PicoVGA01

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PicoVGA FRONT 3D.png

PicoVGA

PicoVGA uses a Raspberry Pi Pico to drive a VGA/TV display. PicoVGA was designed by Miroslav Nemecek.

The RP2040 processor contains 264 KB of RAM. This is not much for higher resolution image output and therefore RAM needs to be very sparing. In technical practice and for retro games (the processor does not have the power for more advanced games), 8-bit graphics output in R3G3B2 format (i.e. red 3 bits, green 3 bits and blue 2 bits) is fully sufficient. Output in 16 or 24 bits is not meaningful in normal practice, as the Raspberry Pico does not have enough memory or power to provide such large amounts of data in areas other than short demos. Using the dithering technique, interesting display results can be achieved even with 8-bit output.

PicoVGA diagram.jpg

Software

The PicoVGA library is written in C/C++ and allows output from the Raspberry Pico to a VGA monitor or PAL/NTSC TV, with a focus on ease of use in technical and gaming applications. It provides 4 graphic overlay layers with transparency, nearly 30 frame buffer formats that can be freely combined with each other, making do with limited RAM memory size. The limitation of output to 8 bits also contributes to RAM saving.

Features

  • 1 base layer and 3 overlay layers with transparency
  • 8-bit output in R3G 3:3:2 format
  • VGA progressive output up to 1280x960 resolution
  • TV output in PAL or NTSC interlaced mode
  • 30 frame buffer formats: graphics, tiles, text, special
  • Colour palettes
  • Screen split into segments of different formats
  • RLE compression
  • Transparency with selectable key colour
  • Hardware sprites
  • Output layers to different color bits (color planes)
  • Automatic configuration video mode timings
  • Automatic overclocking of processor
  • Library uses the 2nd core, main program uses 1st core
  • PWM mono audio output
  • Joystick connector(S)

Connectors

J1/J3 Pico breakout

PicoVGA1 J1 J3.PNG

J2 - Mono Audio

J4 - 5V USB B

J5 - Joystick

  • 1x12 Header matches pinout of JOYPAD card

RasPiPico VGA J5 JOYPAD.PNG

// Init the JoyPad pins
// #define PB_UL 16		// Upper Left pushbutton
// #define PB_RT 17		// Right direction
// #define PB_FR 18		// Fire
// #define PB_LT 20		// Left direction
// #define PB_CF 21		// Center Fire
// #define PB_DN 22		// Down direction
// #define PB_UR 26		// Upper right
// #define PB_UP 27		// Up direction

Joystick (DB-9)

RasPiPico VGA J6 JOYSTICK.PNG

MSX Joystick Schematic Circuit 382px.png

  1. UP
  2. DOWN
  3. LEFT
  4. RIGHT
  5. +VCC
  6. BUTTON I
  7. BUTTON II
  8. BUTTON COMMON
  9. GND

Prototype Build Hardware

PicoVGA P1080432-720px.jpg

Raspberry Pi Pico Breakout Card

RasPiPico.PNG

VGA Adapter Card

VGAX49 P901-cropped-720px.jpg

RasPiPico VGA J1.PNG

RasPiPico VGA Wiring.PNG

Audio Filter Card

RasPiPico AUDIO Wiring.PNG

Joy Stick (JoyPad)

P1826-CROPPED-720PX.jpg

Prototype Build Wiring

Pico Pin GPIO Signal Name Color Dest Pin
1 GP0 B3 BLU VGAX49 13
2 GP1 B4 BLU VGAX49 12
3 GND GND BRN VGAX49 20
4 GP2 G3 GRN VGAX49 8
5 GP3 G4 GRN VGAX49 7
6 GP4 G5 GRN VGAX49 6
7 GP5 R2 RED VGAX49 3
9 GP6 R3 RED VGAX49 2
10 GP7 R4 RED VGAX49 1
11 GP8 CSYNC GRY VGAX49 17
21 GP16 BRN JOYPAD 10
22 GP17 ORG JOYPAD 9
23 GND GND GRN AUD-FILT 2
24 GP18 YEL JOYPAD 8
25 GP19 AUDIO GRY AUD-FILT 1 or 3
26 GP20 GRN JOYPAD 7
27 GP21 BLU JOYPAD 6
28 GND GND BLK JOYPAD 11
29 GP22 VIO JOYPAD 5
31 GP26 GRY JOYPAD 4
32 GP27 WHT JOYPAD 3