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

J2 - Mono Audio

J4 - 5V USB B

J5 / J6 - Joystick

MSX Joystick Schematic Circuit 382px.png

  1. UP
  2. DOWN
  3. LEFT
  4. RIGHT
  5. +VCC
  6. BUTTON I
  7. BUTTION II
  8. BUTTON COMMON
  9. GND
// #define PB_RT 16
// #define PB_LT 17
// #define PB_CF 18
// #define PB_DN 20
// #define PB_UR 21
//	keyboard control: 
//		'L' right, RT - BRN - RIGHT
//		'I' turn, CF - YEL - CENTER FIRE ROTATE
//		'J' left, LF - ORG - LEFT
//		'K' drop, DN - BLU - DOWN
//		'A' pause UR - GRY - UPPER RIGHT

Prototype Hardware

PicoVGA P18425-720px.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

Wiring

Pico Pin Signal Name Color Dest Pin
1 B3 BLU VGAX49 13
2 B4 BLU VGAX49 12
3 GND BRN VGAX49 20
4 G3 GRN VGAX49 8
5 G4 GRN VGAX49 7
6 G5 GRN VGAX49 6
7 R2 RED VGAX49 3
9 R3 RED VGAX49 2
10 R4 RED VGAX49 1
11 HSYNC GRY VGAX49 17
23 GND GRN AUD 2
25 AUDIO GRY AUD 3