From 3def3ab00095467a05f5f0b05841d528a058327c Mon Sep 17 00:00:00 2001
From: Bill2462 <burza7@vp.pl>
Date: Sun, 10 Sep 2017 13:58:49 +0200
Subject: [PATCH] Add power control functions  (#334)

* Update MFRC522.h
Add new power control functions :
PCD_SoftPowerDown
PCD_SoftPowerUp
---
 keywords.txt    |  6 +++++-
 src/MFRC522.cpp | 29 +++++++++++++++++++++++++++++
 src/MFRC522.h   |  6 ++++++
 3 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/keywords.txt b/keywords.txt
index 46363a7..c3c1405 100644
--- a/keywords.txt
+++ b/keywords.txt
@@ -43,6 +43,10 @@ PCD_GetAntennaGain	KEYWORD2
 PCD_SetAntennaGain	KEYWORD2
 PCD_PerformSelfTest	KEYWORD2
 
+# Power control functions MFRC522
+PCD_SoftPowerDown	KEYWORD2
+PCD_SoftPowerUp	KEYWORD2
+
 # Functions for communicating with PICCs
 PCD_TransceiveData	KEYWORD2
 PCD_CommunicateWithPICC	KEYWORD2
@@ -216,4 +220,4 @@ FIFO_SIZE	LITERAL1
 BITRATE_106KBITS	LITERAL1
 BITRATE_212KBITS	LITERAL1
 BITRATE_424KBITS	LITERAL1
-BITRATE_848KBITS	LITERAL1
\ No newline at end of file
+BITRATE_848KBITS	LITERAL1
diff --git a/src/MFRC522.cpp b/src/MFRC522.cpp
index 95bf498..4287a2b 100644
--- a/src/MFRC522.cpp
+++ b/src/MFRC522.cpp
@@ -363,6 +363,35 @@ bool MFRC522::PCD_PerformSelfTest() {
 	return true;
 } // End PCD_PerformSelfTest()
 
+/////////////////////////////////////////////////////////////////////////////////////
+// Power control
+/////////////////////////////////////////////////////////////////////////////////////
+
+//IMPORTANT NOTE!!!!
+//Calling any other function that uses CommandReg will disable soft power down mode !!!
+//For more details about power control, refer to the datasheet - page 33 (8.6)
+
+void MFRC522::PCD_SoftPowerDown(){//Note : Only soft power down mode is available throught software
+	byte val = PCD_ReadRegister(CommandReg); // Read state of the command register 
+	val |= (1<<4);// set PowerDown bit ( bit 4 ) to 1 
+	PCD_WriteRegister(CommandReg, val);//write new value to the command register
+}
+
+void MFRC522::PCD_SoftPowerUp(){
+	byte val = PCD_ReadRegister(CommandReg); // Read state of the command register 
+	val &= ~(1<<4);// set PowerDown bit ( bit 4 ) to 0 
+	PCD_WriteRegister(CommandReg, val);//write new value to the command register
+	// wait until PowerDown bit is cleared (this indicates end of wake up procedure) 
+	const uint32_t timeout = (uint32_t)millis() + 500;// create timer for timeout (just in case) 
+	
+	while(millis()<=timeout){ // set timeout to 500 ms 
+		val = PCD_ReadRegister(CommandReg);// Read state of the command register
+		if(!(val & (1<<4))){ // if powerdown bit is 0 
+			break;// wake up procedure is finished 
+		}
+	}
+}
+
 /////////////////////////////////////////////////////////////////////////////////////
 // Functions for communicating with PICCs
 /////////////////////////////////////////////////////////////////////////////////////
diff --git a/src/MFRC522.h b/src/MFRC522.h
index a0e5f9f..6a3a54f 100644
--- a/src/MFRC522.h
+++ b/src/MFRC522.h
@@ -359,6 +359,12 @@ public:
 	void PCD_SetAntennaGain(byte mask);
 	bool PCD_PerformSelfTest();
 	
+	/////////////////////////////////////////////////////////////////////////////////////
+	// Power control functions
+	/////////////////////////////////////////////////////////////////////////////////////
+	void PCD_SoftPowerDown();
+	void PCD_SoftPowerUp();
+	
 	/////////////////////////////////////////////////////////////////////////////////////
 	// Functions for communicating with PICCs
 	/////////////////////////////////////////////////////////////////////////////////////