Thank you Alan for leading this great initiative and everyone paritcipating :-)
Sorry I was on the trip yesterday, could only for a moment on a train station, then I lost connectivity :-( This DIMM DDR2 SO-DIMM connector is nice for the CPU board aka "compute module" using similar connectors :-) The only problem I see here is radio antenna connectivity this is always pain in the butt :-P I can see Sebastien commented about 1mm thickness of the PCB but this is not a problem this is standard thickness easy to manufature at home too :-) I use often 0.5mm 1.0m 1.5mm :-) Factories now can make 10 layers, flexible, translucent, all sorts of magic :-) Then the mainboard can be easily extended / replaced / upgraded for what is needed. For a long time (since ~1997) I am using this modular approach for various initial prototypes, where each chip has its own board and connectors that can be then connected with other boards breadboards etc. Its very popular nowadays :-) One question - do we want to solder chips on the mainboard or just provide conenctors for the chip-board? Having everything as module would make mainboard cheaper to manufacture, faster to solder, also chip cpecific boards will be faster and cheaper to manufacture, and most of all we would easily reconfigure / upgrade mainboard peripherals when needed even without soldering - we can then replace just one small board when needed. One disadvatage is signal integrity for high speed bus.. but it would be better than loose wires anyways :-) It would be nice if all boards are designed in a way they can be manufactured at home :-) I have pretty good LPKF cnc for pcb so I can test two layer/side designs. But also pcb making with laser printer toner transfer should be possible. Thus some DRC rules would be nice to define such as minimum track width 0.5mm etc :-) Probably for CPU board these will be smaller due to quite dense connector? We could then produce gerber / drill / cut files for the boards, pack them up on a single layout, and send to factory to get a bundle like 5x for low cost and then solder things up at home? Maybe ordering already soldered boards can be cheap too. It would be good to provide cos simulation from various places when things are ready :-) Thanks again! :-) Tomek On Sun, Sep 7, 2025 at 10:06 PM Alan C. Assis <[email protected]> wrote: > > Hi Everyone, > > Thank all participants of the meeting about the NuttX Standard Board. > > For those who were unable to attend, the video is available on YouTube: > https://www.youtube.com/watch?v=keZAZ8GiYzI > > Just a summary of our meeting today: > > - It was defined that we should use the DIMM DDR2 SO-DIMM. > Pros: It has 200 positions (pins); Low Cost; Easy to solder manually; The > CPU/MCU Modules don't require a connector. > Cons: the CPU/MCU module needs to use ENIG ( > https://en.wikipedia.org/wiki/Electroless_nickel_immersion_gold) that is a > little bit more expensive than simple PCBs > > - In order to simplify the base board routing and avoid complexity some > high speed interfaces (LCD, Ethernet) will be in the CPU/MCU Module. (but > the signals will be available in the connector (TBD)) > Pros: Simplify the board design; Avoid rigid rule of have only a single > Ethernet's PHY or LCD module tested all the time; > Cons: The CPU/MCU Module will end-up becoming more expensive because these > extra components > > - The Mainboard/Baseboard will have the most common sensors/peripheral > soldereds in the board and an expansion connectors (i.e. MicroBUS, P-MOD, > MicroMOD, etc) to let users/developers test other devices. > Pros: Reduce final cost; Brings more flexibility > Cons: Increase the board size to support these expansion connectors. > > We should have a new meeting next week (Sunday) to decide which devices we > will include in the board, if you have suggestions to improve our board, > please participate. > > BR, > > Alan > > On Sun, Sep 7, 2025 at 9:14 AM Alan C. Assis <[email protected]> wrote: > > > Hi Everyone, > > > > For those who will participate in the design phase, please join in the > > Jitsi, we will start in 45min: > > > > https://meet.jit.si/Developing_NuttX_Standard_Board > > > > BR, > > > > Alan > > > > On Sat, Sep 6, 2025 at 11:57 AM Alan C. Assis <[email protected]> wrote: > > > >> Hi Everyone, > >> > >> We will have tomorrow morning (afternoon/evening for merians A to M) our > >> first meeting about the NuttX Standard Board: > >> > >> https://www.youtube.com/live/keZAZ8GiYzI > >> > >> New to this subject? Ref: > >> https://github.com/NuttX/nuttx_hardware/blob/main/Documentation/standard/index.rst > >> > >> Please join us to define which features we need to have in this board. > >> > >> BR, > >> > >> Alan > >> > > -- CeDeROM, SQ7MHZ, http://www.tomek.cedro.info
