What microcontroller i should use in my oscilloscope project?

Discussion in 'Embedded Systems and Microcontrollers' started by adriang, Nov 17, 2012.

  1. adriang

    Thread Starter New Member

    Nov 17, 2012
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    Hi Everyone!

    I don't know what microcontroller i should use for my school project.I must build an oscilloscope then send the signal to the PC. The signal will be displayed into a java application created by me.
    I am entry level in this field, i have 3 months deadline to do this,many information about this project i don't have, my teacher say: create-display-analyze-use your imagination-read more books so i need help, any information or other suggestion is welcome.

    Thanks in advance and sorry for my bad english!
     
  2. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    It is going to depend how accurate and how fast you want it to be. There is a project in the Completed Projects collection. It uses a Pic 18F family, I believe. It might not be able to sample high frequencies but it is certainly cheap to build.
     
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Some kind of PIC with a USB interface, exactly which one would depend on how fast you need to go, ie, the sampling rate.

    Microchip has lots of sample programs that do the basic USB functions, you'd just have to graft your A2D parts onto something that is already doing most of the heavy lifting.

    And as you're being told to do research, I've seen complete sample scope projects using PICs, though they did not have a USB, they displayed the signal on a graphic display (which the PIC drove).
     
  4. takao21203

    Distinguished Member

    Apr 28, 2012
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    PIC32 can do 1 Mega samples/sec.
    And some PIC32 also have USB.

    It is possible just to use a blank chip, together with an ICSP device programmer.
    Or alternatively, also there are evalution kits and PCBs available, from Microchip, and from 3rd parties.

    18F is not so much suitable for a digital oscilloscope, only if you only need a low sample rate.
     
  5. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    I recently did 1 Msample/sec on a PIC 18F running at 64MHz (16MHz HSPLL).

    Although the ADC was officially "out of spec" the ADC readings were still within about 1-2% error per sample.

    USB enabled PICs are not needed, you can get high speed serial->USB converters on ebay for $3 each so you only really need a PIC with a serial port, which gives more PIC part options and makes coding easier.
     
  6. adriang

    Thread Starter New Member

    Nov 17, 2012
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    Hello,

    Thanks to all for the answer!After reading some books and saw some project I have 3 microcontroller who I can choice: atmega32,pic18f4550 and 80c51.I don't want high perfomance i just want to see my project works :). I think I will choose pic18f4550 it will be more interesting to use the USB function.But I'm not so sure about the conection Rs232 or USB?Thanks
     
  7. nigelwright7557

    Senior Member

    May 10, 2008
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  8. ErnieM

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    Apr 24, 2011
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    RS232 is easier as far as the software goes, just write the bytes to the transmit register, but needs the hardware for level shifting (1 IC) and a connector... plus your PC may not have a serial port so you need an RS232 <=> USB converter.

    USB is easier as far as the hardware goes, just a socket and maybe a resistor, but needs more work to get the software to work, which may just mimic an RS232 anyway.
     
  9. takao21203

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    Apr 28, 2012
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    Do you use USB?
     
  10. ErnieM

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    Apr 24, 2011
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    Frequently.
     
  11. takao21203

    Distinguished Member

    Apr 28, 2012
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    OK I mean if you use to program the interface. That can be done emulating RS232, but normally it is different.

    There is provision for in packet and out packet buffers, interrupts, and endpoints, just to name a few things. And usually the USB stack is provided kind of ready-to-use.

    Does such a thing exist for RS232? It comes from an age where normally a small sequence of assembler was used, inluding a few BIOS calls. So even if there are more modern interfaces, similar to a "stack", these are non-standard.

    I don't understand "easier to use". To program a fully bidirectional RS232 stack both on the chip and the host is a lot of work to do.

    My opinion is that USB is far better, and easier, once you are familiar with it. It is not even required to understand all options. It is fairly easy to make it working somehow, at least for Microchip controllers. There are many samples included.
     
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