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we are using temperature sensor PT100.I want to make temperature control system which range is -44 to 99 degree celcius.we want to use temperature controller that is used for two way for range -44 to 99 degree celcius and +4 to 99 degree celcius.when we used this controller range -44 to 99 then it operation when we switch ON power supply then it will show temperature as room temperature after 3min compressor start ON and to maitain temperature up to -44 when temperature goes beyond this range(upto adjustable 6 degree)then alarm ON display on LCD.when we obtain temperature -44 degree celcius compressor automatically ON/OFF as per temperature.same condition is for 4 degree celcius controller.I this Controller accuracy is main important it display temperature in floating values(eg.assume when temperature is -20 degree celcius it will show on display -20.1 whatever).Please help me on that
What are you going to program the 89c51 with... C or asm?
If you read this document, it will help with the design of the system https://www.electro-tech-online.com/custompdfs/2012/07/2005JUN07_STECH_ANPDF.pdf You need to linearise the PTC output before you read it on a micro... You will need to select a decent ADC, I don't know how you intend to compensate for temperature. The best way is use the four wire system in the document and keep the rest of the circuit at room temperature...
Have you started a program yet? You will need an LCD routine, possibly an I2C / SPI routine ( for the ADC ). If you are using C, the math will be easy enough.
Displaying a "mapped" input voltage on a LCD will be very easy ( even with two decimal places ).. Controlling the compressor is very easy as well ( a transistor controlled relay for the a/c ).
Have you designed the circuit yet? Once you have, we can run up a flow chart for the code....
I mainly program in 'C'... I do have certain routines done in 'asm', when speed is required...
You need a plan first... You need to know ADC information etc... Choose your components first. you need to see how to interact with them
LCD on port ?
ADC on port ?
Memory on port ?
Thermister...NTC on port ?
Then get the common items going.. ie.. get the LCD running (then it will be easier to debug.)
I find it easier to get a simple design up and running... then add the components one at a time...
I have gone through your circuit diagram. Here you have not mentioned that which make of PT100 you want to use,because there configuration with 2 wire and 3 wire available in the market with different. If you dont want use the heater and cooler than simply you can remove ULN which is bridge IC and the LCD which has the data lines connected the Port 0 so it need to be having the pull up resistor with it of 10k.
i want to use switches for to set temperature whatever i want to set between range -99 to 99 degree celcius.When i switch on whole system compressor will start after 3min it will ON up to setable temperature after temperature maintain compressor will OFF.In this system we can set temperature and time.If compressor will OFF at set temperature and temperature get varies at setable temperature at 6 degree increment or decrement buzzer and LED will indicated and Compressor ON if temperature decrement.
thank you sir for your guidence. Please sir i am new in assembly programming i want to help in assembly programming...........Please sir give me your valuable time
Sorry buddy I may not be able to help you out with assembly language programming, I am not good at assembly...
But is there any specific reason you want to use assembly you can use c also, and if you are using C then may be i can help you out with your programming....
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