Diff: SPIEEPROM.cpp

Revision:

2:bb0f631a6068

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SPIEEPROM.cpp	Thu Jun 06 20:11:28 2013 +0000
@@ -0,0 +1,122 @@
+/*
+ * SOURCE FILE : SPIEEPROM.cpp
+ *
+ * Definition of class SPIEEPROM.
+ * Rountines for communicating with a serial EEPROM over an SPI link.
+ * EEPROM in question is a Microchip 24AA512.
+ * Remember you need pullup resistors on the SCL, SDA and WP lines.
+ *
+ */
+
+#include "SPIEEPROM.h"
+
+// Instruction set codes for use with EEPROM.
+#define READ 0x03       // read data beginning at selected address
+#define WRITE 0x02      // write data beginning at selected address
+#define WRDI 0x04       // disable write operations
+#define WREN 0x06       // enable write operations
+#define RDSR 0x05       // read status register
+#define WRSR 0x01       // write status register
+
+/***************/
+/* CONSTRUCTOR */
+/***************/
+// Pass pointer to an SPI object in spiLink.
+// Pass pointer to output used as chip select in chipSelect.
+SPIEEPROM::SPIEEPROM( SPI *spiLink, DigitalOut *chipSelect ) :
+    spi( spiLink ),
+    cs( chipSelect )
+{
+}
+
+/**************/
+/* DESTRUCTOR */
+/**************/
+SPIEEPROM::~SPIEEPROM() {
+}
+
+/*************************************/
+/* ATTEMPT TO READ A NUMBER OF BYTES */
+/*************************************/
+// Pass address within EEPROM in address.
+// Pass pointer to buffer for bytes read in buffer.
+// Returns false if a failure occurred whilst reading EEPROM.
+// Pass number of bytes to read in count.
+// Returns true if successful, false if not.
+bool SPIEEPROM::ReadBytes( UInt16 address, UInt8 *buffer, UInt16 count ) {
+    *cs = 0;                                // Select the EEPROM.
+    spi->write( READ );                     // Send read instruction.
+    spi->write( ( address >> 8 ) & 0xFF );  // Send MSB of address.
+    spi->write( address & 0xFF );           // Send LSB of address.
+    // Read back the correct number of bytes by writing zero bytes.
+    // and storing what comes back in the buffer.
+    while( count > 0 ) {
+        *buffer++ = (UInt8)( spi->write( 0 ) );
+        count--;
+    }
+    *cs = 1;                                // Deselect the EEPROM.
+    return true;                            // Always succeeds.
+}
+
+/**************************************/
+/* ATTEMPT TO WRITE A CHUNK TO EEPROM */
+/**************************************/
+// Pass address within EEPROM in address.
+// Pass pointer to buffer of bytes to write in buffer.
+// Pass number of bytes to write in count.
+// Returns true if successful, false if not.
+// The number of bytes written must not exceed CHUNK_SIZE.
+bool SPIEEPROM::WriteChunk( UInt16 address, const UInt8 *buffer, UInt8 count ) {
+#if 0
+  // First send address you want to write to.
+  wire->beginTransmission( slaveAddress );
+  // Add high byte of EEPROM address to write to.
+  wire->send( ( address >> 8 ) & 0xFF );
+  // Add low byte of EEPROM address to write to.
+  wire->send( address & 0xFF );
+    // Add buffer bytes.
+    wire->send( (uint8*)buffer, count );
+  // Send the packet.
+    // Return true if successful.
+  return ( wire->endTransmission() == SUCCESS );
+#else
+  return false;
+#endif
+}
+
+/**************************************/
+/* ATTEMPT TO WRITE A NUMBER OF BYTES */
+/**************************************/
+// Pass address within EEPROM in address.
+// Pass pointer to buffer of bytes to write in buffer.
+// Pass number of bytes to write in count.
+// Returns true if successful, false if not.
+bool SPIEEPROM::WriteBytes( UInt16 address, const UInt8 *buffer, UInt16 count ) {
+#if 0
+    bool ok = true;
+    // Write enable EEPROM and wait a bit.
+    digitalWrite( wp, LOW );
+    delay( 1 );
+    // Keep writing chunks until all bytes written.
+    while( ( count > 0 ) && ok ) {
+        if( count > CHUNK_SIZE ) {
+            ok = WriteChunk( address, buffer, (UInt8)CHUNK_SIZE );
+            address += CHUNK_SIZE;
+            buffer += CHUNK_SIZE;
+            count -= CHUNK_SIZE;
+        }
+        else {
+            ok = WriteChunk( address, buffer, (UInt8)count );
+            count = 0;
+        }
+        // Wait a lot to allow page to be written.
+        delay( 6 );
+    }
+    // Write protect EEPROM.
+    digitalWrite( wp, HIGH );
+    // Return true on success.
+    return ok;
+#else
+  return false;
+#endif
+}