About GND Pins

[NELMAN]

GND Pin in PWN Area
GND Pin in DIGITAL Area
GND Pin in POWER Area

I just want to know if they are same or what?


Cuz I want to use GND Pin in PWN Area to do Master/Slave Arduino, because the GND Pin in Digital Area and GND Pin in Power area are already used by CTE TFT/SD Card Shield.

[Grumpy_Mike]

Yes they are the same. They are not what.

[NELMAN]

Yes they are the same. They are not what.

So if I use that GND Pin in PWN Area, so the Slave Arduino must be connected to GND Pin in PWN Area?



GREEN = GND Pin

[DrAzzy]

All of the ground pins on a board are connected, they are equivalent and interchangeable. It doesn't matter which one you use.

[NELMAN]

All of the ground pins on a board are connected, they are equivalent and interchangeable. It doesn't matter which one you use.

Ah... nice ^_^

thanks dudes u find da wae :v

[aarg]

Arduino publishes schematics online. You can freely download and refer to them.

[promacjoe2]

True, all ground pins on the Arduino are electrically the same. But preferably when you are dealing with high current or inductive loads such as relays, you should use the ground pin closest to the power source. That is one of the two gnd pins next to the Vin pin.

[aarg]

True, all ground pins on the Arduino are electrically the same. But preferably when you are dealing with high current or inductive loads such as relays, you should use the ground pin closest to the power source. That is one of the two gnd pins next to the Vin pin.

Inductive or high current loads shouldn't be using grounds on the Arduino board at all. They should be connected directly to the power supply, with a star ground topology to return only signal grounds to the Arduino board.

[promacjoe2]

Inductive or high current loads shouldn't be using grounds on the Arduino board at all. They should be connected directly to the power supply, with a star ground topology to return only signal grounds to the Arduino board.

Do you mean like this Relay inductive load,

https://store.arduino.cc/usa/arduino-4-relays-shield

This is a new version, the old version had a much larger relay.

The point is that large loads or inductive load Gnd should not be put just anywhere. They should be placed as close to the power source as possible. This may mean using a separate power connector to the power supply or a separate power supply entirely. But when using a separate power supply, you may need to connect the Gnd together. And they should be connected on one of the two Gnd pins next to the VIN pin.

[aarg]

Your link is broken.

There is nothing on the Mega that can drive a large and/or inductive load. So it matters very little which ground you use, because the logic level interfaces to relay drivers and other drivers don't draw much current. The best place to join all the grounds would not be on any Mega pin. It would be a common point shared between the Mega ground and the load circuit ground.

[promacjoe2]

The link is fixed. It is to the 4 relay Arduino shield, From the creators of Arduino. So much for your claim that Arduino will not drive an inductive load. I would call for magnetic relays and inductive load. And because it's an inductive load, power and ground should be connected as close to the source as possible. It's good engineering practice to do so. Regardless of whether it would cause any problems are not. It's like a ground loop, you should avoid them whenever possible. You may only get one out of 1 million units that oscillate, but that one can cause a lot of problems.

We should refer to best practices. Not teach them how to do it one way, and when it causes a problem tell them they shouldn't have done it that way.

[Grumpy_Mike]

So much for your claim that Arduino will not drive an inductive load. I would call for magnetic relays and inductive load.

Yes but I would call driving the relay through a FET not driving it from an Arduino. So much for your so much.

We should refer to best practices. Not teach them how to do it one way, and when it causes a problem tell them they shouldn't have done it that way.

I disagree, you should teach a beginner the simplest solution for their current problem. To try and enforce best practice when the situation dosn't warrant it only serves to confuse and lessen the effect of that advice because they will soon find that in their situation it makes no difference.

We have a hard enough time getting beginners to fit decoupling capacitors that are always needed without getting them to jump through hoops when there is no need.

[promacjoe2]

The power for that FET has to come from someplace, Along with its ground. Unless that board has a separate power supply input, your FETs drawing power from the Arduino.


You have a hard time teaching because you're having to reteach over and over again. You're creating bad habits. And bad habits are hard to break. You cause problems by not instilling good habits from the start. I've worked as an automotive mechanic/AC/electronics technician for over 40 years. I have seen my share of people who have been taught bad habits. And is very hard to teach them how to break that bad habit. I find it much easier to teach someone how to do something if they never done it before, or have never had any instruction from anyone else. Whether it is how to use a torque wrench, using a lathe or milling machine, or diagnosing electrical problems. It all comes down to the same thing. Teaching the right way of doing it the first time and you don't have to reteach, Over and over again. And teaching safety is a big part of that.

Teach good habits, and you do not have to reteach the same thing over and over again.

[polymorph]

Current through Vcc also flows through ground.

[Grumpy_Mike]

Teach good habits, and you do not have to reteach the same thing over and over again.

Over teach and you put off people who begin to think it is all far too much to take on board. That is the problem with a lot of formal education in electronics, and it is considered an old fashion approach.

You have a hard time teaching because you're having to reteach over and over again.

No you have an easy time because you only try and teach what the student needs to know. Ever tried to teach physics? That is indeed what you have to do, classical, quantum, atomic, standard model and so on. The same topics in increasingly more detail introducing new concepts as they are needed.

I find it much easier to teach someone how to do something if they never done it before, or have never had any instruction from anyone else.

.
Indeed, but that is the difference between training and education.