Diff: AT45.cpp

Revision:

0:de3e4a57ebe0

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/AT45.cpp	Tue Dec 08 11:58:59 2015 +0000
@@ -0,0 +1,1014 @@
+/* mbed AT45 Library, for driving the Atmel AT45 series Dataflash with Serial Interface (SPI)
+ * Copyright (c) 2012, Created by Steen Joergensen (stjo2809) inspired by Chris Styles AT45 library
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "mbed.h"
+#include "AT45.h"
+#include "nrf_delay.h"
+
+//=============================================================================
+// Public functions
+//=============================================================================
+
+AT45::AT45(SPI& spi, PinName ncs) : _spi(spi), _ncs(ncs)
+{    
+    
+    _pages = -1;        // number of pages
+    _pagesize = -1;     // size of pages 256/264, 512/528, 1024/1056
+    _devicesize = -1;   // In bytes
+    _deep_down = true; // variable for deep power down function (awake ?)
+    _deep_down_onoff = false; // variable for deep power down function (On/Off) 
+
+    _initialize();     // Populate all this stuff
+    
+}
+
+// This function returns the char
+char AT45::read_byte(int address) 
+{   
+    // return byte from address
+    return (_memread( address ));
+}  
+
+int AT45::read_page(char* data, int page)         
+{
+    int address = -1;
+    
+    if(_pagesize == 256)
+    {
+        address = page * 256;
+    }
+    else if(_pagesize == 264)
+    {
+        address = page * 512;
+    }
+    else if(_pagesize == 512)
+    {
+        address = page * 512;
+    }
+    else if(_pagesize == 528)
+    {
+        address = page * 1024;
+    }
+    else if(_pagesize == 1024)
+    {
+        address = page * 1024;
+    }
+    else if(_pagesize == 1056)
+    {
+        address = page * 2048;
+    }
+    else 
+    {
+        return (-1); // something isnt configured right
+    }
+                
+    _busy();        
+    _flashread(1,address); // read the first page of the block into SRAM buffer 1
+    _busy();               // Wait until First page has loaded into buffer 1
+        
+    // this is done directly as we are reading back an entire buffer, and this can be done more optimally than using _sramread
+    _select();
+    _spi.write(0xd4);
+    _sendaddr (0x0);
+    _spi.write (0x0);   // dont care byte
+        
+    for(int i=0; i<_pagesize ;i++) 
+    {
+        data[i] = _spi.write (0x0);  
+    }
+    _deselect();            
+              
+    return (0);
+}
+int AT45::read_block(char *data, int block)  // under construction F&#65533;R CHECK AF MIC OG LERCHE
+{    
+    char temp_data[_pagesize];
+    int page_start;
+
+    if (block < _blocks || block == 0) {
+        page_start = block * 8;
+
+        for (int i=0; i<8; i++) {
+            read_page(temp_data, page_start);
+            //printf("%d Read round, Data is: %d\r\n",i,*temp_data);
+            page_start = page_start + 1;
+            for (int z=0; z<_pagesize ; z++) {
+                data[z+(_pagesize*i)] = temp_data[z];
+            }
+        }
+    } else {
+        //do nothing
+    }
+    //printf("Read done, Data is: %d\r\n",*data);
+    return (0);
+}
+     
+int AT45::read_block(char *data[], int block)       // under construction F&#65533; CHECK AF MIC OG LERCHE 
+{
+    char temp_data[_pagesize];
+    int page_start;
+    
+    if(block < _blocks || block == 0)   
+    {
+        page_start = block * 8;
+    
+        for(int i=0; i<8 ;i++)                         // 8 pages in a block
+        {
+            read_page(temp_data, page_start);
+            page_start = page_start + 1;
+            for(int z=0; z<_pagesize ;z++)
+            {
+                data[i][z] = temp_data[z];
+            }  
+        }
+    }
+    else
+    {
+        //do nothing   
+    }
+ 
+    return (0);
+}
+       
+// This function writes the char to the address supplied
+// Note : We pass the raw address to the underlying functions
+void AT45::write_byte(int address, char data) 
+{
+    _busy();   
+    _flashread(1,address);             // read the Flash page into SRAM buffer
+    _busy();                           // wait for the read to complete
+    _sramwrite(1,address,data);        // Write new data into SRAM
+    _busy();                           // Make sure flash isnt busy
+    _flashwrite(1,address);            // Write back to the page address
+}       
+      
+int AT45::write_page(char* data, int page)
+{
+    int address = -1;
+    
+    if(_pagesize == 256)
+    {
+        address = page * 256;
+    }
+    else if(_pagesize == 264)
+    {
+        address = page * 512;
+    }
