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FieldsOfFire

Delayed start MSP430FR5969

7 posts in this topic

Hi,

I'm interested in energy harvesting applications with the FR5969. I've noticed there's quite a delay before the code runs, probably 500mS or more. This is just testing with a simple piece of code that turns on the LED. Launchpad supplied direct from a power supply and all jumpers removed. Is there some boot-up routine or something going on that is automatically programmed that I'm not aware of, or something else? Obviously this is quite a significant delay for these type of applications, as all the energy is being exhausted in starting the thing up. Any ideas/experiences would be great. I'm using Energia 17 and MSP430FR5969 Launchpad.

Cheers.

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Are you using Energia? If yes, then there is indeed a delay. This is due to the startup code figuring out what clock source to use for low power modes.

Details can be found in enableXtal() in wiring.c.

Robert

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Thanks for the reply Robert. Yes I'm using Energia. I'll look at what you suggested but can this delay be overcome?

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Yes, comment out enableXtal() in wiring.c. This will however have impact on power consumption. Given that you know you have an external crystal you could modify the code to not do the detection phase. However, this is something that I will not be able to guide you in at this moment since I am heads down with other Energia tasks.

Robert

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I'm guessing then I define the clock freq etc in the main code? This is all rather new to me but thanks for the response Robert I'll see what I can do, or tear more hair out.

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"...or tear more hair out..."

May i be so bold as to suggest not using Energia in this case?

For true micropower applications, total control of all aspects of the device's operation is essential. Having a framework doing stuff you don't know about in the background is not helpful when calculating the energy budget or predicting performance.

I'm doing an FR5969 IoT project at the moment and it's coded from scratch. By careful design and fine tuning I've managed to get the power consumption so low that it'll run off a CR2032 for at least a year - every little bit of the code is tuned - I couldn't do that if there was a 3rd party framework behind it. EnergyTrace++, LPM modes and interrupts are your friends.

Energy harvesting is next up.

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Thanks for your reply nickds1.....great advice and this is exactly what I've done. I'm now using CCS and its various tools, gaining a better understanding of the microcontroller and its low power features. Bit of a steep learning curve but I'll get there.

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