pic microcontroller based temperature monitoring and control

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scientistumair
Posts: 4
Joined: 08 Jan 2010 10:52

pic microcontroller based temperature monitoring and control

#1 Post by scientistumair » 08 Jan 2010 11:08

I am new in microcontroller. I have task to design pic microcontroller based temperature monitoring and control using pt100 as sensor. Total 8 pt100 are to interface with pic16f877a. Set points are to be given by keypad and display should be on lcd. which control tecqnique(PI ,PID or pwm) should be used
First I am controlling and display 1 temperature(i.e. using 1 pt100)

I have following difficulties:
when I interface pt100 to pic then my pic doesnot read analog voltage voltage drop to constant -0.875volts at input of microcontroller. Circuit is as follows
1ma current source-voltage follower-noninverting amplifier-pic16f877a
I am using lm324 quad opam ic for current source and for amplifier.
Second how to develop variable pwm in pic using c compiler (difference b/w set point and process variable)
Third how to interface keypads? How to display both setpoint and process variable?
Fourth which control tecqnique(PI ,PID or pwm) should be used?

Graham1904
Posts: 2
Joined: 26 Jun 2010 09:08

Re: pic microcontroller based temperature monitoring and con

#2 Post by Graham1904 » 26 Jun 2010 09:12

I would personally suggest that, unless you want to measure temperature over a wide (even low) range, that you yse the Dallas DS18B20 as this transmits a digital temperature and thus does not need any PT100 amplifiers etc.

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tihomir.losic
mikroElektronika team
Posts: 2138
Joined: 02 Dec 2009 14:16
Location: Serbia
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Re: pic microcontroller based temperature monitoring and con

#3 Post by tihomir.losic » 28 Jun 2010 09:10

Hello,

first of all, I want to recommend you our newer release of mikroC PRO for PIC.
Its development environment includes a set of features such as easy-to-use IDE, very compact and efficient code,
hardware and software libraries, comprehensive documentation, software simulator, hardware debugger support,
COFF file generation and many more. Numerous ready-to-use examples will give you a good start for your embedded projects.

Secondly, DS1820 is the better solution than PT100 sensor.
DS1820 datasheet: http://pdfserv.maxim-ic.com/en/ds/DS18S20.pdf
The DS18S20 communicates over a 1-Wire bus that by definition requires only one data line (and ground) for
communication with a central microprocessor. In our compiler, this sensor is supported, and you can use
OneWire library.
Third how to interface keypads? How to display both setpoint and process variable?
The mikroC PRO for PIC provides a library for working with 4x4 keypad.
The library routines can also be used with 4x1, 4x2, or 4x3 keypad.
More about this library, on this link...

I hope that this will help you in your decision.
For any further assistance, feel free to contact us.

Best regards,

Losic Tihomir
mikroElektronika [Support team]

Graham1904
Posts: 2
Joined: 26 Jun 2010 09:08

Re: pic microcontroller based temperature monitoring and con

#4 Post by Graham1904 » 28 Jun 2010 09:26

I have afeeling that the DS18S20 is obsolete and that it has been replaced with the DS18B20

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