power saving: enable DCDC, reduce clock speeds and voltage

variants/rpi_picow/PicoWBoard.cpp

@@ -19,6 +19,66 @@ static void disconnect_callback(uint16_t conn_handle, uint8_t reason) {
 }
 
 void PicoWBoard::begin() {
+  // 1. Force SMPS to PFM (Power Save) Mode
+  pinMode(PIN_SMPS_MODE, OUTPUT);
+  digitalWrite(PIN_SMPS_MODE, LOW);
+
+  // 2. Detect Power Source
+  pinMode(PIN_VBUS_DET, INPUT);
+  bool usb_connected = digitalRead(PIN_VBUS_DET);
+
+  if (usb_connected) {
+    // --- USB MODE (Performance) ---
+    // Must run at 48MHz+ for USB to work
+    set_sys_clock_khz(48000, true); 
+
+    // Ensure USB Clock is enabled
+    clock_configure(clk_usb,
+                    0,
+                    CLOCKS_CLK_USB_CTRL_AUXSRC_VALUE_CLKSRC_PLL_USB,
+                    48 * MHZ,
+                    48 * MHZ);
+
+    // Ensure ADC runs from USB PLL (Standard 48MHz)
+    clock_configure(clk_adc,
+                    0,
+                    CLOCKS_CLK_ADC_CTRL_AUXSRC_VALUE_CLKSRC_PLL_USB,
+                    48 * MHZ,
+                    48 * MHZ);
+
+  } else {
+    // --- BATTERY MODE (Deep Power Saving) ---
+
+    // A. Move ADC to System Clock BEFORE killing USB PLL
+    // This keeps the ADC alive, even though USB PLL is about to die.
+    // It will run at 18MHz (Slower, but fine for battery reading).
+    clock_configure(clk_adc,
+                    0,
+                    CLOCKS_CLK_ADC_CTRL_AUXSRC_VALUE_CLKSRC_PLL_SYS,
+                    18 * MHZ,
+                    18 * MHZ);
+
+    // B. Drop System Clock to 18 MHz
+    set_sys_clock_khz(18000, true); 
+
+    // C. Disable USB Clock & PLL
+    // The USB PLL consumes ~2-3mA. We turn it off it here.
+    clock_stop(clk_usb);
+    pll_deinit(pll_usb);
+
+    // D. Lower Core Voltage to 0.95V
+    vreg_set_voltage(VREG_VOLTAGE_0_95);
+  }
+
+  // 3. Reconfigure Peripheral Clock to match System Clock
+  // This ensures UART/SPI timings stay correct at the new 18MHz speed
+  clock_configure(clk_peri,
+                  0,
+                  CLOCKS_CLK_ADC_CTRL_AUXSRC_VALUE_CLKSRC_PLL_SYS, // Run peripherals from Sys Clock
+                  usb_connected ? 48000 * 1000 : 18000 * 1000,
+                  usb_connected ? 48000 * 1000 : 18000 * 1000);
+
+
   // for future use, sub-classes SHOULD call this from their begin()
   startup_reason = BD_STARTUP_NORMAL;
   pinMode(PIN_VBAT_READ, INPUT);

variants/rpi_picow/PicoWBoard.h

@@ -3,6 +3,18 @@
 #include <MeshCore.h>
 #include <Arduino.h>
 
+// RP2040 Specific Includes for Clock/Power
+#include "pico/stdlib.h"
+#include "hardware/vreg.h"
+#include "hardware/clocks.h"
+#include "hardware/pll.h"
+#include "hardware/structs/pll.h"
+#include "hardware/structs/clocks.h"
+
+// Pico Standard Pins
+#define PIN_SMPS_MODE 23
+#define PIN_VBUS_DET  24
+
 // built-ins
 #define  PIN_VBAT_READ    26
 #define  ADC_MULTIPLIER   (3.1 * 3.3 * 1000) // MT Uses 3.1