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Altera_Forum's avatar
Altera_Forum
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8 years ago

Help with cyclone iv (ep4ce6e22c8n)

i need to connect a lcd hd44780 to fpga cyclone iv (ep4ce6e22c8n).

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So, i'm new in this thing and i really need to know how to phisically connect it; right now i'm using the LCD i said before but i don't know how to do it, please help.

I need it asap :cry:

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    There is a good basic overview here of HD44780 based LCD displays: https://en.wikipedia.org/wiki/hitachi_hd44780_lcd_controller

    As far as the physical connection goes, you need (3) 3.3V LVCMOS outputs, and (4) or (8) 3.3V LVCMOS bidir data lines.

    Cyclone IV does not support direct connection to 5V I/O, so if your display will need to operate at 3.3V LVCMOS levels, or you need to add a voltage level translator between the FPGA and the display pins.
  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    Oh thanks, but i'm still i bit confused about it. So i have to use the following pins: VSS, VDD, RW, E, and what else should i use? Am i even correct?

  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    --- Quote Start ---

    Oh thanks, but i'm still i bit confused about it. So i have to use the following pins: VSS, VDD, RW, E, and what else should i use? Am i even correct?

    --- Quote End ---

    Yes, for those listed.

    VSS would be connected to ground.

    VDD would be connected to (probably) +5V (or maybe +3.3V). Depends on your LCD module. You need a datasheet for it.

    RS is an input; needs to connect to an FPGA output.

    R/W is an input; needs to connect to an FPGA output.

    E is an input; needs to connect to an FPGA output.

    DB[0:3] are bidirectional; needs to connect to FPGA bidir.

    DB[4:7] (optional) are bidirectional; needs to connect to FPGA bidir.

    VO is an analog input / LCD contrast. Connect to the wiper pin on a 10K variable resistance. Other two pins to VDD and VSS.

    Attached is a PDF datasheet of a pretty standard 8x2 character LCD display from CrystalFontz for reference.