'The ATTiny2313 is used.
'
'Charlos Potma PA3CKR
'
'20070220 v00 basic functionality
'20070222 v01 test i2c error
'
'Program reads four lm type temperature sensors.
'Temperature is displayed on a LCD and sent to a RS-232 i/f.
'The temperature string sent is completed with a four character hex crc.
'The companion program reads the temperature string and displays
'these on a graphical display.
'
$regfile = "ATtiny2313.DAT"
$crystal = 4000000
$baud = 9600

'Config LCD
Config Lcd = 16 * 2
Config Lcdpin = Pin , Db4 = Portb.4 , Db5 = Portb.5 , Db6 = Portb.6 , Db7 = Portb.7 , E = Portb.3 , Rs = Portb.2

Config Pind.6 = Output
Led Alias Portd.6

Config Sda = Portd.5
Config Scl = Portd.4
'Rather slow I2C speed
Config I2cdelay = 20
'LM76 I2C write address
'Const Lm76xwrite = &H90 (not used)
'LM76 I2C read addresses
Const Lm761read = &H91
Const Lm762read = &H93
Const Lm763read = &H95
Const Lm764read = &H97
'LM76 resolution in degrees celcius
Const Lm76resolution = 625

Dim Tempint As Long
Dim Temptmp As Long
Dim Tempbytelo As Byte
Dim Tempbytehi As Byte
Dim Tempsign As Byte
Dim Tempstr As String * 7
Dim Outstr As String * 7
Dim Strl As Byte
Dim Strp As Byte
Dim Lmaddr As Byte
Dim Crc As Byte
Dim Crchexstr As String * 4
Dim Crctot As Word

'Measure temperature
Declare Sub Readtemp
'make temperature string
Declare Sub Makeoutstr


Cls
Lcd "cpjp multitemp"
Wait 1

Do
  Crctot = 0
  Set Led
  Wait 1
  Reset Led
  'sensor 1
  Lmaddr = Lm761read
  Call Readtemp
  Call Makeoutstr
  Print Outstr;
  Crc = Crc8(outstr , 7)
  Crctot = Crctot + Crc
  Cls
  Lcd Outstr
  'sensor 2
  Lmaddr = Lm762read
  Call Readtemp
  Call Makeoutstr
  Print Outstr;
  Crc = Crc8(outstr , 7)
  Crctot = Crctot + Crc
  Locate 1 , 8
  Lcd Outstr
  'sensor 3
  Lmaddr = Lm763read
  Call Readtemp
  Call Makeoutstr
  Print Outstr;
  Crc = Crc8(outstr , 7)
  Crctot = Crctot + Crc
  Locate 2 , 1
  Lcd Outstr
  'sensor 4
  Lmaddr = Lm764read
  Call Readtemp
  Call Makeoutstr
  Print Outstr;
  Crc = Crc8(outstr , 7)
  Crctot = Crctot + Crc
  Crchexstr = Hex(crctot)
  Print Crchexstr
  Locate 2 , 8
  Lcd Outstr
  Wait 1
Loop

Sub Readtemp
'Read the two temperature bytes in two's complement
  I2cstart
  I2cwbyte Lmaddr
  I2crbyte Tempbytehi , Ack
  I2crbyte Tempbytelo , Nack
  I2cstop
  'Calculate temperature
  Tempint = Makeint(tempbytelo , Tempbytehi)
  Tempsign = Tempbytehi And 128
  If Tempsign = 128 Then
    Tempint = Not Tempint
    Tempint = Tempint + 1
  End If
  Shift Tempint , Right , 3
  Tempint = Tempint * Lm76resolution
  Tempint = Tempint / 1000
End Sub

Sub Makeoutstr
  'Make output string for one temperature
  If Err = 0 Then
    Temptmp = Tempint / 10
    Temptmp = Temptmp * 10
    Temptmp = Tempint - Temptmp
    Tempint = Tempint / 10
    Tempstr = Str(tempint)
    Strl = Len(tempstr)
    Strp = -strl
    Strp = Strp + 6
    Outstr = "     . "
    Mid(outstr , Strp , Strl) = Tempstr
    Tempstr = Str(temptmp)
    Mid(outstr , 7 , 1) = Tempstr
  Else
    'fill string with - after i2c error (sensor not attached?)
    Outstr = "-------"
  End If
End Sub

End