Hello,
I translated a CCBasic program I wrote into a Bascom 8051 program.
The CCBasic version works pervectly, I have not been able to test the Bascom 8051 version yet.
I think with a few modifications the Bascom 8051 program should work on a AVR.
Greetings,
Windt H.J.

Code:
'***************************************'
'* WINDT SYSTEMS                       *'
'* DS1621 v1.0 for 89S8252 Flash Board *'
'* 2006 / H.J. WINDT                   *'
'***************************************'
'----------------------------------------------------------------------------------------------------'
'This software for the 89S8252 will read the DS1621 9 bit Temperature'
'-55°C to +125°C in 0.5°C increments and display the data on a terminal program as T = xxx,x°C.'
'The temperature is read as -550 to 1250, the last digit is actually the digit behind the comma,'
'example 1: temp_c = -15 is actually -1,5°C'
'example 2: temp_c = 250 is actually 25,0°C.'
'Communication with the DS1621 is via the I2C bus.'
'Feel free to use and share this software!'
'DS1621 -->> DALLAS SEMICONDUCTOR Digital Thermometer and Thermostat'
'----------------------------------------------------------------------------------------------------'
'********************************* PORTS *********************************'
Config Sda = P1.0
Config Scl = P1.1
'*************************************************************************'
'******************************* VARIABLES *******************************'
Dim I2c_byte As Byte
Dim Loops1 As Byte
Dim Temp1 As Integer
Dim Temp2 As Integer
Dim Temp_c As Integer
'*************************************************************************'
'******************************* CONSTANTS *******************************'
Const Ds1621_i2c_address = &H0
Const Ds1621_i2c_r_address = &H1
'*************************************************************************'
'********************************* SETUP *********************************'
Config I2cdelay = 800
'*************************************************************************'
'******************************** PROGRAM ********************************'
Temp_c_loop:
Gosub Get_ds1621_temperature

Temp1 = Temp_c / 10                                           'calculate hundreds tens ones from temp_c'
Temp1 = Abs(temp1)

Temp2 = Temp_c / 10                                           'calculate 1/10th from temp_c'
Temp2 = Temp2 * 10
Temp2 = Temp_c - Temp2
Temp2 = Abs(temp2)

Print "T = ";                                                 'display T = '
If Temp_c < 0 Then Print "-";                                 'display "-" if temp_c < 0'
Print Temp1 ; "," ; Temp2 ; "°C"                              'display temperature as xxx,x°C'

Goto Temp_c_loop
'*************************************************************************'
'****************************** SUBROUTINES ******************************'
Get_ds1621_temperature:

For Loops1 = 1 To 2
Ds1621_start_convert:
I2cstart
I2cwbyte Ds1621_i2c_address
I2cwbyte &HEE
I2cstop

Ds1621_check_conversion_done:
I2cstart
I2cwbyte Ds1621_i2c_address
I2cwbyte &HAC
I2cstop
I2cstart
I2cwbyte Ds1621_i2c_r_address
I2crbyte I2c_byte , Nack
I2cstop
Temp1 = I2c_byte And 1
Temp2 = I2c_byte And 128
If Temp1 = 1 Then If Temp2 = 128 Then Goto Ds1621_check_conversion_done

Ds1621_read_temp:
I2cstart
I2cwbyte Ds1621_i2c_address
I2cwbyte &HAA
I2cstop
I2cstart
I2cwbyte Ds1621_i2c_r_address

I2crbyte I2c_byte , Ack
If I2c_byte > 127 Then Temp_c = &HFF00 + I2c_byte Else Temp_c = I2c_byte
Temp_c = Temp_c * 10

I2crbyte I2c_byte , Nack
Temp1 = I2c_byte And 128
If Temp1 = 128 Then Temp_c = Temp_c + 5

I2cstop
Next
Return
'*************************************************************************'
'********************************* DATA **********************************'

'*************************************************************************'