Best Low Power Microcontroller

[juam_r]

I am planning on working on a project for a very low power (few miliwatts), short range, low data rate (<=300 bps), very low frequency wireless communication system (<10kHz). I currently do not have defined all the details but my main constraint will be power. So the question is the following: which will be the best low power microcontroller for this project? My current options are the following:

• https://www.digikey.com/products/en?keywords=MAX32630FTHR
• https://www.microchip.com/design-centers/8-bit/pic-mcus/device-selection/pic18f-k40
• https://store.arduino.cc/usa/arduino-nano
• https://www.ti.com/store/ti/en/p/product/?p=MSP430FR2355TRHAR

Any suggestion or advice? I will try to keep you posted when I have more details! I need a microcontroller because I am supposed to transfer sensor/data information between the TRxs.

 

[nsaspook]

If a pic18 device is your choice the K42 series would be my selection if you're using C as the programming language.
https://www.microchip.com/design-centers/8-bit/pic-mcus/device-selection/pic18f-k42

 

[Nigel Goodwin]

According to specs PIC's are the lowest powered processors out there, however I can never seem to even approach their claimed figures no matter what I do. The consumption is nice and low, but no where near what they claim it should be.

 

[ronsimpson]

My low power projects used 8 pin and 6 pin u-computers. Some were PICs but almost every one that makes small computers dose low power.
-Keep the clock as slow as possable.
-Turn off any unused peripherals.
-Go to sleep, awake on event.
-Change clock speed, depending in demand. (if you can change speed in software)
-Keep the voltage low.

Read and re-read the data sheet on "low power".

 

[Pommie]

How often will the radio be used?

Mike.

 

[atferrari]

if you're using C as the programming language.

Not to derail this thread nsaspook, but what if using Assembly instead of C? Curious about that.

 

[Nigel Goodwin]

My low power projects used 8 pin and 6 pin u-computers. Some were PICs but almost every one that makes small computers dose low power.
-Keep the clock as slow as possable.
-Turn off any unused peripherals.
-Go to sleep, awake on event.
-Change clock speed, depending in demand. (if you can change speed in software)
-Keep the voltage low.

Read and re-read the data sheet on "low power".

Another important (more important?) tip is to turn off any external devices and components that you can - particularly for what the OP is wanting to do, he needs to turn off the radio module when not in use. In mine I also turn off the supply to any I2C chips, including the pull-up resistors, as those waste power as well. I also turn off the battery monitoring resistive divider, to lose that waste as well.

 

[Nigel Goodwin]

Not to derail this thread nsaspook, but what if using Assembly instead of C? Curious about that.

I suspect his only point was that the 18F series were designed and optimised for C compilers, assembly would be just as good (if not better) as far as consumption is required. The new enhanced 16F series are also 'C friendly', and the compilers produce better code than for the non-enhanced chips - but you can produce better assembler code just as well.

 

[ronsimpson]

he needs to turn off the radio module when not in use.

One project; we used real time clocks to get all the modules to synchronize. The radios were turned on once every 10 minutes. Even in the receiving mode the radio was on for only 1% of the time.

 

[juam_r]

Thanks for your advice! The radio will be used on demand. There will be a constant supply of power but this power is limited to 200mW or maybe less so I would like to minimize power consumption to make sure there is enough power available for the wireless transmission. However, sometimes I think that the power consumption of the MCU will be negligible when compared to the data PA.

 

[Nigel Goodwin]

Thanks for your advice! The radio will be used on demand. There will be a constant supply of power but this power is limited to 200mW or maybe less so I would like to minimize power consumption to make sure there is enough power available for the wireless transmission. However, sometimes I think that the power consumption of the MCU will be negligible when compared to the data PA.

Switch the power to it when it's not been used, it will waste a huge amount more than the processor, I use some little SM dual-FET's for the switching, which have a very low RDS and a high current capacity.