added example + better description in src

Author: unsurv

Diff for: examples/Example22_PowerOff/Example22_PowerOff.ino

@@ -0,0 +1,85 @@
+/*
+  Powering off a ublox GPS module
+  By: bjorn
+  unsurv.org
+  Date: July 20th, 2020
+  License: MIT. See license file for more information but you can
+  basically do whatever you want with this code.
+
+  This example shows you how to turn off the ublox module to lower the power consumption.
+  There are two functions: one just specifies a duration in milliseconds the other also specifies a pin on the GPS device to wake it up with.
+  By driving a voltage from LOW to HIGH or HIGH to LOW on the chosen module pin you wake the device back up.
+  Note: Doing so on the INT0 pin when using the regular powerOff(durationInMs) function will wake the device anyway. (tested on SAM-M8Q)
+  Note: While powered off, you should not query the device for data or it might wake up. This can be used to wake the device but is not recommended.
+        Works best when also putting your microcontroller to sleep.
+
+  Feel like supporting open source hardware?
+  Buy a board from SparkFun!
+  ZED-F9P RTK2: https://www.sparkfun.com/products/15136
+  NEO-M8P RTK: https://www.sparkfun.com/products/15005
+  SAM-M8Q: https://www.sparkfun.com/products/15106
+
+  Hardware Connections:
+  Plug a Qwiic cable into the GPS and a BlackBoard.
+  To force the device to wake up you need to connect to a pin (for example INT0) seperately on the module.
+  If you don't have a platform with a Qwiic connection use the SparkFun Qwiic Breadboard Jumper (https://www.sparkfun.com/products/14425)
+  Open the serial monitor at 115200 baud to see the output
+*/
+
+#include "SparkFun_Ublox_Arduino_Library.h" //http://librarymanager/All#SparkFun_Ublox_GPS
+SFE_UBLOX_GPS myGPS;
+
+// define a digital pin capable of driving HIGH and LOW
+#define WAKEUP_PIN 5
+
+// interrupt pin mapping
+#define GPS_RX     0
+#define GPS_INT0   1
+#define GPS_INT1   2
+#define GPS_SPI_CS 3
+
+
+void wakeUp() {
+
+  Serial.print("-- waking up module via pin " + String(WAKEUP_PIN));
+  Serial.println(" on your microcontroller --");
+
+  digitalWrite(WAKEUP_PIN, LOW);
+  delay(1000);
+  digitalWrite(WAKEUP_PIN, HIGH);
+  delay(1000);
+  digitalWrite(WAKEUP_PIN, LOW);
+}
+
+
+void setup() {
+
+  pinMode(WAKEUP_PIN, OUTPUT);
+
+  Serial.begin(115200);
+  while (!Serial); //Wait for user to open terminal
+  Serial.println("SparkFun Ublox Example");
+
+  Wire.begin();
+
+  if (myGPS.begin() == false) //Connect to the Ublox module using Wire port
+  {
+    Serial.println(F("Ublox GPS not detected at default I2C address. Please check wiring. Freezing."));
+    while (1);
+  }
+
+  // Powering off for 20s, you should see the power consumption drop.
+  Serial.println("-- Powering off module for 20s --");
+
+  myGPS.powerOff(20000);
+  // myGPS.powerOffWithInterrupt(20000, GPS_INT0);
+
+  delay(10000);
+
+  // After 10 seconds wake the device via the specified pin on your microcontroller and module.
+  wakeUp();
+}
+
+void loop() {
+  //Do nothing
+}

Diff for: src/SparkFun_Ublox_Arduino_Library.cpp

@@ -2571,8 +2571,8 @@ uint8_t SFE_UBLOX_GPS::getPowerSaveMode(uint16_t maxWait)
 
 // Powers off the GPS device for a given duration to reduce power consumption.
 // NOTE: Querying the device before the duration is complete, for example by "getLatitude()" will wake it up!
-// returns true if command has not failed
-// returns false if command has not been acknowledged or maxWait = 0
+// Returns true if command has not been not acknowledged.
+// Returns false if command has not been acknowledged or maxWait = 0.
 boolean SFE_UBLOX_GPS::powerOff(uint32_t durationInMs,  uint16_t maxWait)
 {
   // use durationInMs = 0 for infinite duration
@@ -2610,10 +2610,10 @@ boolean SFE_UBLOX_GPS::powerOff(uint32_t durationInMs,  uint16_t maxWait)
 
 // Powers off the GPS device for a given duration to reduce power consumption.
 // While powered off it can be woken up by creating a falling or rising voltage edge on the specified pin.
-// NOTE: The GPS seems to detect small voltage edges on the interrupt pin. Works best when Microcontroller is in deepsleep.
+// NOTE: The GPS seems to be sensitve to signals on the pins while powered off. Works best when Microcontroller is in deepsleep.
 // NOTE: Querying the device before the duration is complete, for example by "getLatitude()" will wake it up!
-// returns true if command has not failed
-// returns false if command has not been acknowledged or maxWait = 0
+// Returns true if command has not been not acknowledged.
+// Returns false if command has not been acknowledged or maxWait = 0.
 boolean SFE_UBLOX_GPS::powerOffWithInterrupt(uint32_t durationInMs, uint8_t wakeupPin, boolean forceWhileUsb, uint16_t maxWait)
 {
   // use durationInMs = 0 for infinite duration