TEXT_DEMO

Arduino MKR VIDOR 4000 -- HDMI Text Screen demo

In this project

• Loading the FPGA directly into RAM instead of the external Flash.
• DVI OUT 640x360 (all the pixels are identical and square, both on 1280x720 screens and on 1920x1080 screens).
• Text format: 45 lines by 80 columns.
• Character format: 8x8 pixels.
• Each cell of the VideoRAM is made up of 18 bits.
• MCU-FPGA interface via SPI.

VideoRAM cell format

• Bits 17..16: Blink Attribute.

  • 00: Normal.
  • 01: Foreground Blink.
  • 10: Background Blink.
  • 11: Foreground & Background Blink.

• Bits 15..12: Foreground Color.

  • Bit 15: Full/Half brightness.
  • Bit 14: Red Component.
  • Bit 13: Green Component.
  • Bit 12: Blue Component.

• Bits 11..8: Background Color.

  • Bit 11: Full/Half brightness.
  • Bit 10: Red Component.
  • Bit 9: Green Component.
  • Bit 8: Blue Component.

• Bits 7..0: Character (used as an index in the CharROM).

SPI Commands

• WriteRAW: Writes 18-bit character sequences to VideoRAM.

  First byte: 0x80

  Second byte: The 4 most significant bits of the address are loaded into the 4 least significant bits of this byte.

  Third byte: The 8 least significant bits of the address.

  From the fourth byte: Sequence of characters to be written, each consisting of 3 bytes (Blink, Color, Char).

  Writing ends by setting the CS signal low.

• WriteChar: Writes a sequence of characters using the blink and color attributes of the previous writing.

  First byte: 0x81

  From the second byte: Sequence of characters, one byte per character.

  Writing ends by setting the CS signal low.

• SetLocation: Set the address for the following writes.

  First byte: 0x82

  Second byte: The 4 most significant bits of the address are loaded into the 4 least significant bits of this byte.

  Third byte: The 8 least significant bits of the address.

  It can be followed by a further command without the need to lower and raise the CS signal.

• SetAttribute: Set the Blink, Foreground, and Background attributes for the following writes.

  First byte: 0x83

  Second byte: The two least significant bins of this byte are used for the Blink attribute.

  Third byte: The most significant 4 bits are the Foreground, while the 4 least significant bits are the Background.

  It can be followed by a further command without the need to lower and raise the CS signal.

• Repeat: He writes the same character for Size times.

  First byte: 0x84

  Second byte: The 4 most significant bits of the Size parameter.

  Third byte: The 8 least significant bits of the Size parameter.

  Fourth byte: The character to be repeated.

The TEXT.ino file defines functions that use these SPI commands.