add optional delay after PCD_Init as workaround

provided by DarkiStar #476

README.rst

@@ -242,10 +242,11 @@ Troubleshooting
   #. According to reports #101, #126 and #131, there may be a problem with the soldering on the MFRC522 breakout. You could fix this on your own.
 
 
-* **Firmware Version: 0x12 = (unknown)**
+* **Firmware Version: 0x12 = (unknown) or other random values**
 
-  #. The reason of this behaviour is unknown.
-  #. If this sometimes appear a bad connection or power source is the reason.
+  #. The exact reason of this behaviour is unknown.
+  #. Some boards need more time after `PCD_Init()` to be ready. As workaround add a `delay(4)` directly after `PCD_Init()` to give the PCD more time.
+  #. If this sometimes appears, a bad connection or power source is the reason.
   #. If the firmware version is reported permanent, it is very likely that the hardware is a fake or has a defect. Contact your supplier.
 
 

changes.txt

@@ -1,6 +1,9 @@
 -- Add changes to unreleased tag until we make a release.
 
-31 Mar 2018, v1.4.4
+xx 2019, v1.4.5
+- Updated README
+
+31 Mar 2019, v1.4.4
 - Fixed example
 - Fixed UnbrickUidSector
 - Updated comments

examples/DumpInfo/DumpInfo.ino

@@ -46,6 +46,7 @@ void setup() {
 	while (!Serial);		// Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)
 	SPI.begin();			// Init SPI bus
 	mfrc522.PCD_Init();		// Init MFRC522
+	delay(4);				// Optional delay. Some board do need more time after init to be ready, see Readme
 	mfrc522.PCD_DumpVersionToSerial();	// Show details of PCD - MFRC522 Card Reader details
 	Serial.println(F("Scan PICC to see UID, SAK, type, and data blocks..."));
 }