[SOLVED] Having problems with history graph widget. Where to look for help?

I’m using the latest Blynk library from Sparkfun with their Blynk board and the IOS app. I’m using their standard firmware for the temperature/humidity sensor monitoring. It writes the temp to V5 and humidity to V7 in response to Blynk server requests. The documented way to run this is to use two value display widgets. That works. If I try to use a history graph widget instead, it doesn’t seem to advance. I tried using a history graph widget on V5 and V7 as well as two value display widgets on V5 and V7. The values are displayed as expected, but the history graph widget still doesn’t advance. Any suggestions? Pointers to examples of this sort of thing (using both a value widget and one channel of history graph widget with the same virtual value)?

Hello. I think I know where confusion comes from. History graph by itself doesn’t do anything. It just shows data. But in order to have this data you have to either use widget with frequency reading or use Blynk.virtualWrite on hardware side.

Thank you Dmitriy. I finally found the description in the documentation that talks about the granularity of the history graph. I had been expecting data points to show up over maybe 30 seconds which won’t happen with the 1 day scale. It would help to have a bit more documentation on the behavior of the history graph widget. For example, does the server simply echo the data to the app? What happens when the app is off-line?

Yes if we are talking about all widgets except history graph.

Nothing. All data send via Blynk.virtualWrite is still processed via server and stored. Only frequency reading widgets stop working.

Regarding history graph - it is stores average value based on granularity. In case you sent value 11 and 13 within 1 minute on graph you’ll see point 12 for that minute on 1h/6h graphs.


Is there a way to increase data granularity for one day on the history graph instead of averaging, or a better way to look at previous 6 hour intervals in a more detail without having to download data and graph in excel? I’m imagining a scrolling graph with arrows to move back and forward in time.

Thanks, I appreciate your work.

This is a older post. Please create a new post if you wish to discuss options or make suggestions. Thank you.

Also, Local Server may be what you will require. As per >documents<…

As Blynk Cloud is free to use we have a limit on how many data you can store. At the moment Blynk Cloud accepts 1 message per minute per pin. In case you send your data more frequently your values will be averaged.

Further dialogue in new post.