Gast
#296886
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 twos 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