Re: 8 bit vs 32 bit
There is some more information:
The right microcontroller selection is based on the combination of on chip peripherals, memory size, I/O match the system requirements, performance, the cost, power consumption, development time and availability of good development tools.
The actual core preference takes the lowest percentage.
Software development, debugging and maintain are the primary drivers of project cost and schedule. The key criteria here is the project reuse, the ability to spread the software development investment across multiple products.
Adapting off-the-shelf solution reduces development time. Industrial control applications, where 8 bit micros are very popular, fall into this category, since the volumes are high. Moving to high level programming languages and robust development tools, enable the software reuse.
Modern 32 bit microcontrollers enable optimizing the architecture using powerful debugging tools minimizing the need for assembly code.
Power consumption:
Selecting a microcontroller requires an evaluation of power consumption of both active and standby. CPU core is a very small contributor to total active power consumption when peripherals, memory and I/O are considered. Looking at the 8 bit and 32 bit architectures, it is clear that 32 bit SoC are very hungry for power because of the powerful CPU and everything else on chip.
The average power consumption though is the duty cycle time spent in sleep mode and active mode.
Because 32 bit operates faster, it can execute a task and go back to sleep much faster then an 8 bit one. Hence spending more time in standby mode and saving more power.
Code size:
As know CISC CPU consumes less program memory then RISC. However, good 32 bit compilers generate less code, hence using less program memory.
Looks like the conclusion, is to go for 32 bits even if the application is low-end.
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