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ATMega328 internal resonator for MySensors sensor?

6 years 6 months ago #1181 by mrbwa1

PaulRB wrote: I wondered if the internal oscillator, being less stable than an external crystal, was leading to inaccurate timing of the serial data, causing apparently corrupt data to be received or transmitted to the ftdi chip. I'll google that theory.


The Internal Oscillator could possible cause timing issues. I haven't tried the full MySensors sketch upload. I set up some blink sketches with short timings and let them run for a while to check for instability. I had one that seemed to have a weird blip, but then worked fine. Every other test worked fine for extended run times. I have not encountered any errors uploading simple sketches.

I will test with the full mysensors sketch when I have a moment to wire something up for testing.

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6 years 6 months ago #1182 by wergeld
I have found no issues uploading full sketches. But, I did see on the gammon site that you can use an Uno to upload sketches and use it to be the external resonator "clock" for the atmega328p you are trying to program if you are getting upload issues. I used this method when I first removed my oscillator and it worked beautifully. Basically you send in a clock signal to the atmega328p from the Uno.

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6 years 6 months ago #1222 by mrbwa1
I was able to test uploading a full sketch using one of my previously created sketches for a DHT temp/humidity sensor through the FTDI module at 3.3V to power the NRF24L01 radio. I did get a sync error the first time I tried to upload, however a second upload worked fin. It's possible I have loose wiring on the first attempt, however, it seemed that the sketch uploaded as the tx/rx lights stopped blinking, so it's like the board didn't reset right to complete the upload (again, perhaps loose wiring).

I have a few 8mhz ceramic resonators, so it would be easy to throw one in if I run into upload issues. I may also look up the board definition and slow down the serial rate as a precaution too. It's not like a few extra seconds spent uploading a sketch is a big deal.

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6 years 6 months ago #1230 by EasyIoT
I have no problems programming Arduino running on 1Mhz internal resonator. Use boards definition from this site:
iot-playground.com/2-uncategorised/9-arduino-low-power-sensor

When you use serial port for debugging use max 9600bps.

Just yesterday I've finished my universal custom low power board:
Attachments:

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6 years 6 months ago #1242 by cdj
Wow, do you sell it?
Please can you answer to post iot-playground.com/forum/mysensors-drive...tup-and-other-issues ? i don't really know what can i do to solve this....
Thanks
Dario

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6 years 3 months ago #1887 by msuzuki777
So as far as I know, there is no difference between the AtMega328 dip and the SMD one on the Pro Mini. I built some battery operated temperature sensors with nrf24L01s using the 28pin dip. I used an 8MHz oscillator instead of using the internal oscillator.
www.instructables.com/id/LOG-Wireless-Te...4/Power-Consumption/
The AtMega needs to have ProMini 8MHz bootload.
But how I save power was using this software:
code.google.com/p/narcoleptic/
to put the AtMega to sleep mostly for most of the time. Another trick I used was using an 18650 battery without a regulator. I dropped the voltage slightly for the nrf24L01 with a diode but everything else works down to about 3Vdc.
Fully charged 18650s are 4.2Vdc

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