Good morning everyone,

Is there any advanced reference material on Stern SAM CPU board ?

I'm specifically looking at block diagram, data flow, etc...

I have looked into the schematics, and I'm trying to make head and tails (plus I think my schematics is missing a section, there's something odd on sheet 1 - I'm using Indiana Jones manual, which has the complete yellow pages...)

I've located the audio section, what I believe the DMD section as well as the memory/flash section.

What's rather complicated to understand is how the main CPU interacts with switchs/coils/etc... it seems the data bus are multiplexed, probably to reduce pin count. I believe the key area is actually page 2, where J9 is located, and all other connectors.

What I'm struggling to understand is as follows:
- what is the FPGA purpose, besides DMD display
- this is a high risk design, sharing a bus for both data output (inserts/coils) and input (switch) seems risky. But since SAM is considered as quite robust, I must have missed something in how it operates

Ultimately, I'd like to understand data output protocol on J9, that's my main focus

If anyone has any expertise on this subject and is willing to participate, I would welcome a discussion

Regards

Ah yes, he developed the TLS kit. But I think he focused mostly on switches/inserts readouts, not so much on the CPU/driver board interface, no ?

Reviving this thread

I will hook up a logic analyzer on the data bus to try to understand what's happening. I would welcome some assistance along the way to discuss further, if there are engineers here willing to participate

Goal is to document on a github how this bus operates, so that the information could be used to build interesting mods on Stern SAM machines

Cheers

Well, I must admit I did know about that But same question apply though, if you have a pointer to Stern Whitestar databus protocol, that would be useful

That said, I've been looking at the schematics, and on paper it seems relatively straightforward. A 4 bit adress, 8 bit data bus, with decoder which allow to select three solenoid banks, flasher and lamp from what I understand. Still need to understand more on how this operates as a whole, but that does not seem overly complicated, unless I'm missing something

Link to github with the result of my analysis of the Stern SAM schematics (I did not even need to hook up a Logic Analyzer, although I will need to at least to know which speed we're talking about)

https://github.com/Ashram56/Stern-SAM-Databus-Analysis