The industrial pt-100 temperature controller is designed using atmel 89c51 family of microcontroller . Analog to digital conversion: PT-100 temperature sensor is connected to con1 .Received signal is conditioned to TTL level before it is given to adc by the ic6 lm358. VR1 is a variable resistance used for calibration circuit
circuit The lm358 consist of two independent, high gain, internally frequency compensated which were designed specifically to operate from a single power supply over a wide range of voltages. The low power supply drain is independent of the magnitude of the power supply voltage. Application areas include transducer amplifiers, dc gain blocks and all the conventional op-amp circuits which now can be more easily implemented in single power supply systems.
For example, these circuits can be directly supplied with the standard + 5V which is used in logic systems and will easily provide the required interface electronics without requiring any additional power supply. We have following application notes given in the data sheet. For complete details refer to ic datasheet.
The ADC0804 family are CMOS 8-Bit, successiveapproximation A/D converters which use a modified potentiometric ladder and are designed to operate with any microcontroller or microprocessor These converters appear to the processor as memory locations or I/O ports, and hence no interfacing logic is required.
The differential analog voltage input has good common- mode-rejection and permits offsetting the analog zero-inputvoltage value. In addition, the voltage reference input can be adjusted to allow encoding any smaller analog voltage span to the full 8 bits of resolution.
Features :-
No Interfacing Logic Required .
• Conversion Time .. <100µs
• Easy Interface to Most Microprocessors
• Will Operate in a “Stand Alone” Mode
• Differential Analog Voltage Inputs
• Works with Bandgap Voltage References
• TTL Compatible Inputs and Outputs
• On-Chip Clock Generator
Capacitor C7 and resistor R15 are the part of on chip clock generation.
CS and RD are directly tied to ground so adc is always in read mode
WR and INTR are connected together and tied to p2.7 of the micro-controller.
Adc will output the data whenever low pulse is out from p2.7 pin and port 0 will read the 8 bit data from the adc data pins.
Features :-
No Interfacing Logic Required .
• Conversion Time .. <100µs
• Easy Interface to Most Microprocessors
• Will Operate in a “Stand Alone” Mode
• Differential Analog Voltage Inputs
• Works with Bandgap Voltage References
• TTL Compatible Inputs and Outputs
• On-Chip Clock Generator
Capacitor C7 and resistor R15 are the part of on chip clock generation.
CS and RD are directly tied to ground so adc is always in read mode
WR and INTR are connected together and tied to p2.7 of the micro-controller.
Adc will output the data whenever low pulse is out from p2.7 pin and port 0 will read the 8 bit data from the adc data pins.
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