Pc Data Loger

8/7/2019 Pc Data Loger

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1.Introduction.

2.Component list.

3.Working Principal.

4.Circuit diagram.5.Conclusion.


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Semiconductors:1 programmed 8051 or even any EPROM down to the old 2716

1 8*128k static RAM

1 MAX232 or ADM232

1 MAX690 or ADM690

1 SAB-C515

1 74HC 141 74HC 573

2 1N 4151

1 78O9 regulator

1 7815

1 ICL7660

1 TL064 Capacitor:

2 33pF cer

14 100nF cer

6 10F

1 100F

1 1F Resistors:

1 27


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1 100

8 1k10 27k

1 100k

10 470k Mechanic:

1 12MHz crystal

1 Sub-D socket, 9 pin

1 cable, Sub-D plug-plug, 9 pin

1 pbc

1 some thin wire

1 low voltage power connector


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Data acquisition is the process by which events in the real world are sampled and

translated into machine-readable signals. Data acquisition typically involves

sensors, transmitters and other instruments to collect signals, waveforms etc. to be

processed and analyzed with a computer.The components of data acquisition systems include appropriate sensors that

convert any measurement parameter to an electrical signal, which is acquired by

data acquisition hardware. Acquired data typically is displayed, analyzed, and

stored on a PC. In our project the Temperature data was monitored by using the

Microcontroller & PC. The Project has an Inbuilt Data logger which is used to Log

the Temperature data on the PC.

A data logger is any device that can be used to store data. This includes many data

acquisition devices such as plug-in boards or serial communication systems which

use a computer as a real time data recording system. The Microcontroller AT89S52

has 8K Bytes of In-System Programmable (ISP) Flash Memory.


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Signal Inputs

Each input has a protection resistor, a resistor to ground and an

amplifier. The protection resistor ensures that overvoltages do not

destroy the input of the amplifier. In case that to all channels an

overvoltage is applied, voltages up to approximately 50 volts are

allowed. The pull down resistor guaranties always a defined input. Theamplifiers reduces the impedance for the inputs of the MCU. Their

output resistor prevents high currents flowing into the MCU when the

amplifier drive their output above 5 volts or below ground.

Power Supply

The power supply generates three different voltages: +/- 8 volts and 5

volts. If rail-to-rail OP were used, the generation of 5 volts only wouldhave been sufficent. Also the output resistors of the amplifiers could

then be omitted. Single-supply OP can be used with 8 volts and 5 volts

for the digital parts.


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MCU Circuit

The SAB-C515 comes along with 3 timers, a boud rate generator, a 8

channel 8 bit ADC with range selection and many features more. But it lacksany program memory. Therefore an EPROM is added to the circuit. With the

same bus as for the EPROM a 128K bytes SRAM is connected to the MCU.

It can be accessed in two banks, because the linear address space of 8051

is limited to 64K bytes. One bank stores the measured data. The other bank

saves only the configuration and is therefore mainly empty. If no power is

applied to the circuit, the MAX690 takes care of the SRAMs power supplyand by this way also of the stored data. The circuit is no low power design. I

measured a consumption of 60mA.

Software

The MCU software as many jobs to do: Process commands from the RS232

interface, take care of of the measurement sequence and timing, check

counters for overflow, update the display and respond to the button. The

main program looks for flags set from the interrupt subprograms, new data

on the serial port and the button. If the measurement flag is set, the

measurement sub program will be called.


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If a command is via RS232 received, all measurements are stopped and the

command is processed. After this operation is compleatly finished the MCU

returns to the main program and waits for further instructions.Timer 0 and 1 are used for the measurement of pulses on the digital inputs. The

timers are expanded by interrupt driven routines that register every overflow.

Otherwise it could not be distinguished between 65536 and one pulse. Timer 2 is

used to generate a clock rate of 10 Hz. This clock is feed via an interrupt into a 16

bit software counter. The software counter counts down and activates when ever

it reaches zero the measurement subprogram and reloads the through theconfiguration given number.

The measurement subprogram reads the configuration data and execute the

required measurement. First the voltage of all analog input channels is

determined. Then timer 0 is stopped, read, reset and restarted. For timer 1 the

same procedure follows.


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A data logger is any device that can be used to store data. This includes many

data acquisition devices such as plug-in boards or serial communication

systems which use a computer as a real time data recording system. The

Microcontroller AT89S52 has 8K Bytes of In-System Programmable (ISP)

Flash Memory.

Pc Data Loger

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