MorganS:
So there must be one master in your proposal? Some slaves are write-only (display) but most will have data to give to the master when requested?How far apart are these devices? I2C works for short distances up to 1m or so. SPI can work pretty well up to a few meters. RS232 works up to 100m but only if within the same building. RS485 can go kilometers.
These days, wireless radios are cheaper than buying 10m of cable. Have you considered one of the mesh network radios such as the NRF24 or Xbee?
It will be within the board or max, a board beside. Basically there will be a large Motherboard with different subsections.
as said, there will be actually kinda multi master. Consider the following:
A separate configuration window (CLI/GUI) will be used to config the system (aka main CPU). Like allowed mobile number, etc. This will also make the master decisions and notify the subsystems about it. Thus this CPU will hold all the configuration of the whole system.
Each subsystem (like GSM controller) will be independent (like if GSM momdule is bootup, or no power, then the subsystem controller will issue bootup. Hence subsystem controller will send it's master (parent/CPU) the notification that GSM is down (so master will not issue any SMS outgoing if any). Once GSM module is registered and ready to operate, the subsystem controller will notify the CPU that GSM is ready. Hence GSM part will be dealt by the main program afterwards.
Now, if a SMS comes, GSM controller will send the SMS to main CPU in a formatted way so the content and sender info can be stripped. And if it is allowed from config, then main CPU will issue next order to the another subsystem say Motor controller. And that subsystem will independently work and report back on status to main CPU.
See, thus it's like a multi master type (in my eyes). Consider it like a multi task and each task has a different sub controller.
No way for wireless. All will be in board or max, board to board.
ard_newbie:
A CAN bus might be a solution.
I was thinking of the same but the thing is, consider it like a inter motherboard with bios, RAM, bla bla bla... I mean several subsystem will make a interconnected network inside the board. So hardware design is an issue also here.
Also, I cant rely on all the available sheilds as the device have to be really robust. My last experience with shields is worse than ever...
Ideas????