USB Computer Status DisplayNovember 6, 2012

This project is a USB based computer status display.  It connects via USB and is driven by a PIC microcontroller. It listens for a small set of commands, using those to implement a simple control protocol to drive the screen.

Parts List:
  1. 1x NHD-0440WH-ATFH-JT [P1] -Display itself. Exact model isn’t critical. It is a 4×40 character driven by 2x SPLC780D ICs.
  2. 1x 20KΩ potentiometer [R3] – adjusts display contrast
  3. 1x NPN FET [Q1] – Exact model isn’t critical. I had some MPSA42_D26Z FETs laying around.
  4. 1x 1KΩ resistor [R5] – FET gate resistor. (Shouldn’t be needed)
  5. 1x 22Ω resistor [R6] – Backlight current limiting resistor.
  • Micro-controller and supporting hardware:
  1. 1x PIC18F2550 [U2] – PIC18F micro with USB support
  2. 1x 10KΩ resistor [R4] – Used for MCLR pullup
  3. 1x SPST switch [S1] – Reset switch. I used a SKRGARD010.
  4. 2x 18pF caps [C1] [C2] – Caps matched to the 20MHz crystal
  5. 1x 220nF cap [C3] – Filter cap used by the micro-controllers’ internal 3.3V regulator used for USB support
  6. 1x 6 Pin Header [P2] – ICSP used to program micro-controller
  7. 1x USB cable [P3] – Powers project and allows communication

Via: DFRobot, Source: Andrew Gehringer

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