Author Topic: I2C multiplex 4 atmega328p standalone chips to use one OLED screen  (Read 1481 times)

Offline adriaanhendrik

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Hi all,

I am working on a project that uses several ATMega328p chips with 5 ' IIC I2C OLED Display Module 12864 LED '
The display module works on I2C channel 0x3c. Each of the chips is controlled by a Rotary encoder and produces MIDI Exclusive data.
The library i use is for Adafruit_SSD1306 displays and works fine.

On the front panel of this controller I have space for only 5 displays.
I would like to use one of the displays to output the data for 4 additional chips using the I2C multiplexer board.
Leaving the first four displays to function like they are now. I have a total of 8 chips producing MIDI exclusive data for a YAMAHA CBX-D5 audio processor enabling it to work standalone in my sound studio.

I have connected everything according to the schematic I found in the datasheet of the PCA9544A and I wonder if I will have to use the Address pins to choose which chip can display it's data or just the Interrupt inputs I0 - I3 ?
A0 - A3 are connected to earth as in the schematic of the datasheet but i suspect this might be wrong for my purpose..

As I understand it, the multiplex board can be used with 4 I2C streams using the aforementioned 0x3c that the display works on and sends the chosen chip data to the 5th display module.

I have attached an arduino scetch with an atempt to address the board. It is my aim to select the I0 - I3 with the push switches of the encoders using a hardware interrupt to select which chip will display it's data on the display module.

added to the post later:

OK after some trying I got it to work as a 1 in 4 out module, but that is exactly the other way around.. :(
So how do I code 4 masters in 1 slave out ??
I added the sketch with the code so far


« Last Edit: April 04, 2016, 05:10:22 PM by adriaanhendrik »