Month: December 2025

Heating Opentherm Boiler & HomeAssistant, meet the FusionBerry, part 1

This is the first post on this topic, and I wanted to share my lessons learned and also a project initiated a few month ago. The photo below is the first release of the FusionBerry up and running to manage an end to end open solution to manage Opentherm, Ethernet, MQTT, HomeAssistant boiler & heating solution.

It integrate perfectly with node red flows to fully manage the cycle (scheduler, TRV management, boiler order), but this will be another post soon.

The problem statement was how to manage, automate and optimize the heating system in my house with Home Assistant, opentherm boiler and multiple TRVs.

I spent hours to find the right approach, that brings efficiency, reliability and easy operation. I have tested many products on the market (netatmo, Legrand, deltadore). All excellent product, but sometimes blackbox, not open and flexible as I needed and also not addressing opentherm.

The main … Read the rest

Logic Analyzer & Apple II

Over the last few weeks, I have built several SmartDisk II, and I have been testing the hardware and the latest firmware release on my beloved IIGS.

The IIGS is very easy to work with, and loading GSOS 6.04 immediately reveals any timing issues.

Everything was fine until I received a message from a user explaining that some SmartDisks were working on the IIc Smartport and others were not, though all were working on the IIGS. 

I decided to sort this out, so I took all my 10 samples—and guess what? Half of them were not working on the IIc.

Finding the issue was like looking for a needle in a haystack, as the problem was not consistent.

I gathered my courage and reopened the engine. I spent endless hours trying to figure out what was not working.

I used my preferred logic analyzer, and for some reason the incoming … Read the rest

Resurrecting an IBM 8540 PSU

I finally was able to find an IBM PS/2 8540SX in a good esthetic shape with no plastic issue and all the very specific IBM screw on the back. The 8540 was one of the last (with the 8535) to be equipped with ISA bus and not the proprietary Micro Channel bus MCA. The is why, it is been highly chased by retro hunter.

In this case, this IBM was sold as not working and as it arrived the initial testing was not showing any sign of life.

The demand on this kind of computer is extremely high and almost with no offer at all, so when you see one appearing on the market one does not hesitate too long. The seller, was king enough to make the packaging strong to avoid any damages, especially on the plastic corners.

I was betting on the non starting root cause to be … Read the rest

SmartDisk II – The Origin

I remember the first time I had my first prototype of what will become the SmartDisk II loading the NIB image of BoulderDash II on my Apple II.

The first prototype was made on a very poor quality breadboard with a STM32 Bluepill, with a lot of ICs. The process to load NIB image was not really accurate, but I was so proud of having at least something working. 

This was the beginning of my journey to design and build an accurate Apple II Disk Emulator. I reached out to the Applefritter community for help on this project, and I received more than what I was hopping. This was a few month of long hardworking and debugging session with a lot of up and down along this way.

The purpose of this project was really a personal goal to experiment, learn, understand, and build. My approach from the beginning was … Read the rest

Smartloader for SmartDisk

I received a message on AppleFritter to add a new feature on the SmartDisk II. The request was to have the content of the SDCard to be displayed on the Apple II at startup like Slot card are able to do it. I did not reply straight because I was not sure it was possible or not. 

I started reflecting on how I would do it given my knowledge of the DISK II interface card and also the way the SmartDisk II is working. I had an interesting discussion with Antoine Vignau on an approach that would use the SMARTPORT protocol with undocumented function around CMD. With this approach the SmartDisk II would issue a SmartPort CMD with specific parameters that are not used by the SmartPort ROM or the SP6 Rom. I still think this is possible, however the approach would assume that the Apple II has a SMARTPORT … Read the rest