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How do I select a microcontroller with low power consumption?

-for MSP430 series we can compare using \$\mu\$A/MHz at active state.

Similarly how to compare this with other MCU's like PIC and STM series i.e. other MCU's provide \$\mu\$A/MHz @ diff speed and have DMIPS for performance and MSP430 series doesn't provide any DMIPS parameter.

If \$\mu\$A/MHz==\$\mu\$A/MHz for ARM and MSP430 is it good to select ARM, as ARM is 32 bit where as MSP is 16 bit MCU?

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First, you have to decide power consumption in which state matters for you.

There are several cases:

  • sleep-mode, possibly with some peripherals left running (an RTC, a timer, a PWM output, etc.)

  • very low-speed clock mode used instead of sleep-mode, with some peripherals left running

  • normal (high) clock mode, with the desired peripherals

Checking the exact power consumption (including the needed peripherals, as they can make a big difference) from the data sheet, reading and evaluating both typical and maximum figures is the way to go. Using generic (\$\mu\$A/MHz) figures will probably get you only a general answer.

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  • \$\begingroup\$ thanks for ur reply.power consumption can be calculated by the parameters u have suggested.but, how to compare w.r.t performance as each MCU has their own way of representing the speed and performance like uA/Mhz and MIPS and DMIPS. some MCU's instructions are executed in one cycle and others take multiple cycles. also 16bit vs 32bit \$\endgroup\$ – user32693 Nov 15 '13 at 6:25
  • \$\begingroup\$ @user32693: Exactly. Therefore, to make a sensible comparison, you have to normalize the figures. In what way to do it? By fixing the task to be done by the MCU (your particular requirements), and using parameters (eg. clock speed, peripherals enabled) that fulfills exactly these requirements. Deciding what clock speed is "enough" for your particular needs, is something nobody will do for you. Calculating based on MIPS and things like that, will give you a very rough estimate only. \$\endgroup\$ – Laszlo Valko Nov 15 '13 at 7:00

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