PM3295A OLED upgrade

[leogala]

I upgraded the back-light displays of my PM3295 with OLED displays (see thread https://www.eevblog.com/forum/testgear/philips-pm3295-and-pm3295a/), as few people seem to be interested I share my experience and the project.
I have to say that I finished the projects 3 months ago and I've already forgot some details.. . I'll try.

The displays are low cost displays coming from china with i2c interface:

https://www.aliexpress.com/item/1pcs-0-96-blue-0-96-inch-OLED-module-New-128X64-OLED-LCD-LED-Display-Module/32640627772.html?spm=2114.13010608.0.0.mKDtUG

The original LCD board makes use of a PCE2111 (attached datasheet) decoding a serial message and driving the five LCDs (see page 4 for the timing of the serial message). Unfortunately the serial messages are not documented neither on the scope service manual nor on the PCE2111 datasheet. I managed to reverse engineer the serial protocol, but I've not documented that, however you can understand what I discovered from the arduino source file attached.

The idea is to use an arduino to decode the messages and drive the LCDs.
I've included a schematic diagram and the arduino code. The code makes use of i2c library and adafruit library for the graphic display control.

It is interrupt driven, as soon as the message arrives an interrupt is triggered, the message is decoded and sent to the correct lcd.
While I was finishing the project I realized that arduino mini is a bit at its breaking point in terms of speed as the parser time is almost enough to process the next message when e.g. you roll the time base very fast, something faster could be better, anyway it works also with an arduino mini.

For the mechanical installation I developed a 3d-printed support (see stl included), it replace the original LCD board almost perfectly.

I know that the project is far from being well documented but I did it originally only for me and it works very well on my scope. I hope it can be of help for someone else.
I'm available to help anyone willing to try the project but please don't ask me to open again the scope...
 
Good luck
Leonardo