Datasheet

Jon Waddington
60
4.4 Temperature Measurement
The picture in figure 4.4 shows the temperature menu, displaying both inside and
outside temperatures in degrees Celsius.
4.4.1 Internal Temperature
To start the conversion of the temperature on the DS18B20 IC, the Propeller transmits a
reset pulse and awaits the response of the DS18B20’s presence pulse. The Skip ROM
command is transmitted (0xCC) followed by the Convert Temperature command (0x44).
The Skip ROM command saves time by skipping the transmission of the 64 bit ROM
code. The Convert Temperature command alerts the DS18B20 to begin the temperature
conversion. Figure 4.4.1.1 shows the waveform of the transmission of these two bytes
from the Propeller. Note that the least significant bit is transmitted first.
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
LSB MSB
LSB MSB
0xCC
0x44
Figure 4.4.1.1. Waveform of the Skip ROM and Convert Temperature commands
Figure 4.4. Picture of the Temperature Menu with the Internal and External Temperatures Displayed