the choice of microcontroller for specific purpose

Discussion in 'Embedded Systems and Microcontrollers' started by mdpai, Jan 11, 2010.

  1. mdpai

    Thread Starter New Member

    Jan 5, 2010
    8
    0
    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
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    I suspect that all those communication capabilities, plus embedded Linux, puts you into the SBC (single board computer) area. Googling "sbc + linux" gets hit like this one - http://www.appliedlinux.net/
     
  3. mdpai

    Thread Starter New Member

    Jan 5, 2010
    8
    0
    I take a look at single board computers and it's out of my spec. I don't need fast processors. Below 100Mhz is fine..

    Thanks for the suggestion
     
  4. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    Sounds like you need to check out Microchips Pic32MX with USB on the go ( USB OTG). Besides the embedded Linux, it can do everything else....... but then again, I have not seen embedded Linux ported to any Microcontroller...

    My .02
     
  5. mdpai

    Thread Starter New Member

    Jan 5, 2010
    8
    0
    Thanks, I've read uclinux.org and it says I can embed linux to a microcontroller.

    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?
    For example if microcontroller A have one USB interface, and in fact I want to add 2 USB port. Does it mean I can connect one USB directly to the microcontroller, and for the other USB port, I have to search for an interface?

    Thanks
     
  6. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    Yes you would have to have another device to control another USB port, the PIC32 can be either a USB host or a USB HID device, so if you need more USB ports I would look into the FT232BM series of USB to serial converters >> http://www.ftdichip.com/Products/FT232BM.htm, these are by far the easiest to implement in any microcontroller project requiring USB functionality.

    As for the Ethernet Microchip has a standalone Ethernet Controller IC >> http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en022889, this will enable you to implement a variety of stacks provided by microchip for TCP/IP, DHCP, SNMP, BSD Sockets, etc.... You would only need one ethernet port on the microcontroller side, if you need to communicate to multiple devices on the network, just add an ethernet switch/hub....
     
  7. maxpower097

    Well-Known Member

    Feb 20, 2009
    795
    388
    Actually the PIC32 can operate in 3 modes. Host, device and OnTheGo. The OTG will allow you to switch back and forth between a host and device through software changes alone. So when you pluged it into a PC it would hook up as a device, then you could turn around and plug in a jump drive and it would act as a host.
     
  8. Tahmid

    Active Member

    Jul 2, 2008
    344
    25
    Hi,
    I think for Linux, you need a powerful processor with atleast 200MHz processing speed.
     
  9. maxpower097

    Well-Known Member

    Feb 20, 2009
    795
    388
    I know they started work trying to get it to run on the pic32 but not sure if any progress has been made. I think last I checked they had it load half way.

    Found this post on MC's forum

    "If you are wanting to run Linux on the PIC32 then it is not ready for it as there is not enough onboard Flash and RAM (Linux really needs >2MB as a bare minimum)
    Once Microchip adds external memory bus access then it will be possible... especially if they include a MMU, then you could run generic Linux.

    There are a number of RTOS that work on the PIC32.. one is even POSIX based and is very Linux Like... see list at
    http://www.pic32.org/rtos.php "
     
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