SolutionsToRealTimeClockAndDataLogging < IoT_Course

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---+ Solutions to Exercise 9: Real Time Clock and Data Logging
---++ Exercise 1:

Since connecting to the Internet through !WiFi is a very common task, we develop a module doing only this. The module can be put into the /lib directory on the ESP32 (or even better: frozen into the binary of !MicroPython) making it available also for later exercises.

Here is a program connecting to the Internet through !WiFi. You will have to modify it in order to adapt it to your !WiFi SSID and password.

%ATTACHURL%/wifi_connect_UCC.py.txt

... and this is how to access it and what it will print as answers:

<img alt="wifi_connect_print.png" height="383" src="%ATTACHURL%/wifi_connect_print.png" title="wifi_connect_print.png" width="767" />
---++ Exercise 2:

Sometimes you may not have access to !WiFi but you want to set the time nevertheless. Then the solution to exercise 2 comes in handy:

%ATTACHURL%/esp32RTC.py.txt

The exercise sheet already shows how to use the program

---++ Exercise 5: Write "Hello World!" file to the SD card

In the solution I mount the SD card (skipping the OSError EPERM emitted if the card is already mounted). I then check with uos.stat if the data directory already exists and I create it if not. Then I open the hello.txt file for writing and I write "Hello World!" onto the file. I finish writing by closing the file.

In order to be sure everything went ok I re-open the file, this time for reading. I read the content and print it before closing the file again.

<img alt="sdcardHello.png" height="169" src="%ATTACHURL%/sdcardHello.png" title="sdcardHello.png" width="459" />

I can the connect to the Internet through !WiFi and start the ftp server. This allows me to transfer the hello.txt file to the PC and print it there.

<img alt="uftpd.png" height="74" src="%ATTACHURL%/uftpd.png" title="uftpd.png" width="457" />

<img alt="ftpHello.png" height="479" src="%ATTACHURL%/ftpHello.png" title="ftpHello.png" width="904" />

Here is the script:

%ATTACHURL%/mountSD.py.txt
---++ Exercise 6: Data acquisition and logging with time stamp

This exercise is quite similar to the previous one with the exception that we write real data now. You have already seen how to read out the SHT30 using the SHT3X driver and you can easily get at the time stamp with now =<i> time.time() </i>if you have set up the correct time with _ntptime_ before.

In this case I open the file for writing in append mode and I close it again after having written a new data sample.

<img alt="sht30Readout.png" height="616" src="%ATTACHURL%/sht30Readout.png" title="sht30Readout.png" width="864" />

I recuperate the data through ftp on the PC side:

<img alt="ftpSHT30Data.png" height="637" src="%ATTACHURL%/ftpSHT30Data.png" title="ftpSHT30Data.png" width="907" />

Finally I convert the time to a humanly readable form and I compare it to the time seen in !MicroPython:

<img alt="cpythonTime.png" height="166" src="%ATTACHURL%/cpythonTime.png" title="cpythonTime.png" width="948" />

And here is the script:

%ATTACHURL%/sht30Readout.py.txt

-- %USERSIG{UliRaich - 2020-05-06}%

---++ Comments

%COMMENT%

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
png	cpythonTime.png	r2 r1	manage	30.1 K	2020-05-27 - 10:23	UliRaich
txt	dayOfWeek.py.txt	r1	manage	1.7 K	2020-05-25 - 10:29	UliRaich
txt	esp32RTC.py.txt	r2 r1	manage	4.5 K	2020-05-25 - 10:29	UliRaich
png	ftp.png	r1	manage	73.6 K	2020-05-27 - 09:46	UliRaich
png	ftpHello.png	r1	manage	80.1 K	2020-05-27 - 09:56	UliRaich
png	ftpSHT30Data.png	r1	manage	136.3 K	2020-05-27 - 10:19	UliRaich
png	micropythonTime.png	r1	manage	6.9 K	2020-05-27 - 09:46	UliRaich
txt	mountSD.py.txt	r1	manage	1.6 K	2020-05-27 - 09:44	UliRaich
png	sdcardHello.png	r1	manage	18.6 K	2020-05-27 - 09:59	UliRaich
png	sht30Readout.png	r1	manage	109.4 K	2020-05-27 - 10:19	UliRaich
txt	sht30Readout.py.txt	r1	manage	2.7 K	2020-05-27 - 09:44	UliRaich
png	uftpd.png	r1	manage	6.1 K	2020-05-27 - 09:56	UliRaich
txt	wifi_connect_UCC.py.txt	r1	manage	2.0 K	2020-05-25 - 10:29	UliRaich
png	wifi_connect_print.png	r2 r1	manage	42.2 K	2020-05-25 - 11:33	UliRaich

Topic revision: r3 - 2020-05-27 - UliRaich