the choice of microcontroller for specific purpose

[mdpai]

Hi,
I'm new to the embedded system world and i'm trying right now to get the grip of it.
1) My first question and maybe the simplest for you guys is how to choose a microcontroller knowing that I want to add:

2 USB Ports
2 Ethernet Ports (for router functionalities)
A Graphical LCD Screen
and a small keyboard/keypad.
Embedded linux

to the microcontroller board. What is the most important thing when choosing a microcontroller? is it the function we want to realize or the components we want to add around it.

2) Do the choice of components like USB ports or LCD Screen rely heavily on the choice of the microcontroller?

3) Can we connect directly the components to the microcontroller or do we need some kind of interface/controller between these 2? What are the main purposes of these controllers/interface exactly?

Thanks for all the answers and suggestions

 

[doraemon]

Hello!

One good way to choose a microcontroller is to find a page allowing to choose it
at the constructor site. For instance this one.
Now, what kind of graphics LCD do you want to use? Is it a very small
black & white device (e.g 96 x 64) or an UXVGA? This will very much influence
the choice.

What is the most important thing when choosing a microcontroller? is it the function we want to realize or the components we want to add around it.

The most important thing? I guess nobody can reply to that kind of question.
Of course, the functions are important and the I/O are also important.
What is more important for a meal? Eating or drinking? Both are important.
With no food you die, but with no water you also die.

2) Do the choice of components like USB ports or LCD Screen rely heavily on the choice of the microcontroller?

I don't understand this question. What do you want to know exactly?

3) Can we connect directly the components to the microcontroller or do we need some kind of interface/controller between these 2? What are the main purposes of these controllers/interface exactly?

It depends on the component and on the microcontroller.

If the component is a motor, then you most likely need an interface. if it's a LED,
then you may or may not need an interface, it depends on the LED and of the
current your ports can supply.

Dora.

 

[mdpai]

Thanks for the quick reply.

for the question 2, what I want to ask is wheather we need to first, choose the microcontroller and then choose the components based on that microcontroller. Or we can choose components eventhough we don't know yet which microcontroller we want to use.

I just want to use a small black and white graphical lcd.

In your opinion, for the components that I listed (USB, Ethernet, LCD, Keypad, embedded linux), Do I need for interfaces?

Thanks for the help.

 

[doraemon]

Hello!

I think I (more or less) got it.
You cannot choose the microcontroller first and then choose the peripherals.
Or did you mean choose the microcontroller family (i.e. the maker)?

Choosing the maker is quite a matter of taste. Ask 10 engineers, you will
get 10 advices and end up with 10 processor makers. Now if you know more
or less which one you want to use, then you can choose within one family.
As for the choice within a family, take the link I gave you above, and you
can setup many parameters (look at the hardware interfaces on the right,
e.g. ethernet, USB ….) Note that none of these processors has 2
ethernet interfaces, so I guess you will have to look somewhere else.

In your opinion, for the components that I listed (USB, Ethernet, LCD, Keypad, embedded linux), Do I need for interfaces?

Sorry, but I don't understand this sentence, there must be a typo somewhere
What do you mean by "Do I need for interfaces"?

Dora.

 

[mdpai]

Sorry for the typo..

I mean, for the listed components (USB, Ethernet, LCD, Keypad), do you think i need interfaces?

If for example I dont found any microcontroller that have 2 ethernet interface. Does it mean I have to buy a seperate interface for the ethernet?

Thanks for the answer.

 

[doraemon]

Hello!

As for ethernet, sorry, I cannot advice any dual port device. But you can take
a device without ethernet and put an outside device. There are some dual port
ethernet chips.

As for USB, there are devices.

Now for the keypad, it depends on the keypad. Do you have it already?
What kind of interface? line/clolumn contacts? SPI? other?

Same question: what kind of LCD (B&W, very low resolution or full color TFT)?
Will you use an external LCD driver (e.g. epson) or do you want to access
the LCD directly with the processor (in which case you need an LCD with an
internal controller chip)…

For instance on the first on does not have an internal memory and
therefore needs an external driver while the second one can be driven with
a low CPU power microcontroller.

Dora.

 

[mdpai]

Just one question before I answer all your question above.

If the microcontroller says that it has USB interface, does it mean that I can directly connect a USB port to the microcontroller? and if the microcontroller doesn't have any integrated interfaces at all, does it mean everytime i want to add a componant, i have to search for an interface for that componant?

thanks dora

 

[amahmud_89]

how can i design(software project) a 3 storied building elevator using microcontroller ? pls let me know in details ..for simulation i need to use proteus 7.2 ..

 

[Tahmid]

Hi amahmud_89,
You use a microcontroller, PIC or AVR or anything else. Sense input from switches to indicate which floor to go to. Use IR sensors to indicate which floor you are on and use retroreflective sensors for the doors.
All of this is required, and mainly you have to control a motor or something which moves the lift up and down.
Hope this helped.
Tahmid.
By the way, I'm from Bangladesh as well. Which university do you study in right now?