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18F2550 USB Connections

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  • 18F2550 USB Connections

    This PIC lists USB in features.

    Does this mean all you need is a hardware connection to USB connector on a breadboard or PCB?

    Companion question.

    Are the MELoader bootfiles available somewhere?

    I think that would be a little more direct than using Microcode loader.

    Saw PIC dev board with MELOADER sticker on it in Chuck Hellebuyck book.

  • #2
    As for USB, I spent 9 months reading the PBP USB related material, MicroChip's related Application Notes & Technical Bulletins, as well as Jan Axelson's USB Book. I breadboarded numerous attempts with numerous versions of software. I came to the conclusion the only way to implement USB was to spend the $400 and purchase HIDMaker software. I did, and I am finally communicating with USB. Be forewarned, even when you can get a PIC to talk to a PC via USB, you still need to create a PC side program to interpolate & display your processor's data, as well as transmit PC-to-PIC programming data. I am using Visual Studio 2015; specifically Visual Basic (Part of the Visual Studio Suite). USB isn't a simple Special Function, it is a giant project all by itself. If you are determined to use USB, save yourself a bunch of trouble; buy HIDMaker software, buy Jan Axelson's USB Complete book, buy Visual Studio 2015, and buy Murach's Visual Basic 2015. I happen to be Hell bent on using USB, and this is the path I traveled. I spent time & money on additional materials that weren't worth mentioning as well. You may be able to get there cheaper than I did, but I share my story.
    We can crack this cotton PIC'n thang!


    • #3

      CCS seems to think loading their program to an 18F14K50 and a hardware connection will work.

      That is about my limit with USB.

      Compiling in IDE and programming with PICKit is fine with me.
      Last edited by PICBasicUser; 10-02-2017, 07:56 PM.


      • #4


        Did you look at Serial. I2C and USART?


        • #5
          Yes. I create electronic controls as part of my day job. Since laptop computers haven't had DB9 Serial communication ports in several years, designing a product to talk with a laptop requires modern USB. Component to component communications, USART is preferred, but some components (like digital pots) use SPI and I2C (and sometimes communications protocols of their own design).

          If I want to have a PIC18F26K22 talk to a PIC16F1824, I can select from the ready-made comm options. Furthermore, I can create my own protocol; how long is a packet? What is in the first byte? And so forth. With USB, EVERYTHING is predefine except for the actual data being transferred. Get one thing wrong and it just doesn't work. There's no error code to tell you what you did wrong, it just won't enumerate, or communicate if you do have the handshake part right.

          I'm not trying to discourage you. I just don't want you to get discouraged. If you know going in that USB is going to take some serious effort, hopefully you won't get frustrated when it doesn't work the 3rd time. If you have good reason to need USB, then at least buy Jan Axelson's "Complete USB, Fifth Edition" so you have something to refer to while you learn.
          We can crack this cotton PIC'n thang!


          • #6


            Like in my PIC book 'We will deal with that later' and 'Let's keep it simple now'.

            I will code and compile in PIC Basic.

            Then program with MPLAB IPE and PICKit3.

            No bootloader. No USB connection for now.