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Updated preferences and FAQ documentation (added SPIFFS) (#8150)

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* Updated preferences.rst

* Added into FAQ info about SPIFFS failed mount
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Tomáš Pilný 2023-05-11 12:49:30 +02:00 committed by GitHub
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2 changed files with 48 additions and 18 deletions
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17
docs/source/faq.rst
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@ -15,3 +15,20 @@ How to compile libs with different debug level?
-----------------------------------------------
The short answer is ``esp32-arduino-lib-builder/configs/defconfig.common:44``. A guide explaining the process can be found here <guides/core_debug>
SPIFFS mount failed
-------------------
When you come across and error like this:
.. code-block:: shell
E (588) SPIFFS: mount failed, -10025
[E][SPIFFS.cpp:47] begin(): Mounting SPIFFS failed! Error: -1
Try enforcing format on fail in your code by adding ``true`` in the ``begin`` method such as this:
.. code-block:: c++
SPIFFS.begin(true);
See the method prototype for reference: ``bool begin(bool formatOnFail=false, const char * basePath="/spiffs", uint8_t maxOpenFiles=10, const char * partitionLabel=NULL);``

49
docs/source/tutorials/preferences.rst
View file

@ -233,9 +233,9 @@ Like so:
.. code-block:: arduino
String myString = myPreferences.getString("myStringKey");
float myFloat = myPreferences.getFloat("pi");
This will retrieve the String value from the namespace key ``"myStringKey"`` and assign it to the String type variable ``myString``.
This will retrieve the float value from the namespace key ``"pi"`` and assign it to the float type variable ``myFloat``.
Summary
@ -277,9 +277,10 @@ When started, the system has no way of knowing which of the above conditions is
// not the complete setup(), but in setup(), include this...
stcPrefs.begin("STCPrefs", RO_MODE); // Open our namespace (or create it
// if it doesn't exist) in in RO mode.
// if it doesn't exist) in RO mode.
bool tpInit = stcPrefs.isKey("nvsInit"); // Test for the existence of the "already initialized" key.
bool tpInit = stcPrefs.isKey("nvsInit"); // Test for the existence
// of the "already initialized" key.
if (tpInit == false) {
// If tpInit is 'false', the key "nvsInit" does not yet exist therefore this
@ -289,13 +290,15 @@ When started, the system has no way of knowing which of the above conditions is
// The .begin() method created the "STCPrefs" namespace and since this is our
// first-time run we will create our keys and store the initial "factory default" values.
// first-time run we will create
// our keys and store the initial "factory default" values.
stcPrefs.putUChar("curBright", 10);
stcPrefs.putString("talChan", "one");
stcPrefs.putLong("talMax", -220226);
stcPrefs.putBool("ctMde", true);
stcPrefs.putBool("nvsInit", true); // Create the "already initialized" key and store a value.
stcPrefs.putBool("nvsInit", true); // Create the "already initialized"
// key and store a value.
// The "factory defaults" are created and stored so...
stcPrefs.end(); // Close the namespace in RW mode and...
@ -456,10 +459,12 @@ This is best explained with an example. Here the ``Bytes`` methods are used to s
Serial.begin(115200);
delay(250);
mySketchPrefs.begin("myPrefs", RW_MODE); // open (or create) the namespace "myPrefs" in RW mode
mySketchPrefs.begin("myPrefs", RW_MODE); // open (or create) the namespace
// "myPrefs" in RW mode
mySketchPrefs.clear(); // delete any previous keys in this namespace
// Create an array of test values. We're using hex numbers throughout to better show how the bytes move around.
// Create an array of test values. We're using hex numbers
// throughout to better show how the bytes move around.
int16_t myArray[] = { 0x1112, 0x2122, 0x3132, 0x4142, 0x5152, 0x6162, 0x7172 };
Serial.println("Printing myArray...");
@ -468,22 +473,28 @@ This is best explained with an example. Here the ``Bytes`` methods are used to s
}
Serial.println("\r\n");
// In the next statement, the second sizeof() needs to match the data type of the elements of myArray
Serial.print("The number of elements in myArray is: "); Serial.println( sizeof(myArray) / sizeof(int16_t) );
Serial.print("But the size of myArray in bytes is: "); Serial.println( sizeof(myArray) );
// In the next statement, the second sizeof() needs
// to match the data type of the elements of myArray
Serial.print("The number of elements in myArray is: ");
Serial.println( sizeof(myArray) / sizeof(int16_t) );
Serial.print("But the size of myArray in bytes is: ");
Serial.println( sizeof(myArray) );
Serial.println("");
Serial.println("Storing myArray into the Preferences namespace \"myPrefs\" against the key \"myPrefsBytes\".");
Serial.println(
"Storing myArray into the Preferences namespace \"myPrefs\" against the key \"myPrefsBytes\".");
// Note: in the next statement, to store the entire array, we must use the
// size of the arrray in bytes, not the number of elements in the array.
mySketchPrefs.putBytes( "myPrefsBytes", myArray, sizeof(myArray) );
Serial.print("The size of \"myPrefsBytes\" is (in bytes): "); Serial.println( mySketchPrefs.getBytesLength("myPrefsBytes") );
Serial.print("The size of \"myPrefsBytes\" is (in bytes): ");
Serial.println( mySketchPrefs.getBytesLength("myPrefsBytes") );
Serial.println("");
int16_t myIntBuffer[20] = {}; // No magic about 20. Just making a buffer (array) big enough.
int16_t myIntBuffer[20] = {}; // No magic about 20. Just making a buffer (array) big enough.
Serial.println("Retrieving the value of myPrefsBytes into myIntBuffer.");
Serial.println(" - Note the data type of myIntBuffer matches that of myArray");
mySketchPrefs.getBytes( "myPrefsBytes", myIntBuffer, mySketchPrefs.getBytesLength("myPrefsBytes") );
mySketchPrefs.getBytes("myPrefsBytes", myIntBuffer,
mySketchPrefs.getBytesLength("myPrefsBytes"));
Serial.println("Printing myIntBuffer...");
// In the next statement, sizeof() needs to match the data type of the elements of myArray
@ -492,9 +503,11 @@ This is best explained with an example. Here the ``Bytes`` methods are used to s
}
Serial.println("\r\n");
Serial.println("We can see how the data from myArray is actually stored in the namespace as follows.");
uint8_t myByteBuffer[40] = {}; // No magic about 40. Just making a buffer (array) big enough.
mySketchPrefs.getBytes( "myPrefsBytes", myByteBuffer, mySketchPrefs.getBytesLength("myPrefsBytes") );
Serial.println(
"We can see how the data from myArray is actually stored in the namespace as follows.");
uint8_t myByteBuffer[40] = {}; // No magic about 40. Just making a buffer (array) big enough.
mySketchPrefs.getBytes("myPrefsBytes", myByteBuffer,
mySketchPrefs.getBytesLength("myPrefsBytes"));
Serial.println("Printing myByteBuffer...");
for (int i = 0; i < mySketchPrefs.getBytesLength("myPrefsBytes"); i++) {