外文翻譯---基于單片機的多功能溫度檢測系統(tǒng)的設(shè)計-單片機-在線瀏覽
2025-07-31 10:13本頁面
【正文】 ture measurement principle diagram shown in figure . Low temperature coefficient graph oscillation frequency vibration product temperature is used to produce with fixed frequency, pulse signal to counter l. High temperature coefficient crystals temperaturedependent its oscillation frequency change significantly. The signal generated as the counter 2 input pulses. Counter 1, 2 and temperature registers are counter in 55 degrees preset corresponding a base value. Counter l to low temperature coefficient of the pulse signal generated crystals, when the counter for subtraction counting the preset value reduced to 1, when the temperature counter O value will add l, counter the preset value will be l man again, to counter the l start low temperature coefficient of crystal oscillator pulse signal, so cycle count until the counter 2, stop counting to O accumulative temperature, temperature of the register for the register is measured values. Figure accumulative used for the slope pensation and fixed temperature measurement, the output of the process of nonlinear correction is less than the preset value counter l. ② .AT89S52 interface mode and DS18B20 Chip DS18B20 and the connection has two kinds: namely parasitic power and external power supply mode. Parasitic power way: in the parasitic power supply mode, the signal from the single chip DS18B20 in line drawing energy during the high level in the DQ energy stored in 6 the internal capacitance, low level in signal in the energy consumed during the capacitance on working until highlevel ing again to parasitic power (battery). Parasitic power mode has three advantages: 1) distance measuring temperature, without the local power supply. 2) no conventional power in the condition reads the ROM. 3) circuit, with only one more concise root I/O realize temperature measurement. Want to make precise temperature conversion chip DS18B20, I/O line must ensure that the temperature conversion period, due to provide enough energy conversion in temperature during each DS18B20, when the current 1mA to work a few temperature sensor in the same root hanging on the I/O multipoint temperature measurement, only by K and resistance will not be able to provide enough energy, which cannot be switchover temperature or errors. The external power source supply way: in the external power supply modes, DS18B20 work power by VDD pin, I/O access line does not need strong pull up, there is no shortage of electricity power, can ensure accuracy and conversion in the bus theory can be articulated multiple sensor DS18B20, multipoint temperature measu
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