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The module uses an inexpensive 8 bit Temperature Sensor the TMP37 from Analog Devices.Since the data was analog and the PIC16f84 does not have an analog input,an external ADC had to be used.Texas Instruments’ TLC549 was chosen for this.The advantage of this ADC was that it could communicate with the microcontroller serially.You may also use similar ADCs from Maxim-IC.The LCD is a normal 16×2 display which uses the Hitachi Controller HD44780.[more]
This project devised by two Cornell students in 2003,they wrote: For this endeavour, we first built an input stage that will amplify the input signal, as well as bias it to 2.5V (since the ADC can only sample positive signals). The ADC (MAX1111) is controlled by the microprocessor (Mega 32) using the SPI interface which was much easier than manually configuring a port to interface with the ADC(believe me, we tried that). We set the Mega 32 to sample the input at about 12 KHz which is fast enough to meet the Nyquist requirement for analog to digital sampling. The digital effects were done using by manipulating the input (which will be discussed in the Design page) and the output is passed to a R-2R DAC to a output amplifier stage and finally, to the speaker.[more]
This project use MAXIM MAX158 ADC CHIPย� to measure physical parameters like temperature, pressure and sound require an analog-to-digital converter (ADC). Furthermore applications like PC-driven voltage-based motor speed control and PC-based wave generators demand a digital-to-analog converter (DAC). Commerical ADC/DAC cards can cost hundreds of dollars.[more]
