Analysis:
The first hurdle is that an Arduino has only GPIO pins but you can not get to a bus from here, without a lot of bit-banging by the CPU.
Second, the Displays are smart devices and designed to have both Address and Data Buses.
The only thing is to use an I2C peripheral expander. The only problem is that the I2C bus limits to about 1 meter.
The Plan:
I will wire the MCP23017 to the display board as follows:
| MCP | Pin | Display | Pin |
| Data Bus | |||
| GPA0 | 21 | D0 | 25 |
| GPA1 | 22 | D1 | 24 |
| GPA2 | 23 | D2 | 22 |
| GPA3 | 24 | D3 | 23 |
| GPA4 | 25 | D4 | 30 |
| GPA5 | 26 | D5 | 26 |
| GPA6 | 27 | D6 | 29 |
| GPA7 | 28 | D7 | 8, 10 |
| Address Bus | |||
| GPB0 | 1 | A0 | 19 |
| GPB1 | 2 | A1 | 21 |
| GPB2 | 3 | A2 | 20 |
| GPB3 | 4 | A3 | D3 |
| GPB4 | 5 | A4 | 1 |
| Arduino | Pin | ||
| SDA | 13 | 20 | |
| SCK | 12 | 21 | |
| RST | 181 | ||
I will need to drive the control Lines from the Arduino itself
| Control Lines | ||
| Mneumonic | Display Pin | Arduino |
| RST1 | 5 | 23 |
| RST2 | 6 | 24 |
| CE1 | 12 | 25 |
| CE2 | 13 | 26 |
| CLK1 | 7 | 27 |
| CLK2 | 9 | 28 |
| RD1 | 11 | 29 |
| RD2 | 14 | 30 |
| CAN Module | ||
| CS | 10 | |
| SO | 12 | |
| SI | 11 | |
| CLK | 13 | |
| INT | 2 | |
Parts List:
| Switches | ||
| Mneumonic | Display Pin | Arduino |
| Up | 12 | 31 |
| Down | 2 | 32 |
| Common | 3 | |
| Fill | 4 | 33 |
| Test | 5 | 34 |
-
- Interface PCB to hold parts and to interface to the display board
- 30-pin (2x15) Female header with Wire-Wrap
tails. (Samtec SSQ-115-04-L-D) - 2 14-pin Augat turned pin, low profile IC sockets with Wire-Wrap tails (Augat MBL5-14F).
- 1 MCP23017-E/SPMCP23017-E/SP 16-bit I2C peripheral expander which is organized into 2 8-bit bi-directional ports.
Notes:
-
- Pulled up via a 10kΩ resistor.
- Pin 1 is by the white dot
Using Port-Manipulation:
- Port A: 10 -> 7 Data Port (See Table on left D0 -> D7)
- Port L: 0 -> 5 Address Lines A0 -> A5
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