How to run the internal RTC on the ESP32 without internet access?

I built a 4-temperature logger which creates a CSV file on an internal partition in flash for downloading via the web, the chip works in AP mode and has a small configuration via the web. It is also possible to view the graph via www and google script, I also made graphs via Ajax. Unfortunately the graph only works on the phone because the script loads from the internet, which is about 100KB. When I upload it to the internal memory and read it
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Unfortunately I achieve about 2KB/s. Which makes the file take a minute to download. Maybe someone has some other idea?

Let's move on to the 100th issue.
I need to use an internal RTC for which I found no description in the arduino. I know it is not very accurate. I have a 32.768kHz quartz connected.
I don't have internet access, the time will be set via the web. It will be added to a CSV file to show indicatively when the measurement was.

I am writing in Arduino, ESP-IDE I have seen some elaborate example.
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Przybyłek wrote:

I need to use an internal RTC

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Wouldn't the system functions settimeofday() and gettimeofday() from the newlib library (header file <sys/time.h> ) suffice in this case? You have to set the internal RTC every time you reboot the ESP32 if you are not using NTP or an external RTC with battery backup.

But this library is standard in the arduino libraries for esp32? This is what I'm referring to.

Przybyłek wrote:

But this library is standard in the arduino libraries for esp32? That's what I mean.

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The Arduino HAL library in ESP32 is entirely based on ESP-IDF , which uses, among other things, the system library newlib . In post #2 I gave you functions for writing/reading the internal RTC on the ESP32 such that are the easiest to use in my opinion.

Functions for setting the time in the Arduino HAL for ESP32 require the availability of the NTP protocol, i.e. internet access.

In summary, programming with Arduino HAL on ESP32 also means programming with ESP-IDF.

Thanks a lot I saw something about this, but now with this IDF you have brightened me up, the RTC clock works. And could you advise something else with file uploads?

Are you referring to reading and writing to SPIFFS? From what I see in post #1 you are using the SPIFFSFS class from Arduino HAL. It's easy to use and nothing more If you want to operate faster on SPIFFS then unfortunately you have to go to the "low level" functions from IDF ( Link ) and then you can use the standard in C File I/O functions (fgets, fputs). It will be much faster.

Hmm, but will it do that much? I thought the problem was more on the client.write side and sending a single character.

Przybyłek wrote:

Hmm, but will it do that much? I thought the problem was more on the client.write side and sending a single character.

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Without posting a larger snippet of the code that is causing the problems, it is difficult to advise anything.

But after all, that's all the code in the first post. While checks if the file has finished, file.read read reads a character from the file and increments a pointer to the file and write writes a pointer to the client connected via http on clnt. This while with a 100KB file takes 50s.

What type/class is the variable file ?
What type/class does the variable clnt point to?
How are both variables initialised?