Simple wait-function for delaying the start-up of nRF52832

[Michael01101]

Hello,

Our Project

at the moment we are developing an application with a BMD-350, which contains a nRF52832 chip.

The BMD-350 is on a custom PCB with another microcontroller. The PCB ist powered with two small zinc-air batteries.

We developed our software for the BMD-350 that it fits the total current consumption requirement.

Our Problem

Our problem is that our total current draw is too high when both microcontrollers start up at the same time. (when they get power).

Our Idea

Our idea is to delay the start-up of the BMD-350 by a few seconds.

So our question is:

Is there a simple wait-function or something like that for delaying the start-up of the nRF52832?

Thank you very much in advance.

Best regards,

Michael

[awneil]

Maybe just some extra capacitance on the supply could help ... ?

You can't do it in the nRF52 software - because that would require the nRF52 to be already started up!

Make one of your microcontrollers the Master, and have it start the other when appropriate.

[Michael01101]

Hello awneil,

thank you very much for you reply.

Unfortunately extra capacitance does not help. 

We did some testing and we figured out, that we have to delay the nRF52 start-up by about 5 seconds, because of the used zinc-air batteries. Then all works fine.

Maybe it would be enough to execute our initializations in our main() function with a delay of 5 seconds. 

In this case the nRF52 will be still startet up, but this would lower the current consumption in the first 5 seconds significantly.

Is there a simple wait-function to implement that properly?

Thank you very much in advance.

Best regards,

Michael

[run_ar]

Hi,

If you can live with having the CPU running current consumption for a short time on boot, you could potentially just start a 5 second timer (Timer library) then go to sleep until the timer triggers, before you continue and start radio activity. See Sleep for current consumption:

ION_RAMOFF_RTC

System ON, no RAM retention, wake on RTC (running from LFRC clock)

1.50

µA

[Michael01101]

Hi run_ar,

thank you very much for your reply. 

I implemented a app_timer, which does exactly what you mentioned. It looks like my problem is solved. But I will do some further testing.

Best regards,

Michael