+    else if(_pagesize == 512)
+    {
+        address = page * 512;
+    }
+    else if(_pagesize == 528)
+    {
+        address = page * 1024;
+    }
+    else if(_pagesize == 1024)
+    {
+        address = page * 1024;
+    }
+    else if(_pagesize == 1056)
+    {
+        address = page * 2048;
+    }
+    else 
+    {
+        return (-1); // something isnt configured right
+    }
+    
+    _select();
+    _spi.write(0x84); // writing to buffer #1
+    _sendaddr (0); // we are writing to the entire buffer
+
+    for(int i=0; i<_pagesize ;i++) 
+    {
+        _spi.write (data[i]);  
+    }
+    _deselect();        
+        
+    _busy(); // make sure the Flahs isnt busy
+                
+    // issue command to write buffer 1 to the appropraite flash page
+    _select();  
+    _spi.write (0x83);  
+    _sendaddr (_getpaddr(address));  
+    _deselect();
+    
+    return (0);   
+}
+int AT45::write_block(char *data, int block) // under construction F&#65533;R CHECK AF MIC OG LERCHE
+{    
+    
+    int page_start;
+    char page_arr[_pagesize];
+    
+    if (block < _blocks || block == 0) 
+    {
+        page_start = block * 8;
+        
+        for (int i=0; i<8 ; i++) 
+        {
+            // Copy data from *data at 0 to 511 _ 512 - 1023, and so on every round.  
+            memcpy(page_arr, &data[_pagesize*i], _pagesize); 
+            
+            write_page(page_arr, page_start);
+            page_start = page_start + 1;
+        }
+    } else {
+        //do nothing
+    }
+
+    return (0);
+}
+int AT45::write_block(char *data[], int block)      // under construction F&#65533; CHECK AF MIC OG LERCHE 
+{
+    char temp_data[_pagesize];
+    int page_start;
+    
+    if(block < _blocks || block == 0)   
+    {
+        page_start = block * 8;
+    
+        for(int i=0; i<8 ;i++) 
+        {
+            for(int z=0; z<_pagesize ;z++)
+            {
+               temp_data[z] = data[i][z];    
+            }   
+            write_page(temp_data, page_start);
+            page_start = page_start + 1;
+        }
+    }
+    else
+    {
+        //do nothing   
+    }
+ 
+    return (0);
+}
+
+int AT45::FAT_read(char* data, int page)          
+{
+    // For 256 byte pages, we read two pages
+    if((_pagesize == 256) || (_pagesize == 264)) 
+    {
+        int address = page * 512; // This is the start address of the 512 byte block
+           
+        _flashread(1,address); // read the first page of the block into SRAM buffer 1
+        _busy(); // Wait until First page has loaded into buffer 1
+        
+        // this is done directly as we are reading back an entire buffer, and this can be done more optimally than using _sramread
+        _select();
+        _spi.write(0xd4);
+        _sendaddr (0x0);
+        _spi.write (0x0);   // dont care byte
+        
+        for(int i=0;i<256;i++) 
+        {
+            data[i] = _spi.write (0x0);  
+        }
+        _deselect();            
+                
+        _flashread(1,address+256); // read the second page of the block into SRAM buffer 2
+        _busy(); // Wait until second page has loaded into buffer 2
+        
+        // Now the second page is loaded, pull this out into the second half of the data buffer
+        // this is done directly as we are reading back an entire buffer, and this can be done more optimally than using _sramread
+        _select();
+        _spi.write(0xd4);
+        _sendaddr (0x0);
+        _spi.write (0x0);   // dont care byte
+        
+        for(int i=0;i<256;i++) 
+        {
+            data[256+i] = _spi.write (0x0);  
+        }
+        _deselect();                
+        return (0);
+    }
+    
+    // For 512 byte pages, we read just the single page, transfer it    
+    else if((_pagesize == 512) || (_pagesize == 528)) 
+    {
+        int address = page * 512; // This is the start address of the 512 byte block
+    
+        _busy(); // Wait until First page has loaded into buffer 1
+        _flashread(1,address); // read the first page of the block into SRAM buffer 1
+        _busy(); // Wait until First page has loaded into buffer 1
+        
+        // Now the page has loaded, simply transfer it from the sram buffer to the data array
+        // this is done directly as we are reading back an entire buffer, and this can be done more optimally than using _sramread
+        _select();
+        _spi.write(0xd4);
+        _sendaddr (0x0);
+        _spi.write (0x0);   // dont care byte
+        
+        for(int i=0;i<512;i++) 
+        {
+            data[i] = _spi.write (0x0);  
+        }
