> I still think it would be better if we were to go the way of modular systems.
Modularity can be expensive, though. The unused IO soaks up pins and pushes you to bigger packages and up the SOIC/QFP/QFN/BGA chain. You add multiplexers and transceivers and buffers and so on. The traces take board space and layers and the connectors cost a big chunk of the BOM. Separate modules add SKUs and manufacture, assembly and inventory overhead, and the offboard interfaces take space, power and time.
Whenever you have any appreciable volume, it's almost always cheaper to integrate and demodularise, even before you consider the physical size and form factor of the device.
Otherwise all embedded systems would be made of dev boards wearing a hat. Now, yes, there are many systems that use something like a RPi Compute Module or a TI ControlCard, but once you crack a certain volume, it's an easy cost optimisation to "flatten" it into a single PCB.
And the one thing you do not want from designing around a module is the possibility that the supply of surplus OldPhone X3 mainboards or whatever dries up in two years and it turns out the new generation of modules are just a bit different.
Modularity can be expensive, though. The unused IO soaks up pins and pushes you to bigger packages and up the SOIC/QFP/QFN/BGA chain. You add multiplexers and transceivers and buffers and so on. The traces take board space and layers and the connectors cost a big chunk of the BOM. Separate modules add SKUs and manufacture, assembly and inventory overhead, and the offboard interfaces take space, power and time.
Whenever you have any appreciable volume, it's almost always cheaper to integrate and demodularise, even before you consider the physical size and form factor of the device.
Otherwise all embedded systems would be made of dev boards wearing a hat. Now, yes, there are many systems that use something like a RPi Compute Module or a TI ControlCard, but once you crack a certain volume, it's an easy cost optimisation to "flatten" it into a single PCB.
And the one thing you do not want from designing around a module is the possibility that the supply of surplus OldPhone X3 mainboards or whatever dries up in two years and it turns out the new generation of modules are just a bit different.