Quelltext der Seite EEPROM Wear Leveling (AVR101)

== Overview ==
This is an implementation of the algorithm described in the [http://www.atmel.com/Images/doc2526.pdf Appnote AVR101] by Atmel. Its purpose is to increase the write cycles for parameters in EEPROM.

To achieve this, there are two ring buffers for each parameter: a status buffer, which keeps track of the last written index and the parameter buffer itself.
Because the write cycles are distributed over several EEPROM cells, the life time is increased.

== Usage ==
Include the library at the top of your program:
<pre>Const Wearlevel_count = [PARAMETER COUNT]                    ' number of parameters to store in eeprom (default: 1)
' ring buffer size (estimated life time: 100.000 cell write cycles * wearlevel depth)
'Const Wearlevel_depth = [BUFFER_SIZE]                       ' uncomment to define the buffer sizes (default: 8)
'Const Wearlevel_start = [EEPROM_START]                      ' uncomment to set EEPROM start address (default: 1)
$include "wear_leveling.inc"</pre>

Define the parameters stored in EEPROM and link them to a SRAM variable:
<pre>Dim My_parameter As [TYPE]
Wearlevel_pointer([PARAMETER_ID]) = Varptr(My_parameter)     ' address of variable in SRAM
Wearlevel_size([PARAMETER_ID]) = [TYPE_SIZE]                 ' byte size of the variable data type</pre>

Load all parameters stored in EEPROM:
<pre>Wearlevel_read 0</pre>

Load specific parameter with ID:
<pre>Wearlevel_read [PARAMETER_ID]</pre>

Save all parameters to EEPROM:
<pre>Wearlevel_write 0</pre>

Save specific parameter with ID:
<pre>Wearlevel_write [PARAMETER_ID]</pre>

== Sample ==
<pre>$regfile = "m32def.dat"
$crystal = 16000000
$baud = 57600
$framesize = 48

Const Wearlevel_count = 3                                   ' number of parameters to store in eeprom (default: 1)
' ring buffer size (estimated life time: 100.000 cell write cycles * wearlevel depth)
'Const Wearlevel_depth = 10                                  ' uncomment to define the buffer sizes (default: 8)
'Const Wearlevel_start = 20                                  ' uncomment to set EEPROM start address (default: 1)
$include "wear_leveling.inc"

' define the parameters
Dim Testbyte As Byte
Wearlevel_pointer(1) = Varptr(testbyte)                     ' address of variable in SRAM
Wearlevel_size(1) = 1                                       ' byte size of the variable data type

Dim Testword As Word
Wearlevel_pointer(2) = Varptr(testword)
Wearlevel_size(2) = 2

Dim Testsingle As Single
Wearlevel_pointer(3) = Varptr(testsingle)
Wearlevel_size(3) = 4

' load all parameter values stored in EEPROM (ID = 0), called usually during the initialisation
Wearlevel_read 0
Print "READ 0: [1] " ; Testbyte ; ", [2] " ; Testword ; ", [3] " ; Testsingle

' assign some random values
Gosub Random_values
Print "RANDOM: [1] " ; Testbyte ; ", [2] " ; Testword ; ", [3] " ; Testsingle

' just save paramter 2 (Testword)
Wearlevel_write 2
Print "WRITE 2"

' load all again
Wearlevel_read 0
Print "READ 0: [1] " ; Testbyte ; ", [2] " ; Testword ; ", [3] " ; Testsingle

' new random values
Gosub Random_values
Print "RANDOM: [1] " ; Testbyte ; ", [2] " ; Testword ; ", [3] " ; Testsingle
' save all parameters (ID = 0)
Wearlevel_write 0
Print "WRITE 0"
End

Random_values:
   Testbyte = Rnd(255)
   Testword = Rnd(65535)
   Testsingle = Testword
   Testsingle = Testsingle / 1000
   Testword = Rnd(65535)
Return</pre>

== Download ==
[http://www.braunecker.at/downloads/wear_leveling_1_0.zip Download]