+        _deselect();            
+        return (0);
+    }
+
+    // For 1024 byte pages, we read just a single page, transfer half of it
+    else if((_pagesize == 1024) || (_pagesize == 1056)) 
+    {
+        int address = _getpaddr(page * 512); // This is the start address of the 512 byte block
+
+        _busy(); // Wait until First page has loaded into buffer 1
+    
+        _flashread(1,address); // read the first page of the block into SRAM buffer 1
+
+        _busy(); // Wait until First page has loaded into buffer 1
+        
+        // Now the page has loaded, simply transfer it from the sram buffer to the data array
+        // this is done directly as we are reading back an entire buffer, and this can be done more optimally than using _sramread
+
+        _select();
+        _spi.write(0xd4);
+
+        if (page %2) // odd numbered block, read from adress 0x200
+        { 
+            _sendaddr (0x200);
+        }
+        else // even numbered block, then we are reading from sram buffer 0x0 
+        {
+            _sendaddr (0x0);
+        }
+
+        _spi.write (0x0);   // dont care byte
+        
+        for(int i=0;i<512;i++) 
+        {
+            data[i] = _spi.write (0x0);  
+        }
+        _deselect();            
+        return (0);
+    }
+    else 
+    {
+        return (-1); // something isnt configured right
+    }
+}
+       
+int AT45::FAT_write(char* data, int page)        
+{
+    // For 256 byte pages, we overwrite two pages
+    if((_pagesize == 256) || (_pagesize == 264))
+    {
+        
+        // fill the first buffer with the first half of the block
+        // do this directly, for better performance
+        _select();
+        _spi.write(0x84); // writing to buffer #1
+        _sendaddr (0); // we are writing to the entire buffer
+
+        for(int i=0;i<256;i++) {
+            _spi.write (data[i]);  
+        }
+        _deselect();        
+                
+        _flashwrite(1,(page*512));
+
+        // fill the buffer with the second half of the block
+        // do this directly, for better performance
+        _select();
+        _spi.write(0x84); // writing to buffer #1
+        _sendaddr (0); // we are writing to the entire buffer
+
+        for(int i=0;i<256;i++) {
+            _spi.write (data[256+i]);  
+        }
+        _deselect();        
+
+        _flashwrite(1,((page*512)+256));
+    }
+        
+    // For 512 byte pages, we overwrite a single page
+    else if((_pagesize == 512) || (_pagesize == 528)) 
+    {
+    
+        // fill the first buffer with the block data
+        // do this directly, for better performance
+        _select();
+        _spi.write(0x84); // writing to buffer #1
+        _sendaddr (0); // we are writing to the entire buffer
+
+        for(int i=0;i<512;i++) {
+            _spi.write (data[i]);  
+        }
+        _deselect();        
+        
+        _busy(); // make sure the Flahs isnt busy
+                
+        // issue command to write buffer 1 to the appropraite flash page
+        _select();  
+        _spi.write (0x83);  
+        _sendaddr (_getpaddr(page * 512));  
+        _deselect();                
+    }
+
+    // For 1024 byte pages, we do a read modify write
+    // must make sure we overwrite the right half of the page!
+    else if((_pagesize == 1024) || (_pagesize == 1056)) 
+    {
+
+        _busy(); // make sure the flash isnt busy
+
+        int address = _getpaddr(page*512);
+
+        // Read the page into sram
+        _flashread(1,address);  
+        
+        // wait for this operation to complete
+        _busy();
+        
+        // Overwrite the appropriate half
+        // do this directly, for better performance
+        _select();
+        _spi.write(0x84); // writing to buffer #1
+
+        if(page%2)  // this is an odd block number, overwrite second half of buffer 
+        {  
+            _sendaddr (0x200); // we are writing to the entire buffer
+        }
+        else        // this is an even block, overwrite the first half
+        {  
+            _sendaddr (0x0); // we are writing to the entire buffer
+        }
+
+        for(int i=0;i<512;i++) 
+        {
+            _spi.write (data[i]);  
+        }
+        _deselect();        
+        
+        // Write the page back
+        _busy();
+        _flashwrite(1,address); 
+    }
+    
+    // Something has gone wrong
+    else 
+    {
+        return (-1);
+    }
+    
+    return (0);
+}
+       
+// Erase the entire chip
+void AT45::chip_erase() 
+{ 
+    _busy(); // make sure flash isnt already in busy.
