What is the difference between AD conversion and optical separation circuit?

AD conversion is to collect voltage signals, and optocoupler circuits are generally used as optoelectronic isolation

The question is whether the signal collected by your sensor is analog or frequency (generally called switch), and the analog quantity (voltage) must of course be converted into a digital signal signal signal (binary number, corresponding to your AD reference voltage VREF has a certain relationship, v = VREF 2 n bits-1 * binary number) and finally use AD conversion to be processed in the MCU.

If the switching quantity can be isolated by ordinary optocoupler to collect pulse counting, this can use the counter inside the single-chip microcomputer, of course, this signal needs to be sent from int0 or int1, and the corresponding trigger mode can be set with the internal counter.

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I still don't understand your intentions, AD conversion is to collect voltage signals, and optocoupler circuits are generally used as optoelectronic isolation, increasing anti-interference ability, etc., but there is nothing to do with it. The question is whether the signal you collect is analog or frequency, of course, the analog quantity must be converted into a voltage signal and finally converted by a d, and if you add optocoupler, it is also a linear optocoupler, and the role is also isolation, this kind of optocoupler is very expensive. If the frequency is used, it can be isolated by a normal optocoupler and the pulse count can be collected.

After talking for a long time, you still don't understand what kind of signal you want to collect. I guess you should be the latter frequency signal, but you think about the problem too complicated, using the amplification integration method, the actual acquisition is the change of pulse frequency.

Generally, the sensor is an analog signal, and if you use an amplification circuit, it must be an analog signal, and the analog signal must be converted by AD before it can be processed by the single-chip microcomputer. I don't know what kind of microcontroller you are using, with or without an AD converter.

Optocouplers are generally used for optical separation circuits, I have used TLP521, and I searched the PDF document on the Internet, and it is very easy to use. The optocoupler mainly plays the role of isolation to prevent the analog part of the circuit from interfering with the digital circuit of the subsequent stage.

The microcontroller receives digital signals, so the AD converts the analog signal into a digital signal, and the optical separation does not know.

The so-called AD conversion is the conversion of analog quantities into digital quantities. Because the basic mode of processing information of our computers, CNC equipment, robots, etc., is Boolean logic, that is, based on and or without circuits. At this time, it is necessary to convert some analog information from the outside world into digital information for data processing.

For example, the AD module of the PLC, the serial pulse encoder of the servo motor and so on have this function. Remember the answer sheets when we were students? Our admission ticket number or ID number, and even the ABCD of multiple-choice questions, etc., are more or less a bit of a D conversion.

It is an analog-to-digital conversion circuit that converts an analog signal into a digital signal.

Analog and digital signal conversion circuits.

Op amps are generally used to amplify signals. You can divide the voltage with a resistor, but depending on your accuracy, choose a precision resistor. Otherwise, the temperature drift is too large.

You can go to major companies to see, the general electronic market is also in books, the kind of 8-bit simple AD, there are special needs should be ordered.

This is an AD company, and I personally feel that AD's chip is easier to use.

51 MCU inside no AD need to add AD chip, AD with 8 teaching feet AD0832 this two channel input, you find an AD0832 manual on it, you have a reference design circuit, there are a lot of AD0832 programs on the Internet, I believe you can complete the design, if you really can't figure it out, I am helping you find the circuit merger program.

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If only the presence or absence of light is detected, an op amp and AD conversion circuit are not required, and a voltage comparator is sufficient. Because you need to.

After a d conversion, the output digital signal can be 8 bits, 10 bits, 12 bits, 14 bits, and 16 bits.

How a D converter works.

Successive approximations.

Successive approximation A D is a relatively common A D conversion circuit, and the conversion time is in the microsecond range.

Double integral method. A D converter using the double integration method consists of electronic switches, integrators, comparators, and control logic.

Voltage-frequency conversion method.

A D converter using the voltage-frequency conversion method, consisting of a counter, a control gate, and a clock gate control signal with a constant time, such as:

It works on the principle that the Vf conversion circuit converts the input analog voltage into a pulse signal proportional to the analog voltage. Voltage-frequency conversion method.

It can be simply traced with a formula.

The data in the formula is defined as follows, vs represents the reference voltage, vin represents the input voltage (the maximum vin is the value of the reference voltage), and you use a 10-bit AD, so the final output data can be expressed like this:

out=(vin/vs)*(2^10-1);where the index 2 10 is 1024;

For example, when the input voltage is 4V, he will output 1023, when the input voltage is 0V, it will output 0, and when the input voltage is 1V, the output will be.

256 (calculated value is, this introduces the quantization error caused by AD conversion, and is also the ultimate culprit that leads to the limitation of AD accuracy).

The general working process of converter conversionParallel comparison type A D converter successive comparison type A D converter double integral type A D converter The main technical indicators of the converter integration A D converter and its application converter overview function: the analog voltage can be converted into the corresponding digital quantity proportionally. Input, Analog, Voltage, Output, Digital, ADCDN Converter Classification: Parallel Comparison Features:

The conversion speed is fast, the conversion time is 10ns 1s, but the circuit is complicated. Successive approximation features: moderate conversion speed, conversion time of several s 100s, high conversion accuracy, and a good balance between conversion speed and hardware complexity.

Characteristics of double integration type: the conversion speed is slow, the conversion time is hundreds of seconds and a few ms, but the anti-interference ability is the strongest. The general working process of conversion is continuous analog signal sampling and holding, quantization time discrete signal value is also discrete signal value and discrete signal value are discrete in time and value of digital signal encoding A D converter generally includes sampling, holding, quantization and coding 4 processes.

tg1.Sampling vs. holding sampling is the conversion of a continuous analog over time to a discrete analog over time. (t)ii(t)o(t)s(t)s(t)=1:

Switch off s(t) = 0: the higher the frequency of the switch off the sampled signal s(t), the more the acquired signal can reproduce the input signal after passing through the low-pass filter. A reasonable sampling frequency is determined by the sampling theorem.

0s(t)t sampling theorem: if the frequency of the sampled signal s(t) is fs, and the frequency of the highest frequency component of the input analog signal i(t) is fimax, then fs 2fimaxo(t)0tst0t sampling and holding circuit and working principle are converted by analog signal.