What's the function of a microcontroller that is put between a voltage source and a sensor (a low-power device)?

Thread Starter

letoppina

Joined Dec 11, 2017
27
Hello,

I have a very general question concerning digital electronics:

Given a sinusoidal voltage source (followed by its rectification circuit so that in the end the voltage is constant) and a final sensor (to be powered directly with the voltage source), why do I need to put a microcontroller between the two systems (between the voltage source and the sensor)? I guess the microcontroller drives the sensor with specific requirements (voltage/current)? How does it do that more specifically? I hope I made the question clear...
 

ericgibbs

Joined Jan 29, 2010
10,809
hi,
If I understand your query.
The power supply powers the sensor.
The sensor will have a digital or analog signal output.

This output is conditioning and processed by the MCU.
E
 

Thread Starter

letoppina

Joined Dec 11, 2017
27
hi,
If I understand your query.
The power supply powers the sensor.
The sensor will have a digital or analog signal output.

This output is conditioning and processed by the MCU.
E
I'm sorry, by output you mean input? The connection is made in the following way:
VOLTAGE SOURCE - MCU - SENSOR

So the MCU converts the signal from analog to digital from the voltage source before sending it to the final sensor?
 

LesJones

Joined Jan 8, 2017
2,698
I can think of no situation where you would have a microcontroller between a voltage source and a sensor. What is the purpose of this configuration ? Is the sensor sensing the voltage from the power source or powering the sensor ?

Les.
 

jpanhalt

Joined Jan 18, 2008
10,234
Actually the connections are made as in the sketch in attachment
That block diagram is very common. Very often the sensor will also have its own supply pins; however, some can be powered by the MCU or derive power from the communication lines (i.e., "parasitic power").

Still not clear on your question.
 

AlbertHall

Joined Jun 4, 2014
10,397
Some sensors only need power connected and they will produce an output depending on whatever they are sensing.
Some sensors will do nothing, even with power connected, until they are accessed by a controller - e.g. one-wire sensors, I2C or SPI based sensors.
 

atferrari

Joined Jan 6, 2004
4,093
Such a general question cannot get very specific answers.

Tell you a secret: if you manage to identify the sensor you have in mind, things would be easier for you and for those answering the question. The sensor is the key.
 

trebla

Joined Jun 29, 2019
209
The way of thinking that MCU is between power supply and sensor does not make any sense. The MCU is there for reading values from sensor (if it appears to sensor) and converting the readed values to another suitable data format. Power supply is for powering the MCU and probably another circuitry too.
 

OBW0549

Joined Mar 2, 2015
3,551
The way of thinking that MCU is between power supply and sensor does not make any sense.
Neither does the diagram presented in post #6. In fact, it makes me wonder if the TS knows what a sensor is and what it does.

The MCU is there for reading values from sensor (if it appears to sensor) and converting the readed values to another suitable data format.
Also possibly for configuring the sensor with digital commands, if it can be configured for such things as measurement range, scale factor, frequency response, filtering, and so forth.

Power supply is for powering the MCU and probably another circuitry too.
And for powering the sensor; the diagram in post #4 makes sense, whereas the TS's diagram does not.
 

Chris65536

Joined Nov 11, 2019
225
Actually the connections are made as in the sketch
The arrow is pointed the wrong way to the sensor. The sensor sends information to the MCU. The Power Supply block doesn't really even belong, since it's assumed that everything will get power somehow, and this is a block diagram, not a circuit schematic.
 
I am with Agustin;
The TS must provide details on the microcontroller and sensor.
Otherwise, we are running in circles like headless chickens.

Some sensors can be parasitically powered, like the 1- wire ones.
The ubiquitous DS18B20 temperature sensor being one example
 

panic mode

Joined Oct 10, 2011
1,856
and some types of sensors may need excitation or drive... for example inductive sensor, ultrasound, strain gauge etc.
while some sensors may not need active drive, adding drive may improve performance or robustness or improved error or crosstalk rejection, linearization etc. an example is modulation used in optical sensors etc. in such cases micro controller would be used as part of the sensor. industrial sensors make use of this a lot. the question is way too vague,
 
Last edited:

atferrari

Joined Jan 6, 2004
4,093
I am with Agustin;
The TS must provide details on the microcontroller and sensor.
Otherwise, we are running in circles like headless chickens.

Some sensors can be parasitically powered, like the 1- wire ones.
The ubiquitous DS18B20 temperature sensor being one example
The first that came to my mind was exactly the very first I ever used (LM135) in my very first project with a micro (16C57). That one you could use with a micro, obviously, but if needed, in a pinch, with a DMM. And it was my last up to now in a PID temperature controller.
 
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