Merge pull request #20 from arduino-libraries/AE-591_3v3_rail_turns_back_on_when_entering_standby_mode

AE-591: "turnOffEthernet" relocation to be executed before turning rails off.

Author: sebromero

src/Board.cpp

@@ -2,6 +2,11 @@
 #include "MAX1726Driver.h"
 #include <map>
 
+#if defined(ARDUINO_PORTENTA_H7)
+#include "Arduino_LowPowerPortentaH7.h"
+LowPowerPortentaH7& lowPowerPortentaH7 = LowPowerPortentaH7::getInstance();
+#endif
+
 constexpr int UNKNOWN_VALUE = 0xFF;
 
 std::map<float, Ldo2Voltage> ldo2VoltageMap = {
@@ -194,8 +199,28 @@ void Board::setAllPeripheralsPower(bool on){
         PMIC.getControl() -> turnLDO3On(Ldo3Mode::Normal);
         PMIC.getControl() -> turnSw1On(Sw1Mode::Normal);
     } else {
-        PMIC.getControl() -> turnLDO2Off(Ldo2Mode::Normal);
+        #if defined(ARDUINO_PORTENTA_H7)
+        // Ethernet must be turned off before we enter Standby Mode, because
+        // otherwise, the Ethernet transmit termination resistors will overheat
+        // from the voltage that gets applied over them. It would be 125 mW in each
+        // of them, while they are rated at 50 mW. If we fail to turn off Ethernet,
+        // we must not proceed.
+
+        if (false == lowPowerPortentaH7.turnOffEthernet())
+        {
+            {
+                while(1)
+                {
+                    digitalWrite(LEDR, LOW);
+                    delay(500);
+                    digitalWrite(LEDR, HIGH);
+                    delay(500);
+                }
+            }
+        }
+        #endif
         PMIC.getControl() -> turnLDO1Off(Ldo1Mode::Normal);
+        PMIC.getControl() -> turnLDO2Off(Ldo2Mode::Normal);
         PMIC.getControl() -> turnLDO3Off(Ldo3Mode::Normal);
         PMIC.getControl() -> turnSw1Off(Sw1Mode::Normal);
     }