+
+    _select();
+    // 4 byte command sequence
+    _spi.write(0xc7);
+    _spi.write(0x94);
+    _spi.write(0x80);
+    _spi.write(0x9a);
+    _deselect();  
+
+    _busy(); // Make erase a blocking function
+}        
+
+// Erase one block  
+void AT45::block_erase(int block)      
+{
+    int address = -1;
+    
+    // Calculate page addresses
+    if(block < _blocks || block == 0)   
+    {
+        if(_pagesize == 256)
+        {
+            address = block * 2048;
+        }
+        else if(_pagesize == 264)
+        {
+            address = block * 4096;
+        }
+        else if(_pagesize == 512)
+        {
+            address = block * 4096;
+        }
+        else if(_pagesize == 528)
+        {
+            address = block * 8192;
+        }
+        else if(_pagesize == 1024)
+        {
+            address = block * 8192;
+        }
+        else if(_pagesize == 1056)
+        {
+            address = block * 16384;
+        }
+        
+        _busy();
+        _select();
+        _spi.write(0x50);
+        _sendaddr (address);
+        _deselect();
+        _busy();   
+    }
+    else
+    {
+        //do nothing   
+    }
+}
+
+// Erase one page       
+void AT45::page_erase(int page)
+{
+    int address = -1;
+    
+    // Calculate page addresses
+    if(page < _pages || page == 0)   
+    {
+        if(_pagesize == 256)
+        {
+            address = page * 256;
+        }
+        else if(_pagesize == 264)
+        {
+            address = page * 512;
+        }
+        else if(_pagesize == 512)
+        {
+            address = page * 512;
+        }
+        else if(_pagesize == 528)
+        {
+            address = page * 1024;
+        }
+        else if(_pagesize == 1024)
+        {
+            address = page * 1024;
+        }
+        else if(_pagesize == 1056)
+        {
+            address = page * 2048;
+        }
+        
+        _busy();
+        _select();
+        _spi.write(0x81);
+        _sendaddr (address);
+        _deselect();
+        _busy();   
+    }
+    else
+    {
+        //do nothing   
+    }
+}
+      
+// return the size of the part in bytes
+int AT45::device_size() 
+{ 
+    return _devicesize;
+}       
+
+// return the numbers of pages
+int AT45::pages() 
+{ 
+    return _pages;
+}       
+       
+// return the page size of the part in bytes
+int AT45::pagesize() 
+{ 
+    return _pagesize;
+}       
+       
+// A one-time programmable configuration
+void AT45::set_pageszie_to_binary()
+{
+    _busy(); // make sure flash isnt already in busy.
+
+    _select();
+    // 4 byte command sequence
+    _spi.write(0x3d);
+    _spi.write(0x2a);
+    _spi.write(0x80);
+    _spi.write(0xa6);
+    _deselect();  
+
+    _busy(); // Make erase a blocking function   
+}
+
+// Return the number of blocks in this device in accordance with the datasheet
+int AT45::blocks() 
+{  
+    return _blocks;
+}
+       
+// Return the Id of the part
+int AT45::id() 
+{ 
+    int id = 0;
+    _select();
+    _spi.write(0x9f);
+    id = (_spi.write(0x00) << 8);
+    id |= _spi.write(0x00);
+    _deselect();            
+    return id; 
+}
+         
+// return the Status
+int AT45::status() 
+{ 
+    int status = 0;
+    _select();
+    _spi.write(0xd7);
+    status = (_spi.write(0x00));
+    _deselect();            
+    return status; 
+}
+          
+// Make sure the Flash isnt already doing something
+void AT45::busy() 
+{
+    _busy();
+}
+
+void AT45::deep_power_down(bool _deep_down_onoff) 
+{
+    if(_deep_down_onoff == false) // Wake up from deep power down
+    {
+        _select();
+        _spi.write(0xab);
+        _deselect();
+        _deep_down = true;
+        // remenber to want 35uS before using the device.          
