Added support for storing settings in FLASH.

src/Config.h

@@ -60,14 +60,18 @@
   const uint8_t SIG_SYNCED = 0x02;
   const uint8_t RX_ONGOING = 0x04;
   
+  // The size of this struc should be a exactly 256 bytes, which is the FLASH_PAGE_SIZE of the RPi pico's flash memory
   struct aprssettings {
-      uint8_t MyCall[10] = { 'P','E','1','R','X','F','-','5', 0} ;
-      uint8_t ServerCall[10] = { 'P','E','1','R','X','F','-','3', 0} ;
-      uint8_t Destination[10] = { 'A','P','Z','M','D','M', 0} ;
-      uint8_t Path1[10] = { 0,'I','D','E','1','-', '1', 0} ;
-      uint8_t Path2[10] = { 0,'I','D','E','2','-', '2', 0} ; 
-      
-      uint8_t FirmwareVersion[20] = { 'V','1',',','C','o','n','t','r', 'o','l','l','e','r',' ','0','1', 0} ;
+      uint8_t ValidFlashData = 0x5A;  // Indicates flash contains valid data - 1 bytes
+      uint8_t MyCall[10] = { 'N','O','C','A','L','L','-','2', 0} ;      // 10 bytes
+      uint8_t ServerCall[10] = { 'N','O','C','A','L','L','-','1', 0} ;  // 10 bytes
+      uint8_t Destination[10] = { 'A','P','Z','M','D','M', 0} ;         // 10 bytes
+      uint8_t Path1[10] = { 0,'I','D','E','1','-', '1', 0} ;            // 10 bytes
+      uint8_t Path2[10] = { 0,'I','D','E','2','-', '2', 0} ;            // 10 bytes
+            
+      uint8_t FirmwareVersion[20] = { 'V','1',',','C','o','n','t','r', 'o','l','l','e','r',' ','0','1', 0} ;    // 20 bytes
+                                                                        // 71 bytes total
+      uint8_t FillerData[256-71];
   } AprsSettings;
   
   struct status {

src/main.cpp

@@ -3,12 +3,13 @@
 #include <time.h>
 #include "pico/stdlib.h"
 #include "pico/binary_info.h"
+#include "hardware/flash.h"
 #include "LoRa-RP2040.h"
 #include "Config.h"
 #include "KISS.h"
+#include "hardware/claim.h"
 
 bool startRadio();
-bool LoadSettings();
 void getPacketData(int packetLength);
 int compare_strings(uint8_t a[], uint8_t b[]);
 bool is_message_for_me (uint8_t data[], uint8_t mycall[]);
@@ -27,14 +28,49 @@ const uint PowerSupply5VControl  = 4;
 const uint RelayOffControl       = 2;
 const uint RelayOnControl        = 3;
 
-int main() {
+// We're going to use a region 256k from the start of flash as non volatile storage for our settings.
+// We can access this at XIP_BASE + 256k.
+#define FLASH_TARGET_OFFSET (512 * 1024)
+
+const uint8_t *flash_target_contents = (const uint8_t *) (XIP_BASE + FLASH_TARGET_OFFSET);
+
+uint8_t ReadSettingsFromFlash(void)
+{
     
-    uint16_t ServerCommand = 0;
-    uint16_t TxDelay = 0;
-  
-   /* Among others, this initializes the USB-serial port at 115200bps 8N1 */
+    // If byte zero of flash contains 0x5A we assume the data to be valid, otherwise we fill the flash with default values.
+    if (flash_target_contents[0] != 0x5A)
+    {
+        printf( "No valid data found in FLASH memory.\n" );
+        memset(AprsSettings.FillerData, 0, sizeof(AprsSettings.FillerData));
+        uint32_t ints = save_and_disable_interrupts();
+        
+        // First we erase the FLASH sector we need. After that we can store new values.
+        // Note that a whole number of sectors must be erased at a time.
+        // Sector size is 4kB, so this is way bigger than the needed 256 bytes for storing the settings.
+        printf("Erasing FLASH region...");
+        flash_range_erase(FLASH_TARGET_OFFSET, FLASH_SECTOR_SIZE);
+        printf("done\n");
+        printf("Writing default values to FLASH...");    
+        flash_range_program(FLASH_TARGET_OFFSET, (uint8_t*)&AprsSettings, FLASH_PAGE_SIZE);
+        printf("done\n");
+        restore_interrupts (ints);
+    } else {
+        // Read settings stored in flash memory
+        printf("Found valid settings in FLASH memory.\n");
+    }
+    memcpy((uint8_t*)&AprsSettings, flash_target_contents, FLASH_PAGE_SIZE);
+        
+    printf("APRS settings:\n");
+    printf("My call: %s\n", AprsSettings.MyCall);
+    printf("Server call: %s\n", AprsSettings.ServerCall);
+    printf("Firmware: %s\n",AprsSettings.FirmwareVersion);
+}
+
+void setup(void)
+{
+    /* Among others, this initializes the USB-serial port at 115200bps 8N1 */
    stdio_init_all();
-    
+
    // Buffers
    memset(rxBuffer, 0, sizeof(rxBuffer));
    memset(txBuffer, 0, sizeof(txBuffer));
@@ -63,12 +99,20 @@ int main() {
    gpio_put(RelayOffControl, 0);
    gpio_put(RelayOnControl, 0);
    Status.ControlRelay = OFF;
-    
+   
    sleep_ms(5000);
    
-   LoadSettings();
-
+   ReadSettingsFromFlash();
+   
    startRadio();
+}
+
+int main() {
+    
+    uint16_t ServerCommand = 0;
+    uint16_t TxDelay = 0;
+  
+   setup();
     
    while (1) {
       int packetSize = LoRa.parsePacket();
@@ -196,16 +240,6 @@ int main() {
   return 0;
 }
 
-/*
- * Load settings from EEPROM
- */
-bool LoadSettings()
-{
-    printf("APRS settings:\n");
-    printf("My call: %s\n", AprsSettings.MyCall);
-    printf("Server call: %s\n", AprsSettings.ServerCall);
-    
-}
 /*
  * Initializes the LoRa module with the parameters set in config.h
  */