From 3b1934e6683cea86be1435db86efb836105a0e40 Mon Sep 17 00:00:00 2001
From: FUEL4EP <epre@unitybox.de>
Date: Tue, 26 Mar 2024 10:29:25 +0100
Subject: [PATCH] added Fujitsu MB85RS4MT FRAM; added sleep mode

---
 Adafruit_FRAM_SPI.cpp | 37 +++++++++++++++++++++++++++++++++++++
 Adafruit_FRAM_SPI.h   | 18 +++++++++++-------
 2 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/Adafruit_FRAM_SPI.cpp b/Adafruit_FRAM_SPI.cpp
index 9284998..4622fc2 100644
--- a/Adafruit_FRAM_SPI.cpp
+++ b/Adafruit_FRAM_SPI.cpp
@@ -46,6 +46,7 @@ const struct {
     {0x04, 0x2503, 32 * 1024UL},  // MB85RS256TY
     {0x04, 0x2703, 128 * 1024UL}, // MB85RS1MT
     {0x04, 0x4803, 256 * 1024UL}, // MB85RS2MTA
+    {0x04, 0x2803, 256 * 1024UL}, // MB85RS2MT
     {0x04, 0x4903, 512 * 1024UL}, // MB85RS4MT
 
     // Cypress
@@ -343,3 +344,39 @@ bool Adafruit_FRAM_SPI::setStatusRegister(uint8_t value) {
 void Adafruit_FRAM_SPI::setAddressSize(uint8_t nAddressSize) {
   _nAddressSizeBytes = nAddressSize;
 }
+
+/*!
+ *  @brief  Enters the FRAM's low power sleep mode
+ *  @return true if successful
+ */
+// WARNING: this method has not yet been validated
+bool Adafruit_FRAM_SPI::enter_low_power_mode(void) {
+  uint8_t cmd;
+
+  cmd = OPCODE_SLEEP;
+
+  return spi_dev->write(&cmd, 1);
+}
+
+
+/*!
+ *  @brief  exits the FRAM's low power sleep mode
+ *  @return true if successful
+ */
+// WARNING: this method has not yet been validated
+bool Adafruit_FRAM_SPI::exit_low_power_mode(void) {
+  uint8_t cmd;
+
+  // Returning to an normal operation from the SLEEP mode is carried out after tREC (Max 400 μs)
+  // time from the falling edge of CS
+  spi_dev->beginTransactionWithAssertingCS();
+  delayMicroseconds(300);
+  // It is possible to return CS to H level before tREC time. However, it
+  // is prohibited to bring down CS to L level again during tREC period.
+  spi_dev->endTransactionWithDeassertingCS();
+  delayMicroseconds(100);
+
+  return spi_dev->write(&cmd, 1);
+}
+
+
diff --git a/Adafruit_FRAM_SPI.h b/Adafruit_FRAM_SPI.h
index 3baf249..214adae 100644
--- a/Adafruit_FRAM_SPI.h
+++ b/Adafruit_FRAM_SPI.h
@@ -18,6 +18,7 @@
  *
  *  BSD license, all text above must be included in any redistribution
  */
+
 #ifndef _ADAFRUIT_FRAM_SPI_H_
 #define _ADAFRUIT_FRAM_SPI_H_
 
@@ -27,13 +28,14 @@
 
 /** Operation Codes **/
 typedef enum opcodes_e {
-  OPCODE_WREN = 0b0110,    /* Write Enable Latch */
-  OPCODE_WRDI = 0b0100,    /* Reset Write Enable Latch */
-  OPCODE_RDSR = 0b0101,    /* Read Status Register */
-  OPCODE_WRSR = 0b0001,    /* Write Status Register */
-  OPCODE_READ = 0b0011,    /* Read Memory */
-  OPCODE_WRITE = 0b0010,   /* Write Memory */
-  OPCODE_RDID = 0b10011111 /* Read Device ID */
+  OPCODE_WREN  = 0b0110,     /* Write Enable Latch */
+  OPCODE_WRDI  = 0b0100,     /* Reset Write Enable Latch */
+  OPCODE_RDSR  = 0b0101,     /* Read Status Register */
+  OPCODE_WRSR  = 0b0001,     /* Write Status Register */
+  OPCODE_READ  = 0b0011,     /* Read Memory */
+  OPCODE_WRITE = 0b0010,     /* Write Memory */
+  OPCODE_RDID  = 0b10011111, /* Read Device ID */
+  OPCODE_SLEEP = 0b10111001  /* Sleep Mode  */ // added by FUEL4EP
 } opcodes_t;
 
 /*!
@@ -56,6 +58,8 @@ class Adafruit_FRAM_SPI {
   uint8_t getStatusRegister(void);
   bool setStatusRegister(uint8_t value);
   void setAddressSize(uint8_t nAddressSize);
+  bool enter_low_power_mode(void); // added by FUEL4EP
+  bool exit_low_power_mode(void);  // added by FUEL4EP
 
 private:
   Adafruit_SPIDevice *spi_dev = NULL;