+    }
+    else if(_deep_down_onoff == true) // Go to deep power down
+    {
+        _busy();
+        _select();
+        _spi.write(0xb9);
+        _deselect();
+        _deep_down = false;
+    }
+    else
+    {
+        //do nothing   
+    }       
+}
+
+void AT45::ultra_deep_power_down(bool _deep_down_onoff) 
+{
+    if(_deep_down_onoff == false) // Wake up from deep power down
+    {
+        _select();
+        //_spi.write(0xab);
+                //wait 20ns
+                nrf_delay_us(1);
+        _deselect();
+        _deep_down = true;
+        // remenber to want 35uS before using the device.          
+    }
+    else if(_deep_down_onoff == true) // Go to deep power down
+    {
+        _busy();
+        _select();
+        _spi.write(0x79);
+        _deselect();
+        _deep_down = false;
+    }
+    else
+    {
+        //do nothing   
+    }       
+}
+
+bool AT45::is_it_awake()
+{
+    return _deep_down;
+}
+
+//=============================================================================
+// Private functions
+//=============================================================================
+
+void AT45::_initialize()
+{
+    int _id = 0;
+    int _status = 0;
+  
+    _id = id();
+    _id = id();
+    _status = status();
+    
+    if ((_id & 0x1f) == 0x3)  // 2Mbits 
+    { 
+        _devicesize = 262144; // Size in bytes
+        _pages = 1024;        // Number of pages
+        _blocks = 128;        // Number of blocks
+        if (_status & 0x1) 
+        {
+            _pagesize = 256;
+        }
+        else 
+        {
+            _pagesize = 264;
+        }    
+    }
+    else if ( (_id & 0x1f) == 0x4) // 4Mbits 
+    { 
+        _devicesize = 524288;
+        _pages = 2048;
+        _blocks = 256;        
+        if (_status & 0x1) 
+        {
+            _pagesize = 256;
+        }
+        else 
+        {
+            _pagesize = 264;
+        }    
+    }
+    else if ( (_id & 0x1f) == 0x5) // 8Mbits 
+    { 
+        _devicesize = 1048576;
+        _pages = 4096;
+        _blocks = 512;        
+        if (_status & 0x1) 
+        {
+            _pagesize = 256;
+        }
+        else 
+        {
+            _pagesize = 264;
+        }    
+    }
+    else if ( (_id & 0x1f) == 0x6) // 16Mbits 
+    { 
+        _devicesize = 2097152;
+        _pages = 4096;
+        _blocks = 512;        
+        if (_status & 0x1) 
+        {
+            _pagesize = 512;
+        }
+        else 
+        {
+            _pagesize = 528;
+        }
+    }
+    else if ( (_id & 0x1f) == 0x7) // 32Mbits 
+    { 
+        _devicesize = 4194304;
+        _pages = 8192;
+        _blocks = 1024;        
+        if (_status & 0x1) 
+        {
+            _pagesize = 512;
+        }
+        else 
+        {
+            _pagesize = 528;
+        }
+    }
+    else if ( (_id & 0x1f) == 0x8) // 64Mbits 
+    { 
+        _devicesize = 8388608;
+        _pages = 8192;
+        _blocks = 1024;
+        if (_status & 0x1) 
+        {
+            _pagesize = 1024;
+        }
+        else 
+        {
+            _pagesize = 1056;
+        }
+    }
+    else 
+    {
+        _devicesize = -1;
+        _pages = -1;
+        _pagesize = -1;
+        _blocks = -1;
+    }
+}
+
+void AT45::_select()
+{
+    _ncs = 0;    
+}
+
+void AT45::_deselect()
+{
+    _ncs = 1;
+}
+
+void AT45::_busy() {
+    volatile int iambusy = 1;  
+    while (iambusy) {
+        // if bit 7 is set, we can proceed
+        if ( status() & 0x80 ) {
+            iambusy = 0;}
+    }
+}
+
+// Write to an SRAM buffer
+// Note : We create buffer and page addresses in _sram and _flash        
+void AT45::_sramwrite(int buffer, int address, int data)
+{
+
+    int cmd = 0;
