Arm Mbed OS support forum

Mbed lpc1768 Optimisation

Hello everyone, I’ve already asked questions here and it helped a lot, so here’s my new one.
Currently working on a project with mbed NXP LPC1768, and I have to minimise the needed power supply for my whole system (mbed + sensors).
As an option, my teacher proposed to optimise the mbed through “Power Control” Library by cutting the ethernet on the card (which will take the consumption from about 140 mA to 100 mA).
The problem is that I need a way to measure this current to make sure that the optimisation has been done correctly, i’ve looked on some pages but i can’t find anything convincing, any propositions to test this please ?
Thank you.

Hi Lilia, this is an interesting topic. The LPC1768 current consumption is definitely on the high side! You can do a reasonable current measurement simply by inserting a digital voltmeter on ammeter range in series with the power supply. Check that the voltage drop across the ammeter is tolerable (it will be different for different ranges). Your teacher has put you on the right track. It’s interesting to vary clock frequencies, and manipulate the PLL. You’ll find a little more in Chapter 15, Section 5, of “Fast and Effective Embedded System Design” by Toulson and Wilmshurst. Hope you get the results you need!

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Thank you very much for your answer, I’ll certainly make use of it and dig more into this.

The notebook page of the “PowerControl” library could also provide useful information.

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