Add UART multiplexer and INA226 monitoring

main/ina226_monitor.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+
+#include "esp_err.h"
+
+typedef struct {
+    float voltage_v;
+    float current_ma;
+    float power_mw;
+} ina226_reading_t;
+
+esp_err_t ina226_monitor_init(void);
+bool ina226_monitor_ready(void);
+size_t ina226_monitor_channel_count(void);
+esp_err_t ina226_monitor_sample(ina226_reading_t *out_reading);
+const ina226_reading_t *ina226_monitor_get_last(void);