Libraries: modernize Portenta_SDRAM and add example

Author: facchinm

Diff for: libraries/Portenta_SDRAM/examples/SDRAM_operations/SDRAM_operations.ino

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+/*
+    How to interact with external SDRAM on Portenta H7
+
+    The board comes with an hefty 8MB of external fast RAM, which can be used:
+    - as a framebuffer (raw mode)
+    - as an expansion of on-chip RAM to store "standard" data
+
+    This example shows both the usages
+*/
+
+#include "SDRAM.h"
+
+REDIRECT_STDOUT_TO(Serial);
+
+void nonFrameBuffer() {
+    // Initilize SDRAM for non-framebuffer operations
+    SDRAM.begin(); // is the same as SDRAM.begin(SDRAM_START_ADDRESS);
+
+    // Now we can malloc() and free() in the whole RAM space
+    // For example, let's create a 7MB array
+    uint8_t* myVeryBigArray = (uint8_t*)SDRAM.malloc(7 * 1024 * 1024);
+
+    // and a small one
+    uint8_t* mySmallArray = (uint8_t*)SDRAM.malloc(128);
+
+    // and use then as usual
+    for (int i = 0; i<128; i++) {
+        myVeryBigArray[i] = i;
+        mySmallArray[i] = i*2;
+    }
+
+    // free the memory when you don't need them anymore
+    SDRAM.free(myVeryBigArray);
+}
+
+void frameBuffer() {
+    // In case we want a framebuffer-like area at the beginning of the flash,
+    // simply initialize the memory as
+
+    SDRAM.begin(SDRAM_START_ADDRESS + 2 * 1024 * 1024);
+    // 2MB of contiguous memory available at the beginning
+
+    uint32_t* framebuffer = (uint32_t*)SDRAM_START_ADDRESS;
+
+    // We can't allocate anymore the huge 7MB array
+
+    uint8_t* myVeryBigArray = (uint8_t*)SDRAM.malloc(7 * 1024 * 1024);
+    if (myVeryBigArray == NULL) {
+        Serial.println("Oops, too big :)");
+    }
+
+}
+
+void setup() {
+    Serial.begin(115200);
+    while (!Serial);
+
+    frameBuffer();
+    // Uncomment to test the other functionality 
+    // noFrameBuffer();
+
+    // Sort of memtest fo stability, useful for testing when overclocking
+    if (SDRAM.test()) {
+        Serial.println("SDRAM completely functional");
+    }
+}
+
+void loop() {
+    
+}

Diff for: libraries/Portenta_SDRAM/library.properties

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+name=Portenta_SDRAM
+version=1.0
+author=Arduino
+maintainer=Arduino <[email protected]>
+sentence=Interact with external SDRAM chip on Portenta H7
+paragraph=
+category=Other
+url=https://github.com/arduino/ArduinoCore-mbed/tree/master/libraries/RPC
+architectures=mbed,mbed_portenta