adding save and battery voltage reading

main/battery.h

@@ -0,0 +1,56 @@
+#ifndef BATTERY_H
+#define BATTERY_H
+
+#include <stdint.h>
+#include "esp_err.h"
+
+// Battery monitoring configuration
+#define BATTERY_ADC_CHANNEL     ADC_CHANNEL_6   // GPIO34 (ADC1_CH6)
+#define BATTERY_ADC_ATTEN       ADC_ATTEN_DB_12 // Full range ~3.9V (0-3300mV with attenuation)
+#define BATTERY_ADC_WIDTH       ADC_WIDTH_BIT_12 // 12-bit resolution (0-4095)
+
+// Battery voltage calculation constants
+// Adjust these based on your voltage divider circuit
+#define BATTERY_VOLTAGE_DIVIDER_RATIO   2.0f    // Example: R1=R2, adjust for your circuit
+#define BATTERY_SAMPLES                 16      // Number of samples to average
+
+// Battery percentage thresholds (in millivolts at battery)
+#define BATTERY_VOLTAGE_MAX     4200    // Fully charged Li-Ion
+#define BATTERY_VOLTAGE_MIN     3000    // Empty Li-Ion (cutoff)
+
+/**
+ * @brief Initialize battery monitoring ADC
+ *
+ * @return esp_err_t ESP_OK on success
+ */
+esp_err_t battery_init(void);
+
+/**
+ * @brief Read raw ADC value from battery pin
+ *
+ * @return int Raw ADC value (0-4095)
+ */
+int battery_read_raw(void);
+
+/**
+ * @brief Read battery voltage in millivolts (averaged)
+ *
+ * @return int Battery voltage in mV
+ */
+int battery_read_voltage_mv(void);
+
+/**
+ * @brief Get battery percentage (0-100)
+ *
+ * @return int Battery percentage
+ */
+int battery_get_percentage(void);
+
+/**
+ * @brief Start battery monitoring task
+ *
+ * This task periodically reads battery voltage and updates system state
+ */
+void battery_start_monitoring_task(void);
+
+#endif // BATTERY_H