Fix PI recall in memory mode

Also added PI check on manual entries and updated the doc

TEF6686_ESP32.ino

@@ -2764,9 +2764,11 @@ void DoMemoryPosTune() {
   }
 
   if (presets[memorypos].RDSPI[0] != '\0') {
-    for (byte i = 0; i < 5; i++) {
+    for (byte i = 0; i < 4; i++) {
       radio.rds.picode[i] = presets[memorypos].RDSPI[i];
     }
+    radio.rds.picode[4] = ' ';
+    radio.rds.picode[5] = ' ';
     radio.rds.picode[6] = '\0';
     radio.rds.correctPI = (uint16_t)strtol(radio.rds.picode, NULL, 16);
   } else {

src/comms.cpp

@@ -258,6 +258,16 @@ void Communication() {
 
                   if (memms > 1) error |= (1 << 3);
 
+                  if (rdsPi[0] != '\0') {
+                    for (int i = 0; i < 4; i++) {
+                      char c = rdsPi[i];
+                      if (!((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F'))) {
+                        error |= (1 << 5);
+                        break;
+                      }
+                    }
+                  }
+
                   if (error == 0) {
                     error |= (1 << 7);
                     memorypos = mempos;