This is revision A of the EMDP1 GAL28 plug and it is currently a work in progress.

EMDP1 GAL28 Plug (Rev. A)

Table of Contents
Introduction
Schematic
Printed Circuit Board
Tables
Issues

Introduction

The EMDP1 GAL28 plug is used to program the 16V8 and 18V10 20-pin GAL's.

Schematic

The schematic for this revision is shown below:

Printed Circuit Board

The following printed circuit board files exist:

gal28_artwork.png: The artwork layer picture (PNG).
gal28_back.png: The back layer picture (PNG).
gal28_front.png: The front layer picture (PNG).
gal28.gal: The artwork Gerber (RS274X) file.
gal28.gbl: The back (solder side) Gerber (RS274X) file
gal28.gtl: The front (component side) Gerber (RS274X) file.
gal28.gml: The mask (both sides) Gerber RS274X) file.
gal28.drl: The drill (Excellon) file.
gal28.tol: The tool file that lists hole counts.

Tables

The table below shows were each of the BD signals winds up:

ZIF
Pin GAL
Pin 26CV12 EMDP1
Plug
1 1 VIL BD23
2 2 EDIT VAR2
3 3 P/V- BD21
4 4 RA0 BD2
5 5 RA1 BD4
6 6 RA2 BD6
7 7 VCC VAR1
8 8 VIL BD8
9 9 RA3 BD7
10 10 RA4 BD10
11 11 RA5 BD12
12 12 SCLK BD14
13 13 SDIN BD16
14 14 STB- BD18
27 15 SDOUT BD19
28 16 VIL BD17
29 17 VIL BD15
30 18 VIL BD13
31 19 VIL BD11
32 20 VIL BD9
33 21 GND GND
34 22 VIL BD5
35 23 VIL BD3
36 24 VIL BD1
25 37 VIL BD0
38 26 VIL BD22
39 27 VIL BD20
40 28 VIL R1 Pull Down

ZIF Pin	GAL Pin	26CV12	EMDP1 Plug
1	1	VIL	BD23
2	2	EDIT	VAR2
3	3	P/V-	BD21
4	4	RA0	BD2
5	5	RA1	BD4
6	6	RA2	BD6
7	7	VCC	VAR1
8	8	VIL	BD8
9	9	RA3	BD7
10	10	RA4	BD10
11	11	RA5	BD12
12	12	SCLK	BD14
13	13	SDIN	BD16
14	14	STB-	BD18
27	15	SDOUT	BD19
28	16	VIL	BD17
29	17	VIL	BD15
30	18	VIL	BD13
31	19	VIL	BD11
32	20	VIL	BD9
33	21	GND	GND
34	22	VIL	BD5
35	23	VIL	BD3
36	24	VIL	BD1
25	37	VIL	BD0
38	26	VIL	BD22
39	27	VIL	BD20
40	28	VIL	R1 Pull Down

This particular plug ran out of pins. Thus, pin 40 of the ZIF, is attached to ground via a 10K ohm pull down resistor. This is an alternative whereby we use SDO as an extra output. I went with the former.

Issues