Problem writing to 64k EEPROM

Comments

• Mike Green Posts: 23,101

  2012-06-19 21:31 edited 2012-06-19 21:31

  Your code looks ok. The only thing I could think of that would behave the way you describe would that the bytes from $FFF8 to $FFFB won't program for some reason. The erased state of the EEPROM is all one bits, so they would be read as -1. One easy way to tell would be to change all your addresses from $FFEx and $FFFx to $FFCx and $FFDx, then see what happens.
• Peter Jakacki Posts: 10,193

  2012-06-19 21:35 edited 2012-06-19 21:35

  This method of having to specify a fixed address for a variable in EEPROM is redundant as Spin variables are embedded within the image that is loaded from EEPROM on boot, all you need to do is to modify that variable at it's location in EEPROM and automatically it is loaded on boot. Where's that location? Not a mystery. Use i2c.WriteLong(@myvariable,myvariable) to change the default variable and it will automatically be restored at boot.
• msrobots Posts: 3,709

  2012-06-19 21:41 edited 2012-06-19 21:41

  Hi Peter,
  
  you got me there - this is brilliant simple. Never thought of it. I really like it.
  
  Thank you
  
  Mike
• MJHanagan Posts: 189

  2012-06-20 04:00 edited 2012-06-20 04:00

  I fiddled with the code and it turns out I was using the "i2c.WaitWrite" routine incorrectly. I assumed it returned one the current write operation was complete but this is not the case. It immediately returns a value of 1 (if the EEPROM is busy - like still writing) or a 0 when the write operation is completed. Once I put in the

  REPEAT UNTIL i2c.WriteWait(i2c#BootPin, i2c#EEPROM, Addr ) == 0
  

  line it now waits for the write operation to complete before the read occurs so now it works fine. It seems the write operation takes a whopping 5 msec to complete (much, much slower than I expected).
  

  CON
    _clkmode = xtal1 + pll16x
    _xinfreq = 5_000_000
  
  OBJ
    i2c : "Basic_I2C_Driver"
    pst : "Parallax Serial Terminal"
        
  PUB initialize | EEPROM, Addr, StepAddr
  
      pst.Start( 115200 )                       
      pst.Clear
      pst.Beep
  
      StepAddr := 4
      Addr := $FFFF - 3  
       
      REPEAT 20
       
        pst.str(string( pst#nl, "Addr: $"))
        pst.hex( Addr, 4 )
         
        EEPROM := i2c.ReadLong(i2c#BootPin, i2c#EEPROM, Addr )
        pst.str(string( "  Initial read: $"))
        pst.hex( EEPROM, 4 )
         
        pst.str(string( "  Writing: "))
        pst.hex( Addr, 4 )
         
        i2c.WriteLong(i2c#BootPin, i2c#EEPROM, Addr, Addr )
        ' used to be: i2c.WriteWait(i2c#BootPin, i2c#EEPROM, Addr )
        REPEAT UNTIL i2c.WriteWait(i2c#BootPin, i2c#EEPROM, Addr ) == 0
         
        EEPROM := i2c.ReadLong(i2c#BootPin, i2c#EEPROM, Addr )
        pst.str(string( "  After write: "))
        pst.hex( EEPROM, 4 )
       
        Addr -=StepAddr
         
  
        
    pst.str(String(pst#NL, pst#NL, "All done." ) )
  
  

  
  to this:
  

  
  and now everything is working as expected.
  
  If the write operation is busy this routine returns a value of 1. When the write operation is done it returns a value of 0.
• MJHanagan Posts: 189

  2012-06-20 04:06 edited 2012-06-20 04:06

  I need to store a few values in EEPROM so they doen't get over written when Spin load new code into the EEPROM. Since the lower 32k are for Spin I am using location in the upper 32k range. So I assume the i2c.WriteLong(@myvariable,myvariable) won't work here since no variable could have an address greater than $7FFF. Is that correct?
• Mike Green Posts: 23,101

  2012-06-20 05:18 edited 2012-06-20 05:18

  The "trick" that Peter mentioned won't work when the Propeller Tool downloads new code into the EEPROM. You'll have to use EEPROM past 32K for that as you're doing.
• MJHanagan Posts: 189

  2012-06-20 08:09 edited 2012-06-20 08:09

  Thanks for the help with this little problem!