MCU-128 Backpanel

24 Jul 2021

PROBLEM:
I have been struggling to find a solution to a mess that has stopped me from doing much with this project. The interconnection is weird 0.025" square, on a 0.1" center. Nothing fits this dam thing to make matters worse there are no manufacture part numbers

After being on the phone with AMP customer support and then he wants pictures, oh no. In my desperation, I called Samtec.

SOLUTION:
Guss what this damn thing is a standard connector. They are sending me a bunch of the little sobs. So I found out that I was looking for the TSW Series. I needed headers with the following configurations: 2, 8, 9, 14, 17. So the part number works out to TSW-1xx-07-F5 where xx are the pin counts.

THE PLAN:

W6P1	1	2	3	4	5	6	7	8	9
W6P2	10	11	12	13	14	15	16	17
W6P3	18	19	20	21	22	23	24	26
W6P4	27	28	29	30	31	32	33	34
W6P5	35	36	37	38	39	40	41	42
W6P6	43	44	45	46	47	48	49	50
W6P7	52	53	54	55	56	57	58	59
W6P8	60	61	62	63	64	65	66	67	68
W6P9	10	11
W7P1	1	2	3	4	5	6	7	8	9	10	11	12	13	14
W7P2	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
W7P3	33	34	35	36	37	38	39	40	41	42	43	44	45	46	Thumbwheel Switch [H, 1 through 0]
W7P4	47	48	49	50	51	52	53	54	55	56	57	58	59	60	61	62	63	64
W7P5	1	2	3	4	5	6	7	8	9	10	11	12	13	14
W7P6	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
W7P7	33	34	35	36	37	38	39	40	41	42	43	44	45	46
W6P8	47	48	49	50	51	52
W5P1
W5P2	20	19	18	17	16		Thumbwheel Switch [H, 1 through 0]
W5P3
W5P4
W5P5	20	19	18	17	16	15	14	Thumbwheel Switch [PH, 1 through 0] 14 & 15 lighting
W5P6
W5P7
W5P8	11	10	9	8	7		Relay Bot used
W5P9	20	19	18	17	16	15	14	13	12	Mode Switch 18C 20 [power on]

So as you can see from the table on the left, the connectors above the red line, W6P1 through W6P9 are for the four (4) hex-a-decimal displays.
The connectors below, W7P1 through W7P8 are for the thirteen (13) 7-segment displays.

The 185 pins will be connected to four (4) 50 pin male headers. Since I have no idea of which wire is which. So far this takes care of the displays. Now all that is left is to figure out the keyboard. I do believe it is a matrix keyboard of some sort. I will be using the MCP23017 I/O Expander for the dirty work. It is very nice and has INTA and INTB. this lends itself to all of the switches and the keyboard will be interrupt-driven.

Consider if I roll my own interrupt controller. There are 4 switches, plus the keyboard, that I have to contend with, 4 i/o expanders.

and 5 or 6 interrupts. Since the Arduino Mega has really on 4 useable interrupt pins I will take the interrupts from IC1A, 1B, 2A, 2B are inputs to an MCP23017 IC3A and this interrupt will go to one interrupt handler. When the interrupt handler is called you look at its data which will tell you which switch data to look at.

One more MCP23017 will handle Keyboard, Microchip's AN101 describes via an interrupt. That leaves one for Communications.

Display Connectors

W6P1	1	3	5	7	9	11	13	15	17	19	21	23	25	27	29	31	33	35	37	39	41	43	45	47	49
W6P2	1	3	5	7	9	11	13	15	17	19	21	23	25	27	29	31	33	35	37	39	41	43	45	47	49
W6P3	2	4	6	8	10	12	14	16	18	20	22	24	26	28	30	32	34	36	38	40	42	44	46	48	50
W6P4	2	4	6	8	10	12	14	16	18	20	22	21	26	28	30	32	34	36	38	40	42	44	46	48	50
W6P5
W6P6	1	3	5	7	9	11	13	15	17	19	21	23	25	27	29	31	33	35	37	39	41	43	45	47	49
W6P7	1	3	5	7	9	11	13	15	17	19	21	23	25	27	29	31	33	35	37	39	41	43	45	47	49
W6P8	2	4	6	8	10	12	14	16	18	20	22	24	26	28	30	32	34	36	38	40	42	44	46	48	50
W6P9	2	4	6	8	10	12	14	16	18	20	22	24	26	28	30	32	34	36	38	40	42	44	46	48	50
W7P1
W7P2	1	3	5	7	9	11	13	15	17	19	21	23	25	27	29	31	33	35	37	39	41	43	45	47	49
W7P3	1	3	5	7	9	11	13	15	17	19	21	23	25	27	29	31	33	35	37	39	41	43	45	47	49
W7P4	2	4	6	8	10	12	14	16	18	20	22	24	26	28	30	32	34	36	38	40	42	44	46	48	50
W7P5	2	4	6	8	10	12	14	16	18	20	22	24	26	28	30	32	34	36	38	40	42	44	46	48	50
W7P6
W7P7	1	3	5	7	9	11	13	15	17	19	21	23	25	27	29	31	33	35	37	39	41	43	45	47	49
W7P8	1	3	5	7	9	11	13	15	17	19	21	23	25	27	29	31	33	35	37	39	41	43	45	47	49
	2	4	6	8	10	12	14	16	18	20	22	24	26	28	30	32	34	36	38	40	42	44	46	48	50
	2	4	6	8	10	12	14	16	18	20	22	24	26	28	30	32	34	36	38	40	42	44	46	48	50

Switch Connectors

FLY-TO			DEST				Mode Switch					Display Switch					reserved for kbd
W5P2			W5P5				W5P9										W5P1 - W5P4
1	3	5	11	13	15	17	21	23	25	27	29	31	33	35	37	39	41	43	45	47	49	pins
1	3	5	11	13	15	17	21	23	25	27	29	31	33	35	37	39	41	43	45	47	49	connector J5
2	4		12	14	16		22	24	26	28		32	34	36			42	44	46	48	50	connector J5
2	4		12	14	16		22	24	26	28		32	34	36			42	44	46	48	50	pins
4		C	4				6			C2	1	7				C
IC1A			IC1B				IC2A				2A	IC2B					IC3

dougw over 3 years ago in reply to phoenixcomm

Yep, I only have good things to say about Samtec.
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phoenixcomm over 3 years ago in reply to DAB

DAB thanks, the guy at AMP was dumber than a rock, it was a close tie with Trump The Samtec guy knew what it was when I said the pin was 0.025" square!!
~~ Cris
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DAB over 3 years ago

Nice job of tracking down the connectors.

One of my first engineering projects was tracking down odd connects.
Luckily they were still available, but in todays world, they become obsolete almost over night.

DAB
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