New answers tagged esp32
1
The FILE_WRITE in SD library is 'append' (for historical reasons)
#define FILE_WRITE (O_READ | O_WRITE | O_CREAT | O_APPEND)
so use
File file = SD.open(filename, O_WRITE);
0
SD.seek() is the API you're looking for. It allow you to position the read/write pointer within a file. In standard C++ the fseek() API is used.
0
http.getString() creates a temporary Arduino String object and fills text into dynamic memory on the heap. Calling the method .toCharArraycopies this text to a char array, wherever you defined it.
Immediately after that, the temporary String gets out of scope and the text on the heap is deleted again.
2
The return value of getString allocates and the deletes a char array in heap for a temporary String object.
For ESP8266HTTPClient and ESP32 HTTPClient library you can use writeToStream or getStream()to read the response without using String class with getString(), where stream is WiFiClient& stream = client.getStream();
getStream, returns the ...
0
This was an issue with the old Arduino IDE snap on Ubuntu. You can easily fix this by installing the new arduino snap:
snap install arduino
Then add your user to the dailout group:
sudo usermod -a -G dialout $USER
After this, reboot your device and open Arduino IDE.
Installing additional libraries
The Arduino IDE snap runs inside of a sandbox for ...
3
I fully agree with Edgar Bonet.
My opinion is keeping a 'matrix' is better, or actually one array (of structs), where each array elements stores all information for one measurement (which is stored inside one struct). This has some benefits:
Data of one measurement is consecutive in memory, so you can easily transfer it (to some external memory or sending ...
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