1300 Henley Court Pullman, WA 99163 509.334.6306 www.store. digilent.com Pmod VGA Reference Manual Revised January 22, 2018 This manual applies to the Pmod VGA Rev. C Overview The Pmod VGA (Rev. C) provides a VGA port to any board with Pmod connectivity. The VGA port can be used to drive standard displays such as televisions and monitors. The host board must be capable of driving a fast parallel data bus in order to properly drive a display with the Pmod VGA. Standard VGA port for connecting commonly found displays 12-bit RGB444 color depth Simple, high-speed R-2R resistor ladder DAC High-speed buffers support pixel clocks up to 150 MHz The Pmod VGA. 1 Specifications Pin Signal Description 1 R0 Red 0 2 R1 Red 1 3 R2 Red 2 4 R3 Red 3 5 GND Power Supply Ground 6 VCC3V3 Positive Power Supply 7 B0 Blue 0 8 B1 Blue 1 9 B2 Blue 2 10 B3 Blue 3 11 GND Power Supply Ground 12 VCC3V3 Positive Power Supply Table 1. Pmod header J1. Copyright Digilent, Inc. All rights reserved. DOC : 410-345 Page 1 of 5 Other product and company names mentioned may be trademarks of their respective owners. Pmod VGA Reference Manual Pin Signal Description 1 G0 Green 0 2 G1 Green 1 3 G2 Green 2 4 G3 Green 3 5 GND Power Supply Ground 6 VCC3V3 Positive Supply Ground 7 HS Horizontal Sync 8 VS Vertical Sync 9 NC Not Connected 10 NC Not Connected 11 GND Power Supply Ground 12 VCC3V3 Positive Power Supply Table 1. Pmod header J2. 1.1 Physical Dimensions The pins on the pin header are spaced 100 mil apart. The PCB is 1.7 inches (4.3 cm) long on the sides parallel to the pins on the pin header and 1.7 inches (4.3 cm) long on the sides perpendicular to the pin header. 2 Functional Description The Pmod VGA uses 14 input pins to create an analog VGA output port. This translates to 12-bit color depth and two standard sync signals: Horizontal Sync (HS) and Vertical Sync (VS). The digital-to-analog conversion is done using a simple R-2R resistor ladder. The ladder works in conjunction with the 75-ohm termination resistance of the VGA display to create 16 analog signal levels for the red, blue, and green VGA signals. This circuit produces video color signals that proceed in equal increments between 0V (fully off) and 0.7V (fully on). With 4 bits each for red, blue, and green, 4096 (16x16x16) different colors can be displayed, one for each unique 12-bit pattern. When used with an FPGA host board, a video controller circuit must be created in programmable logic to drive the sync and color signals with the correct timing in order to produce a working display system. It may be possible to drive the video signals using a very fast microcontroller with a parallel bus controller however, Digilent does not provide examples for this use case. 2.1 Interfacing with the Pmod VGA signal timings are specified, published, copyrighted, and sold by the VESA organization (www.vesa.org). The following VGA system timing information is provided as an example of how a VGA monitor might be driven in 640 by 480 mode. NOTE: For more precise information, or for information on other VGA frequencies, refer to documentation available at the VESA website. CRT-based VGA displays use amplitude-modulated moving electron beams (or cathode rays) to display information on a phosphor-coated screen. LCD displays use an array of switches that can impose a voltage across a small amount of liquid crystal, thereby changing light permittivity through the crystal on a pixel-by-pixel basis. Although the following description is limited to CRT displays, LCD displays have evolved to use the same signal timings as CRT displays (so the signals discussion below pertains to both CRTs and LCDs). Copyright Digilent, Inc. All rights reserved. Page 2 of 5 Other product and company names mentioned may be trademarks of their respective owners.