+    int baddr = 0;
+  
+    baddr = _getbaddr(address);
+  
+    _busy();
+  
+    _select();
+  
+    if (buffer == 1) 
+        {cmd = 0x84;}
+    else 
+        {cmd = 0x87;}
+
+    _spi.write(cmd);
+    _sendaddr (baddr);
+    _spi.write (data);  
+
+    _deselect();            
+}
+
+// Read from an SRAM buffer
+// Note : We create buffer and page addresses in _sram and _flash
+int AT45::_sramread(int buffer, int address) 
+{
+
+    int cmd = 0;
+    int baddr = 0;
+    int bufdata = 0;
+  
+    baddr = _getbaddr(address);
+  
+    _select();
+  
+    if(buffer == 1) 
+        {cmd = 0xd4;}
+    else 
+        {cmd = 0xd6;}
+  
+    _spi.write(cmd);
+    _sendaddr (baddr);
+    _spi.write (0x0);   // dont care byte
+    bufdata = _spi.write (0x0);  
+  
+    _deselect();            
+ 
+    return (bufdata);
+}
+
+// Write and SRAM buffer to main memory
+void AT45::_flashwrite (int buffer, int address)
+{
+
+    int cmd = 0;
+    int paddr = _getpaddr(address);
+ 
+    _busy();  // Check flash is not busy 
+    
+    _select();  
+
+    if (buffer == 1) 
+        {cmd = 0x83;}
+    else 
+        {cmd = 0x86;}
+      
+    _spi.write (cmd);  
+    _sendaddr (paddr);  
+    _deselect();     
+
+    _busy();  // Check flash is not busy 
+}
+
+// Read from Flash memory into SRAM buffer
+void AT45::_flashread (int buffer, int address) 
+{
+
+    int cmd = 0;
+    int paddr = _getpaddr(address); // calculate page address
+  
+    _busy();  // Check flash is not busy
+    _select();
+      
+    if (buffer == 1)
+        {cmd = 0x53;}
+    else
+        {cmd = 0x55;}
+
+    _spi.write (cmd);  
+    _sendaddr (paddr);
+    _deselect();            
+}
+
+// Read directly from main memory
+int AT45::_memread (int address) 
+{
+
+    int data = 0;        
+    int addr;
+
+    addr = _getpaddr(address) | _getbaddr(address);
+
+    _busy();
+
+    _select();
+
+    _spi.write (0xd2);  // Direct read command
+    _sendaddr (addr);
+  
+    // 4 dont care bytes
+    _spi.write (0x00);  
+    _spi.write (0x00);  
+    _spi.write (0x00);  
+    _spi.write (0x00);  
+  
+    // this one clocks the data
+    data = _spi.write (0x00);  
+    _deselect();            
+
+    _busy();
+
+    return data;
+}
+
+// Work out the page address
+// If we have a 2^N page size, it is just the top N bits
+// If we have non-2^N, we use the shifted address
+int AT45::_getpaddr(int address) 
+{
+
+    int paddr;
+
+    if (_pagesize == 256) {                 
+        paddr = address & 0xffffff00;}    
+    else if (_pagesize == 264) {                 
+        paddr = (address << 1) & 0xfffffe00;}
+    else if (_pagesize == 512) {                 
+        paddr = address & 0xfffffe00;}
+    else if (_pagesize == 528 ) {           
+       paddr = (address << 1) & 0xfffffc00;}
+    else if (_pagesize == 1024) {                 
+       paddr = address & 0xfffffc00;}
+    else if (_pagesize == 1056 ) {           
+        paddr = (address << 1) & 0xfffff800;}
+    else {
+        paddr = -1;}
+    
+    return (paddr);
+}
+
+// Clean the buffer address. This is the 8/9/10 LSBs
+int AT45::_getbaddr(int address) 
+{
+
+    int baddr;
+
+    if ((_pagesize == 256) || (_pagesize == 264 )) {
+        baddr = address & 0xff;}
+    else if ((_pagesize == 512) || (_pagesize == 528 )) {
+        baddr = address & 0x1ff;}
+    else if ((_pagesize == 1024) || (_pagesize == 1056 )) {
+        baddr = address & 0x3ff;}
+    else {
+        baddr = -1;}
+
+    return (baddr);
+}
+
+// Sends the three lest significant bytes of the supplied address
+void AT45::_sendaddr (int address) 
+{
+    _spi.write(address >> 16);
+    _spi.write(address >> 8);
+    _spi.write(address);      
+}
\ No newline at end of file