Metro M4 Express Power Requirements

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Autonomous_Sailboat
 
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Metro M4 Express Power Requirements

Post by Autonomous_Sailboat »

Hello All!

I am building a system that requires a balance between solar power generated and the electricity used for navigation/control. As such, I need to identify the power (in Watts) consumed by each of the components. I know what the voltage for each component is so I then could use the component's current requirement (in Amps) to calculate consumption in Watts (Watts = Volts * Amps).

Unfortunately, I have searched many of the technical specifications available to identify either the current or power requirements for the Adafruit Metro M4 Express. I can find that kind of information for an Arduino Uno (see Page 6, Section 3.3 Power Tree, https://docs.arduino.cc/resources/datas ... asheet.pdf) and assume it is in the same 'ball park' but I would like something a little more authoritative than my SWAG.

Can you point me in the direction of the Metro M4 Express technical reference that identifies its operating power or current requirement? Many thanks.

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mikeysklar
 
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Re: Metro M4 Express Power Requirements

Post by mikeysklar »

There are some details about power for Metro M4 in the guide. Those are more maximum limits like 5v @ 500mA.

I uploaded an Arduino blink program to mine and recorded these values:
* 5.13v / 20mA / .102W

So just blinking an LED and going easy on the processor gives you a more real world number.

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Autonomous_Sailboat
 
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Re: Metro M4 Express Power Requirements

Post by Autonomous_Sailboat »

Mikeysklar:

Many thanks for the post. I'm scratching my (bald) head looking at your test results showing a current draw of 20mA versus the 'power tree' values in the Arduino document linked above. I did the simple addition and came out with 685.3mA. I strongly suspect that I am not reading the 'power tree' correctly because that seems to be an awful lot of current for a simple microcontroller.

Of the two I believe that your 20mA is the more believable. For example, the Adafruit Ultimate Logging GPS shield is cited in the documentation as requiring 35mA which is in the ballpark that your test provided.

The Adafruit Metro's processor is so much faster than an Arduino Uno's processor that I suspect that there is a significant difference in power consumption between the two. What that difference is, however, I am unsure.

Again, many thanks for the post.

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Autonomous_Sailboat
 
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Re: Metro M4 Express Power Requirements

Post by Autonomous_Sailboat »

I'm getting closer. I just found this reference that claims that an Arduino Uno requires 100 mA when operating normally at 9 Volts.
https://diyi0t.com/arduino-reduce-power-consumption/

I also found a separate reference that claims that an Arduino Due also requires 100 mA when operating normally.
https://grobotronics.com/arduino-due-a000062.html

I'm venturing a guess that the Metro M4's current draw is in the 100 mA 'ballpark.' Until someone is able to provide a better estimate I'm going to have to go with this.

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mikeysklar
 
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Re: Metro M4 Express Power Requirements

Post by mikeysklar »

100mA ball park is a reasonable guess for a chip that is doing serial communication and computation (not just blinking an LED).

Keep in mind that most power related documents are talking about maximum current scenario so you can connect appropriately sized wire gauges and PCB traces. Actual use values tend to be much lower than documented values.

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