Well, I just found out some errors in my part ii Fuel Load Indicator addendum interface table.  Apparently, I was using the wrong part's pinout, "So without further eloquence"1, here are the new tables.

 

Signal TypeSignal Color
Data Lines
Address Lines
Control Lines U1
Control Lines U2

Notes:

  • U2 is closest to the off-board connector.
  • Both Logic Ground and Supply Ground are tied together.
  • In the connector table, a 0 at the end means it is LOW ACTIVE

Comments:

  • For some unknown reason, the designer chose to separate all  for control signals for U1 and U2  (He should find his way to engineer hell)
  • CLS1 and CLS2, Clock Select, are tied together and pulled HIGH for internal Clock
  • CLK1 and CLK2, Clock, are tied together and  pulled high
  • RST10 and RST20, Reset, are tied together and  pulled high
  • WR10 and WR20, Write,  are tied together and  pulled high ( I am still looking for WR20)
  • RD10 and RD20, Read, are tied together and pulled high.
  • FL10 and FL20,  Flash, are tied together and pulled high.
  • CE10 and CE20, Chip Enable, are not tied together and pulled up high.

 

HDSP 2131 Pinout
PinSignal NamePinSignal Name
1CLS32A4
2CLK31A3
3WR30A2
4CE29A1
5RST28A0
6RD27FL
7NO PIN26NO PIN
8NO PIN25NO PIN
9NO PIN24NO PIN
10NO PIN23NO PIN
11D022D7
12D121D6
13D220D5
14D319D4
15NC18GRD (LOGIC)
16VDD17GND (SUPPLY)

 

Connector
TOP24681012141618202224262830
BOTTOM1357911131517192123252729
KEYWAY

 

 

 

 

 

 

 

TOP ROW
PINSignal NameU1U2
2VDD1616
4VDD1616
6RST20-5
8FL127-
10FL2-27
12CE104-
14RD20-6
16WR103-
18CLS11-
20D41919
22D21313
24D11212
26A12929
28A33131
30A23030
BOTTOM ROW
PINSignal NameU1U2
1GND1717
3GND1818
5RST105-
7CLK11-
9CLK2-2
11RD106-
13CE20-4
15CLS2-1
17D72222
19D62121
21D52020
23D31414
25D01111
27A43232
29A02828


For testing, I plan I just hooking one a display and run it. After if there are no more errors, I then can interface it via I2C.

 

Refs

1. The Quiet Man, 1952, IMDb  as spoken by Barry Fitzgerald