hahahahaahah
OK, basically I wanted the GSM to be fully independent, because that's how i can leave the delay(5000) away from the main CPU.
Next, display is just for fancy branding issue... so let it be separate from main CPU again...
Motor controlling can be done with main CPU though there will be lots of sensors.
I have been thinking to go like this:
Display via i2c [sub system]
SD card writing of log entries via SPI [under direct main CPU]
Ethernet (if any) will be by SPI [under direct main CPU]
GSM will be either Serial (hardware or software that is the question) or any other method including i2c [sub system]
Motor to be controlled via main CPU.
What you guys say??
(The purpose is to let the CPU to focus on events instantly ASAP instead of getting blockd by the delay(xxx) ffor that GSM.
Mishu~