        vTaskDelay(pdMS_TO_TICKS(10000));
+    }
+}

examples/keyboard/main/battery_adc.h

@@ -0,0 +1,26 @@
+/*
+ * SPDX-FileCopyrightText: 2024-2025 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "esp_err.h"
+
+/**
+ * @brief Initialize battery ADC.
+ *
+ * @return
+ *    - ESP_OK: Success
+ *    - ESP_ERR_NO_MEM: Out of memory.
+ */
+esp_err_t battery_adc_init(void);
+
+#ifdef __cpluscpls
+}
+#endif

examples/keyboard/main/ble_hid.c

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2024-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -161,3 +161,13 @@ void ble_hid_keyboard_report(hid_report_t report)
         break;
     }
 }
+
+void ble_hid_battery_report(int battery_level)
+{
+    if (s_ble_hid_param.is_connected == false) {
+        return;
+    }
+
+    ESP_LOGI(TAG, "Report level: %d", battery_level);
+    esp_hidd_dev_battery_set(s_ble_hid_param.hid_dev, (uint8_t)battery_level);
+}

examples/keyboard/main/ble_hid.h

@@ -1,4 +1,5 @@
-/* SPDX-FileCopyrightText: 2022-2024 Espressif Systems (Shanghai) CO LTD
+/*
+ * SPDX-FileCopyrightText: 2024-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -36,6 +37,13 @@ esp_err_t ble_hid_deinit(void);
  */
 void ble_hid_keyboard_report(hid_report_t report);
 
+/**
+ * @brief Send ble hid battery level
+ *
+ * @param battery_level
+ */
+void ble_hid_battery_report(int battery_level);
+
 #ifdef __cplusplus
 }
 #endif

examples/keyboard/main/main.c

@@ -10,6 +10,7 @@
 #include "bsp/esp-bsp.h"
 #include "bsp/keycodes.h"
 #include "btn_progress.h"
+#include "battery_adc.h"
 #include "esp_log.h"
 #include "esp_pm.h"
 #include "keyboard_button.h"
@@ -115,4 +116,5 @@ void app_main(void)
     keyboard_button_register_cb(kbd_handle, cb_cfg, NULL);
 
     xTaskCreate(light_progress_task, "light_progress_task", 4096, NULL, 5, &light_progress_task_handle);
+    battery_adc_init();
 }