DS18B20 Programm

Hallo Leute,

ich habe vor, einen DS18B20 an einen Mega32 zu hängen. Lt. Datenblatt
kann der 0,5°C genau. Jetzt habe ich ein Programm gefunden, das 0,1°C
kann.

Kann mir einer das ein wenig erklären?
Dann gibt es noch eine Aussage in Datenblatt.

"The core functionality of the DS18B20 is its direct-to-digital
temperature sensor. The resolution of the
temperature sensor is user-configurable to 9, 10, 11, or 12 bits,
corresponding to increments of 0.5C,
0.25C, 0.125C, and 0.0625C, respectively. The default resolution at
power-up is 12-bit. The DS18B20
powers-up in a low-power idle state; to initiate a temperature
measurement and A-to-D conversion, the
master must issue a Convert T [44h] command. "
...
"The DS18B20 output temperature data is calibrated in degrees
centigrade; for Fahrenheit applications, a
lookup table or conversion routine must be used. The temperature data
is stored as a 16-bit sign-extended
two’s complement number in the temperature register (see Figure 2). The
sign bits (S) indicate if the
temperature is positive or negative: for positive numbers S = 0 and for
negative numbers S = 1. If the
DS18B20 is configured for 12-bit resolution, all bits in the
temperature register will contain valid data.
For 11-bit resolution, bit 0 is undefined. For 10-bit resolution, bits
1 and 0 are undefined, and for 9-bit
resolution bits 2, 1 and 0 are undefined. Table 2 gives examples of
digital output data and the
corresponding temperature reading for 12-bit resolution conversions.
"
Gruss

Dirk