' MLX90614_05.Bas	
' I2C protocol code (c)2011 by PH Anderson and used with permission
' Please visit www.phanderson.com
' (c)2011 by MR Burnette for all rights not reserved by PH Anderson
' 
' Output of PICAXE is serial and intended for PC use
' Expands on _04 version by not reading the RAM $06
' 255 bytes / 4096
' PICAXE-20X2 directly connected to               
' MLX90614ESF-AAA is I2C protocol IR sensor with 0.02 degree Kevin accuracy
' Refer to product note section 8.7.2 for how temperature is converted from RAM reading
' Term 11 SCL --------------- SCL
' Term 13 SDA --------------- SDA

' PICAXE Compiler directives
#picaxe 20x2
#Terminal 2400
#No_Table
#No_Data
#freq m4	'Defined in code for Serial Output in SYMBOL table

' SYMBOL table - aliases
SYMBOL Lo 		= B0	' B1-B0 overmapped by W0 & bit0 - bit 7
SYMBOL Hi 		= B1
SYMBOL PEC 		= B2	' B3-B2 overmapped by W1 & bit8 - bit15
SYMBOL Status 	= B3
SYMBOL ______b4 	= B4	' B5-B4 overmapped by W2 & bit16 - bit31
SYMBOL ______b5 	= B5
SYMBOL ______b6 	= B6	' B7-B6 overmapped by W3
SYMBOL ______b7 	= B7
SYMBOL ______b8 	= B8	' B9-B8 overmapped by W4
SYMBOL ______b9 	= B9
SYMBOL SlaveAdr_2 = B10	' B11-10 overmapped by W5
SYMBOL RamLocation= B11
SYMBOL X 		= B12	' B13-B12 overmapped by W6
SYMBOL N 		= B13
SYMBOL CRC8 	= B14	' B15-B14 overmapped by W7
SYMBOL ______b15 	= B15
SYMBOL ______b16 	= B16	' B17-B16 overmapped by W8
SYMBOL ______b17 	= B17
SYMBOL ______b18 	= B18	' B19-B18 overmapped by W9
SYMBOL ______b19 	= B19
SYMBOL Val 		= W10	' W10 overwrites B20 - B21
SYMBOL TC_100 	= W11	' W11 overwrites B22 - B23
SYMBOL MLX90614ESF= W12	' W12 overwrites B24 - B25
' Note CLOCK & BAUD are related and must change together
' Default for the 20X2 chip is 8MHz
SYMBOL CLOCK = m4
SYMBOL BAUD = N2400_4
SYMBOL Serial = A.0

' Set frequency to CLOCK value since different than the 8MHz default
setfreq CLOCK

' Send startup message to serial port
serout Serial,BAUD,("Beginning data:",CR,LF)

INITIALIZE:
' Initialize I2C interface for MLX90614
' I2C code (c) by P.H. Anderson - Thanks Professor
' Return to this section on error condition on I2C bus CRC
    Hi2cSetup I2CMaster, 45, I2CSlow, I2CByte

' Setting values to 0 is only a formality as all PIC values are 0 on power-up
' General slave adr as only one device to read on IC2 bus
SlaveAdr_2 = $00 * 2


Again:
    ' RAM location $06 is the chip die temperature
    ' MLX90614ESF is set for display use
    ' RamLocation = $06
    ' GoSub ReadRAM	' Return Val (2 Byte word value)
    ' If Status = 0 Then Error	'Based on CRC algorithm
    ' MLX90614ESF = Val
    
    ' RAM location $07 is the object temperature in Kevin * 50 (0.02K resolution)
    RamLocation = $07
    GoSub ReadRAM
    If Status = 0 Then Error
    Val = Val/5	' integer divide by 5 to assist in smoothing
    ' If here then a Val word was returned for tObject and tAmbient is in var MLX90614ESF
    GoSub Display
    Pause 390	
    ' Pause 265	' At 2400 BAUD, 265ms results in a approx 1 second per reading
    ' 865ms total is required for the MLX90614 to fully settle before next reading
    GoTo Again

ReadRAM:
    Hi2cin [SlaveAdr_2], RamLocation, (Lo, Hi, PEC)
    Val = Hi
    Val = Val * 256 + Lo	' bitshift and combine
    'SerTxD ("DB ", #Hi,"-",#Lo,"-",#Val, CR, LF)
    CRC8 = $00
    X = SlaveAdr_2	: GoSub CalcCRC8
    X = RamLocation	: GoSub CalcCRC8
    X = SlaveAdr_2 + 1	: GoSub CalcCRC8
    X = Lo			: GoSub CalcCRC8
    X = Hi			: GoSub CalcCRC8
    X = PEC			: GoSub CalcCRC8
    '
    If CRC8 = 0 Then
       Status = 1 ' True is good
    Else
       Status = 0
    Endif
  
    Return


CalcCRC8:
   X = X ^ CRC8
   For N = 0 to 7
      If X > 127 Then
         X = X * 2
         X = X ^ $07
      Else
         X = X * 2
      Endif
   Next
   CRC8 = X
   Return


Display:
	' Serout Serial, BAUD, (#MLX90614ESF,", ",#Val,CR,LF)
	Serout Serial, BAUD, (#Val,CR,LF)
      Return
   	

Error:
	If RamLocation = $06 then
   		Serout Serial,BAUD,("T_A Error...", CR,LF)
   	else
   		Serout Serial,BAUD,("T_S Error...", CR,LF)
   	endif
   	Goto INITIALIZE
   
   
END