' {$STAMP BS2sx}
' {$PBASIC 2.5}
' {$PORT COM5}
' Purpose...Write a 12 bit word to a 24LC128 EEPROM
'
' =========================================================================
'
' -------------------------------------------------------------------------
' Program Description
' -------------------------------------------------------------------------
'
'WRITE a 12 bit word via a subroutine to a 24LC128 EEPROM address,
'starting at 1, incrementing by 2 and ending at address 4095.
'Flash an LED ON/OFF to confirm each WRITE cycle.
'
' -------------------------------------------------------------------------
'
'------[ I/O Definitions ]--------------------------------------
LED PIN 4
SDA PIN 5 ' I2C Serial Data Line
SCL PIN 6 ' I2C Serial Clock Line
' -----[ Constants ]-------------------------------------------------------
Address CON $A0 ' Address Of 24LC128
Ack CON 0 ' Acknowledge Bit
' -----[ Variables ]-------------------------------------------------------
temp VAR Word ' Variable Used For Work
i2cWork VAR Word ' Work Byte For I2C I/O
i2cWork1 VAR Word ' Work Byte For I2C I/O
i2cWork2 VAR Word ' Work Byte For I2C I/O
i2cAck VAR Bit ' Ack Bit From Device
eeprom_add VAR Word ' EEPROM Address
J     VAR         Nib
' -----[ Main Routine ]----------------------------------------------------
FOR temp = 1 TO 4095 STEP 2
  eeprom_add = temp
  GOSUB WriteEE
NEXT 'temp
END
' -----[ Subroutines ]-----------------------------------------------------
  ' Writing Section
WriteEE:
FOR J = 1 TO 2
  GOSUB I2C_Start
  GOSUB Control_Byte_Write
  GOSUB Addrs
  GOSUB I2C_Write
  GOSUB I2C_Stop
  PAUSE 3
NEXT 'J
RETURN

I2C_Stop: ' I2C Stop Bit Sequence
LOW SDA
INPUT SCL
INPUT SDA ' SDA --> High While SCL High
RETURN

I2C_Start: ' I2C Start Bit Sequence
INPUT SDA
INPUT SCL
LOW SDA ' SDA --> Low While SCL High
RETURN

Control_Byte_Write: ' I2C Control Write Byte Sequence
i2cWork = Address
i2cWork.BIT0 = 0 ' Sets Unit To Write
SHIFTOUT SDA, SCL, MSBFIRST, [i2cWork\8] ' Send Byte To Device
SHIFTIN SDA, SCL, MSBPRE, [i2cAck\1] ' Get Acknowledge Bit
RETURN

Addrs: ' I2C Address Byte Sequence
i2cWork = eeprom_add  + J - 1
SHIFTOUT SDA, SCL, MSBFIRST, [i2cWork.HIGHBYTE\8] ' Send Byte To Device
SHIFTIN SDA, SCL, MSBPRE, [i2cAck\1] ' Get Acknowledge Bit
SHIFTOUT SDA, SCL, MSBFIRST, [i2cWork.LOWBYTE\8] ' Send Byte To Device
SHIFTIN SDA, SCL, MSBPRE, [i2cAck\1] ' Get Acknowledge Bit
RETURN

I2C_Write: ' I2C Write 2 Byte Sequence
IF J =1 THEN
  i2cWork = temp.LOWBYTE
  HIGH LED
SHIFTOUT SDA, SCL, MSBFIRST, [i2cWork\8] 'Send 8 bits (1 byte) To Device
ELSE
  i2cWork = temp.Nib2
  LOW LED
  DEBUG "temp.NIB2= ",temp.NIB2,CR
SHIFTOUT SDA, SCL, MSBFIRST, [i2cWork\4] 'Send 4 bits To Device
ENDIF
SHIFTIN SDA, SCL, MSBPRE, [i2cAck\1] ' Get Acknowledge Bit
RETURN

Control_Byte_Read: ' I2C Control Read Byte Sequence
i2cWork = Address
i2cWork.BIT0 = 1 ' Sets Device To Read
SHIFTOUT SDA, SCL, MSBFIRST, [i2cWork\8] ' Send Byte To Device
SHIFTIN SDA, SCL, MSBPRE, [i2cAck\1] ' Get Acknowledge Bit
RETURN 