OmniBoard KIT8: JPG decoder (063)

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last update: November 11, 2009.

 

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This is an intermediate dsPIC project.

It reads out an SD(HC) card to decode jpg files:

  • jpg image is shown on an RGB OLED.
  • Both SD and SDHC up to 4GB are supported.
  • FAT (FAT16) and FAT32 support.
  • Fast 40MIPS DSP decoding.
  • Image decode time 0.5 .. 3 sec for normal quality.
  • User menu control via RS232/joystick. See details below.

 

  • The four most common jpeg compression formats are supported:
  • Jpeg type 1: 4:4:4 No Subsampling YCbCr for best possible quality.
  • Type 2: 4:2:2 Vertically subsampled Y1Y2CbCr, the most common format.
  • Type 3: 4:2:2 Horizontally subsampled Y1Y2CbCr, (rotated type 2)
  • Type 4: 4;2;0 vert. and hor. subsampled Y1Y2Y3Y4CbCr for highest compression.

 

  • Assembled and programmed pcb.
  • Battery supply +3V5 ... +6V, integrated voltage regulator.
  • ON/OFF with single pushbutton.
  • Bootloader support.
  • Hardware is compatible with other omniboard projects and can be upgraded.
  • RGB 160x128 OLED and SD card to be bought separately

 

Shop:

 

  Free schematics, diagrams and downloads available.

KIT8 + OLED + SD, 4:4:4 No Subsampling YCbCr image decoded

 

  Downloads:  
   

 

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  Connections:  
   

How to make it work?

  1. Use a supply or battery between +3V5 ... +6V
  2. Optional terminal through RS232-1 @ 115200 bpS, 8N1, "type comm"
  3. MMC or SD(HC) cards must be formatted as FAT16 or FAT32.

 

RS232 terminal & bootloader.

 

 

In case you need to reprogram the dsPIC from scratch, then use the ICSP+ connector X3, connected to a hardware programmer, like the dsPIC USB programmer: WinPic800.

Omniboard ICSP+ (X3 connector) connection pins:

  1. !MCLR/VPP
  2. PGD (data)
  3. GND
  4. PGC (clock)
  5. +3v3
  6. leave open
  7. leave open
  8. leave open (closest to pcb corner)
 


 

Images: (click images to view full resolution)

   

pcb top view pcb bottom view

Diagrams: (click images to view full resolution)
   
  pcb top diagram pcb bottom diagram  

Component Datasheets:

Check out our development tools page.

Operation details:

  • Jpeg type 1: 4:4:4 No Subsampling YCbCr for best possible quality.
  • Type 2: 4:2:2 Vertically subsampled Y1Y2CbCr, the most common format.
  • Type 3: 4:2:2 Horizontally subsampled Y1Y2CbCr, (rotated type 2)
  • Type 4: 4;2;0 vert. and hor. subsampled Y1Y2Y3Y4CbCr for highest compression.

 

User Menu: joystick controls:

  • Right: open (sub)folder or file
  • Left: up one folder level
  • Up: select (scroll up) files and folders
  • Down: select (scroll down) files and folders
  • Enter: back to menu

 

User Menu: RS232 controls:

  • Not supported (yet)

 

 

 

 

terminal screen output (with all diags on, left click at boot)


 

 

 

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