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UART to USB and SPI to USB

Discussion in 'Datasheets, Manuals and Component Identification' started by anroop, Sep 23, 2014.

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  1. anroop


    Dec 11, 2013
    I am trying to connect a Barcode reader (Scan engine having UART o/p) to a Tablet PC through USB OTG (Android 4.4.2, Chinese vendor). I have chose to use PL2303HXD IC for this, I don't know if the Tablet PC would support the IC and accept it as Plug&play,if not please suggest me a IC that does so.

    To connect a OLED display (dd-25664be-3a , Densitron) (SPI 3-wire) to the same Tablet PC via USB OTG. Please suggest me a Good equivalent SPI to USB IC.

    Note: 1 & 2 will be connected to the tablet PC via a USB HUB through USB OTG.
  2. Gryd3


    Jun 25, 2014
    This may be heavily dependant on the tablet PC's software and hardware.
    What is the device model, does it support USB OTG?
    what is the device's OS?
    Will the usb hub be powered or passive?
  3. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    Not may, it definitely depends.
    The USB-to-xxx converter chips provide the physical interface from USB to e.g. RS232, PSI or whatever. They do not provide the conversion of the logical interface (protocolls).
    Take the barcode reader: It will deliver the scanned code probably as an ASCII sequence via its UART interface. The USB port on any machine cannt understand this. You need a driver which emulates a COM port (serial port) on the USB side of the connection and you need to interface to this virtual COM port via the software on the PC, tablet etc. The USB interface only transports the COM data and presents it to the barcode reader or reads it from the barcode reader via a physical RS232 interface.
    Note that apart from the USB bridge you will need an RS232 transmitter chip to interface the bridge chip to the RS232 voltage levels.

    You can buy such interfaces complete with bridge and level translator (search USB to serial converter). There is still the issue of the driver required for your OS.
  4. anroop


    Dec 11, 2013
    I have tried using a Ready-made barcode reader with USB interface, Mouse,Keyboard through Both Powered / Passive USB hub to Tablet PC (OS: Android KitKat, USB OTG) and its working great. The barcode reader that I have is just a raw engine that gives out UART (TTL) output in ascii format. Now I need to try adding a UART to USB converter IC (to add a circuit of my own) and connect it to same Tablet PC and test,to know if it works!. That's I needed suggestions from you guys.
  5. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    You've got our suggestions. What else do you require?
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