From 57715ad5c0c53cb4f8fc2de55c040f9c10944be2 Mon Sep 17 00:00:00 2001
From: Felix Rusu <felix@lowpowerlab.com>
Date: Tue, 29 Jul 2014 17:10:06 -0400
Subject: [PATCH] Unintrusive SPI transactions & misc fixes

---
 SPIFlash.cpp | 38 ++++++++++++++++++--------------------
 SPIFlash.h   |  2 ++
 2 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/SPIFlash.cpp b/SPIFlash.cpp
index e1b8bc1..2817242 100644
--- a/SPIFlash.cpp
+++ b/SPIFlash.cpp
@@ -32,38 +32,36 @@ SPIFlash::SPIFlash(uint8_t slaveSelectPin, uint16_t jedecID) {
 
 /// Select the flash chip
 void SPIFlash::select() {
-#ifdef SPI_HAS_TRANSACTION
-  SPI.beginTransaction(SPISettings(33000000, MSBFIRST, SPI_MODE0));
-#else
   noInterrupts();
-#endif
+  //save current SPI settings
+  _SPCR = SPCR;
+  _SPSR = SPSR;
+  //set FLASH chip SPI settings
+  SPI.setDataMode(SPI_MODE0);
+  SPI.setBitOrder(MSBFIRST);
+  SPI.setClockDivider(SPI_CLOCK_DIV4); //decided to slow down from DIV2 after SPI stalling in some instances, especially visible on mega1284p when RFM69 and FLASH chip both present
+  SPI.begin();
   digitalWrite(_slaveSelectPin, LOW);
 }
 
 /// UNselect the flash chip
 void SPIFlash::unselect() {
   digitalWrite(_slaveSelectPin, HIGH);
-#ifdef SPI_HAS_TRANSACTION
-  SPI.endTransaction();
-#else
+  //restore SPI settings to what they were before talking to the FLASH chip
+  SPCR = _SPCR;
+  SPSR = _SPSR;
   interrupts();
-#endif
 }
 
 /// setup SPI, read device ID etc...
 boolean SPIFlash::initialize()
 {
+  _SPCR = SPCR;
+  _SPSR = SPSR;
   pinMode(_slaveSelectPin, OUTPUT);
-#ifdef SPI_HAS_TRANSACTION
-  digitalWrite(_slaveSelectPin, HIGH);
-#else
   unselect();
-  SPI.setDataMode(SPI_MODE0);
-  SPI.setBitOrder(MSBFIRST);
-  SPI.setClockDivider(SPI_CLOCK_DIV2); //max speed, except on Due which can run at system clock speed
-#endif
-  SPI.begin();
-
+  wakeup();
+  
   if (_jedecID == 0 || readDeviceId() == _jedecID) {
     command(SPIFLASH_STATUSWRITE, true); // Write Status Register
     SPI.transfer(0);                     // Global Unprotect
@@ -228,16 +226,16 @@ void SPIFlash::blockErase32K(long addr) {
 }
 
 void SPIFlash::sleep() {
-  command(SPIFLASH_SLEEP); // Block Erase
+  command(SPIFLASH_SLEEP);
   unselect();
 }
 
 void SPIFlash::wakeup() {
-  command(SPIFLASH_WAKE); // Block Erase
+  command(SPIFLASH_WAKE);
   unselect();
 }
 
 /// cleanup
 void SPIFlash::end() {
   SPI.end();
-}
+}
\ No newline at end of file
diff --git a/SPIFlash.h b/SPIFlash.h
index 20863c1..f0c071a 100644
--- a/SPIFlash.h
+++ b/SPIFlash.h
@@ -93,6 +93,8 @@ protected:
   void unselect();
   byte _slaveSelectPin;
   uint16_t _jedecID;
+  byte _SPCR;
+  byte _SPSR;
 };
 
 #endif
\ No newline at end of file