Arduino: modular structure

arduino/main/voltage.cpp

@@ -0,0 +1,27 @@
+#include "voltage.h"
+
+// Pin definitions
+static const int PIN_VBAT = A0;
+
+// Voltage divider constants
+// Divider: 100k upper (to Vin), 47k lower (to GND)
+// Vout = Vin * (47k / (100k + 47k)) = Vin * 0.3197
+// At 12V: ADC sees 3.84V | At 14.4V: ADC sees 4.60V
+static const float DIVIDER_RATIO = 47.0 / (100.0 + 47.0);  // ~0.3197
+static const float ADC_REF = 5.0;
+static const int ADC_MAX = 1023;
+
+void voltage_init() {
+  // analogRead doesn't need explicit pinMode, but here for future config
+  // e.g., could switch to internal 1.1V reference for different range
+}
+
+int voltage_read_raw() {
+  return analogRead(PIN_VBAT);
+}
+
+float voltage_read() {
+  int raw = voltage_read_raw();
+  float vDivider = (raw / (float)ADC_MAX) * ADC_REF;
+  return vDivider / DIVIDER_RATIO;
+}