What's happening every 100ms?

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Re: What's happening every 100ms?

By eketjall
- Fri Nov 18, 2016 1:57 am #58285 Makes sens. The radio is of course the power hungry part here.

Did some more testing, now with a linear regulator, AMS1117.
I see the same kind ow voltage drop. ~300mV for 0.9ms every 100ms.

What are people actually powering these things with to avoid this?
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Re: What's happening every 100ms?

By eketjall
- Fri Nov 18, 2016 10:35 am #58315
rudy wrote: Although you can look at decreasing the transmitter output power and that might help a little.

Is that as easy as just calling setOutputPower(float dBm)?

While we're at it. I'have noticed that the ESP8266 seems to work (of course way out of spec) down to under 2.0V but it can't start up after reset with less than 2.3V
Is there any way to get around that with some clever undocumented tweaks?
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Re: What's happening every 100ms?

By RichardS
- Fri Nov 18, 2016 10:54 am #58319 Maybe for your one chip, like you said its not spec'd for that, so that means only a few chips could behave like you want... its risky. When manufacturers put #'s to spec's they do it in such a way that the #'s work for 99.99% of the parts they produce.

That said, the voltage dip your seeing is a result of poor design somewhere, you have a LDO that can not provide the milliamps required or bad bulk capacitance, and hence a "brown out" or voltage dip due to these factors. I saw this in a design of mine once, and after I added 47-100uF bulk cap, and used an LDO that could REALLY provide 300mA peaks, mine went away, to the point you can not see it on the scope at any setting. The LDO I had used said 250mA, but that was crap.... some cheap Chinese knockoff LDO for sure, I used a real EXAR and I am good.

SPX3819 SOT23-5 https://www.exar.com/content/document.ashx?id=22106

RichardS
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