Tech Note 080 - ESP32/ESP8266 Data Logging Webserver

hello I'm Dave welcome to my technical notes channel in tech note 80 I'm going to demonstrate an ESP 32 data logging web server let's begin by looking at the data logger itself it's an M H - E T live ESP 32 board there with an SH T 30 temperature humidity sensor plugged in or I could use a bmp180 or a 280 or a d-18 B 20 just the temperature only that one or a DHT 11 or 22 and I like the MHT board because it's a we mas d one sort of upgrade you can use all of your existing shields you could have you course use an ordinary SP 32 board and use ad Pont cable to connect in this example there BM e 680 here's the unit running and I'm just demonstrating that it's currently set to auto scale and it shows 72 readings across the screen you can change from temperature humidity temperature dew point to the dial view of current temperature current humidity back to temperature humidity the logging interval can be varied so you can go up or down in terms of logging interval and the time to total time recorded across the screen there is as you do that that auto scale function can be turned on and off so ordinarily it's set to the default of 30 and minus 10 which can of course be adjusted Auto refresh how many times does the screen auto refresh itself every minute or every hour or five seconds as a help screen there's a setup section so you can set the minimum and maximum values for the graph the login interval and auto scale on and off and auto update or and off you can see the size of the log 2833 readings you can actually view the log now I'm going to scroll down now there's a lot of data there nearly three thousand readings and you can see the time interval between readings is nicely incremented in accord with its log in interval if power is lost it recovers the data and carries on the log in from the last reading there I'm just highlighting to show the uniform log in interval and here I'm showing a discontinuity in the date/time to show that it was probably closed down shut down and I restarted it the next day and it carried on this is if you wanted to copy all the data out to excel you can select the data and then paste it into Excel you can erase the log but you can't do it unless you erase it twice so there's a bit of a safeguard to stop inadvertent erasing and if you go back to temperature humidity that resets that flag fill erasing this diagram depicts the data logger with this different sensor types the ability to graph and set up its scales and functions and just to recap that it saves all the data to its flash memory so it can store a lot of data this is the wiring diagram for a Bosch or sense Syrian sensor is actually the i2c bus so reasonably straightforward to wire up this is wiring diagram for the sh 11 or 22 or dht11 dht22 using 1-wire bus so supply ground and data this diagram depicts the use of the mheg live the SP 32 board and its ability because it's we must D 1 like to accept the existing we must D 1 shields so it's very flexible in terms of functions the first thing the software does when it starts is if there isn't a flash storage file available it creates one so that's useful for new boards it reads the sensor and records values to the flash storage in accordance with the data log in interval set in the event of power loss or restart it recovers all the data from the flash storage and gives contiguous continuous recording ability store data can be viewed and copied for external use so you can view the log file and then copy out and into Excel where you can enhance the graphics and graphing and analyze the data data logging recording intervals can be vary from 15 seconds the minimum up to many hours per reading you can graph the last 72 points of data so the base the time base will be a function of your recording interval the the duration is a limitation of Google charts such as as long as I can make it there's a user setup screen where you can erase the data file change all the settings and change the scales change the auto refresh function you can switch the auto scale of the graph on or off you can switch the auto screen refresh on or off so if your data changes it will automatically refresh the graph for you and as usual with all of my videos and tech notes there will be software available on github g6 echo Julia Delta initially only the ESP 32 version and for the sh t 30 31 35 but I'll add more versions as required I hope you found this technical note interesting and useful

Channel: G6EJD - David

Views: 60,644

Keywords: ESP32, Webserver, Data Logging, Data Logger, sht30, graph, flash storage

Id: lH6Qiyb10v8

Length: 6min 56sec (416 seconds)

Published: Fri Jan 05 2018