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MODULE EEPROM8K;
(* =========================================================================  
   Example Cortex-M3 Oberon Program  
 
   Description:
     Read / Writes a string and an integer to EEPROM via I2C bus
      
   Target: 
     LPC17xx systems with a 8 kbit EEPROM e.g. MicroChip 24LC64
     connected to the I2C bus

   Tested on:
     Embedded Artists LPCXpresso LPC1769
     (I2C1, P0.19 = SDA1, P0.20 = SCL1)
     
   Refs: 
     NXP LPC17xx User Manual UM10360
     MicroChip 24AA64/24LC64/24FC64 Datasheet
     Oberon for Cortex-M3 Microcontrollers
   
   (c) 2010-2012 CFB Software   
   http://www.astrobe.com  
   
   ========================================================================= *)

IMPORT I2C, MCU, Main, Out, SYSTEM;


PROCEDURE Progress(msg: ARRAY OF CHAR; status: INTEGER);
BEGIN
  Out.String(msg); 
  IF status = I2C.OK THEN 
    Out.String(" OK"); Out.Ln()
  ELSE 
    Out.String(" Error "); Out.Int(status, 0); Out.Ln();
    (* Terminate the program *)
    ASSERT(FALSE)
  END
END Progress;


PROCEDURE* SwapLowBytes(word: INTEGER): INTEGER;
BEGIN
  RETURN LSR(LSL(word, 24), 16) + LSR(word, 8)
END SwapLowBytes;


PROCEDURE Read(EepromAddr, addr: INTEGER; VAR data: ARRAY OF SYSTEM.BYTE): INTEGER;
BEGIN
  RETURN I2C.ReadBytes(EepromAddr, addr, 2, data, 0, LEN(data))
END Read;  


PROCEDURE Write(EepromAddr, addr: INTEGER; data: ARRAY OF SYSTEM.BYTE): INTEGER;
BEGIN
  RETURN I2C.WriteBytes(EepromAddr, addr, 2, data, 0, LEN(data))
END Write;  


PROCEDURE Run;
CONST
  (* I2C1, P0.19 = SDA1, P0.20 = SCL1 *) 
  I2CBus = 3;
  (* 7-bit Slave address. Ref: 24LC64 *) 
  EepromAddr = 050H;
VAR 
  id, idRead: ARRAY 8 OF CHAR;
  idAddr, counterAddr : INTEGER;
  status, counter: INTEGER;
BEGIN
  I2C.Init(I2CBus, 400000);
  id := "Astrobe";
  idAddr := 0;
  (* MSB is byte[0], LSB is byte[1] *)
  counterAddr := SwapLowBytes(idAddr + LEN(id));

  status := I2C.OK;
  Progress("EEPROM", status);

  (* Look for the id in the EEPROM to see if it has been written previously *)
  status := Read(EepromAddr, idAddr, idRead);
  Progress("Read ID", status);
  Out.Char(22X); Out.String(idRead); Out.Char(22X); Out.Ln();
  IF idRead # id THEN 
    (* No id yet. Write it and initialise the counter *)
    status := Write(EepromAddr, idAddr, id); 
    Progress("Write ID", status);
    status := I2C.Ready(EepromAddr);
    Progress("Ready", status);
    counter := 0
  ELSE
    Out.String(idRead); Out.Ln();
    status := Read(EepromAddr, counterAddr, counter);
    Progress("Read counter", status)
  END;
  Out.Int(counter, 8); Out.Ln();
  INC(counter);
  status := Write(EepromAddr, counterAddr, counter);
  Progress("Write counter", status)
END Run;

BEGIN
  Run()
END EEPROM8K.