CPLD Board

This is the CPLD board used to socket the EPM7128SLC84 chip ...

This board is shared through OSH Park website.

I do not have any more info about this board .. but since I was going to design a similar one .. this one is fine and is very simple design. Can be used in standalone mode for programming EPM7128's .... or use the board as a shield that can later be plugged onto a mother type board via the 2 x40 pin connectors.

For retro microcomputer board use we only need the +5V function so there is no need for 3.3V regulator if you are not going to use that voltage. Also board can be powered directly by +5V with appropriate bridging link (not to use onboard +5V regulator).. see later pics. Similarly if you are not using any master clocks ... you do not need a crystal oscillator part of the board.

Top and bottom view of the board (blank) .. click to enlarge

Minimal Construction of Board

Here is partly constructed board containing:

• PLCC socket and EPM7128SLC chip

• JTAG socket pins

• Few bypass capacitors on +5V and Vio pins

• +5V Led indicator

• +5V Input terminal (in place of regulator output)

• 2 x 40 pin expansion and I/O pins from the chip

Following shows a VHDL application of an INVERT gate on the CPLD chip. Input pin is pin 33 ... and output pin to light an LED is pin 75.

INVERT VHDL code

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

USE IEEE.STD_LOGIC_UNSIGNED.ALL;

entity invert is

Port ( PB0 : in STD_LOGIC;

LED6 : out STD_LOGIC);

end invert;

architecture Behavioral of invert is

begin

-- invert the signal from the push button switch and route it to the LED

LED6 <= not(PB0);

end Behavioral;

Following is 2 pics of the bottom RH switch switching from low to high and the LED changing (H4)...

The great thing about this board and CPLD chip is that it operates on +5V voltage levels and hence great for interfacing as glue logic in retro board constructions.