now another challenge is setting the filename to the date
void getFileName() {
File close();
filename = date + ".txt";
Serial.print("File name: ");
Serial.println(filename);
}
filename is a string here above.
How to set the filename with sprintf..?
sprintf(filename1, PSTR("%d-%02d-%02d"), timeinfo.tm_year+1900, timeinfo.tm_mon+1, timeinfo.tm_mday);
here filename1 is char
%s is the format specifier I think you are looking for.
%d is the format specifier for signed decimal integers.
%s is the format specifier for a C string.
"path" is a String.
"/" and "filename" are strings
Use sprintf or simple string manipulation functions, forget Strings.
Post code, not pictures.
To run the appendFile command I need the path and the filename
appendFile(SD, "path", "dataMessage");
so I have written the following
sprintf(path, PSTR("/%s"), filename );
sprintf(filename, PSTR("%s-%02s-%02s.txt"), timeinfo.tm_year+1900, timeinfo.tm_mon+1, timeinfo.tm_mday);
But the compiler compiles and upload fine, but the terminal returns me an error.
...WiFi connected
IP address:
192.168.1.169
Contacting Time Server
Initializing SD card...Initializing SD card...
Guru Meditation Error: Core 1 panic'ed (LoadProhibited). Exception was unhandled.
Core 1 register dump:
PC : 0x4008a0c5 PS : 0x00060430 A0 : 0x8014a014 A1 : 0x3ffb2410
A2 : 0x0000076c A3 : 0x00000768 A4 : 0x000000ff A5 : 0x0000ff00
A6 : 0x00ff0000 A7 : 0xff000000 A8 : 0x00000000 A9 : 0x3ffb23e0
A10 : 0x3ffb88d4 A11 : 0x3ffb8874 A12 : 0x00000001 A13 : 0x00000000
A14 : 0x00000000 A15 : 0x00000000 SAR : 0x00000004 EXCCAUSE: 0x0000001c
EXCVADDR: 0x0000076c LBEG : 0x4008a0c5 LEND : 0x4008a0d5 LCOUNT : 0xffffffff
Backtrace:0x4008a0c2:0x3ffb24100x4014a011:0x3ffb2420 0x40147dbd:0x3ffb2730 0x400d2bd4:0x3ffb27f0 0x400d7c21:0x3ffb2820
ELF file SHA256: 0000000000000000
Rebooting...
ets Jun 8 2016 00:22:57
rst:0xc (SW_CPU_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0030,len:1412
load:0x40078000,len:13416
load:0x40080400,len:3672
entry 0x400805f8
You have a string format specifier, but no string in the parameter list.
missed that.
Now
sprintf(filename, PSTR("%d-%02d-%02d.txt"), timeinfo.tm_year+1900, timeinfo.tm_mon+1, timeinfo.tm_mday);
filename above is a combination of integer + string*(.txt)*
then what should I use below..?
sprintf(path, PSTR("/%?"), filename );
If filename is a C string, simply %s
I have used %s, but ESP is unable to create the file and returns the following
Save data: xt
Appending to file: path
Failed to open file for appending
I don't understand why
xt
I'm going to write this down one more time:
I can't see your code.
The reason for returning xt was I had set a shorter array for the path, where it couldn't fit in the file name. expanding it has solved the problem.
Now the file is getting created, but the appendFile is unable to run.
Seems I am making a mistake here
appendFile(SD, "path", "dataMessage");
here is the complete code below.
#include "FS.h"
#include "SD.h"
#include "SPI.h"
#include <time.h>
#include <WiFi.h>
int second=0;
int date = 0;
struct tm timeinfo;
char buff[50];
char filename[40];
const char* ssid = "SSID";
const char* password = "xxxx";
const char* ntpServer = "pool.ntp.org";
const long gmtOffset_sec = 19800;
const int daylightOffset_sec = 0;
String dataMessage;
String date;
char path[40];
//=========================== WRITE FUNCTION ============================//
// Write to the SD card (DON'T MODIFY THIS FUNCTION)
void writeFile(fs::FS &fs, const char * path, const char * message) {
Serial.printf("Writing file: %s\n", path);
File file = fs.open(path, FILE_WRITE);
if(!file) {
Serial.println("Failed to open file for writing");
return;
}
if(file.print(message)) {
Serial.println("File written");
} else {
Serial.println("Write failed");
}
file.close();
}
//=========================== APPEND FUNCTION ============================//
// Append data to the SD card (DON'T MODIFY THIS FUNCTION)
void appendFile(fs::FS &fs, const char * path, const char * message) {
Serial.printf("Appending to file: %s\n", path);
File file = fs.open(path, FILE_APPEND);
if(!file) {
Serial.println("Failed to open file for appending");
return;
}
if(file.print(message)) {
Serial.println("Message appended");
} else {
Serial.println("Append failed");
}
file.close();
}
//============================= LOGGING FUNCTION ================================//
void logSDCard() {
dataMessage = (buff);
Serial.print("Path: ");
Serial.println(path);
Serial.print("Save data: ");
Serial.println(dataMessage);
// appendFile(SD, path.c_str(), dataMessage.c_str());
appendFile(SD, "path", "dataMessage");
}
//================================ SETUP ================================//
void setup() {
pinMode(5, INPUT_PULLUP);
pinMode(18, INPUT_PULLUP);
pinMode(19, INPUT_PULLUP);
pinMode(23, INPUT_PULLUP);
Serial.begin(115200);
Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
Serial.println("Contacting Time Server");
configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);
Serial.print("Initializing SD card...");
// Initialize SD card
SD.begin(5);
if(!SD.begin(5)) {
Serial.println("Card Mount Failed");
return;
}
uint8_t cardType = SD.cardType();
if(cardType == CARD_NONE) {
Serial.println("No SD card attached");
return;
}
Serial.println("Initializing SD card...");
if (!SD.begin(5)) {
Serial.println("ERROR - SD card initialization failed!");
return; // init failed
}
} //End of SETUP
//================================ LOOP ================================//
void loop() {
if(!getLocalTime(&timeinfo)){
Serial.println("Failed to obtain time");
return;
}
sprintf(buff, PSTR("%d-%02d-%02d,%02d:%02d:%02d \n"),timeinfo.tm_year+1900, timeinfo.tm_mon+1, timeinfo.tm_mday, timeinfo.tm_hour, timeinfo.tm_min, timeinfo.tm_sec );
if(date != timeinfo.tm_mday){
sprintf(filename, PSTR("%d-%02d-%02d.txt"), timeinfo.tm_year+1900, timeinfo.tm_mon+1, timeinfo.tm_mday);
sprintf(path, PSTR("/%s"), filename );
date=timeinfo.tm_mday;
}
if(second != timeinfo.tm_sec){
logSDCard();
second=timeinfo.tm_sec;
}
} // End of LOOP
The return in the terminal
Appending to file: path
Failed to open file for appending
Path: /2021-06-16.txt
Save data: 2021-06-16,00:50:18
Aren't filenames 8.3?
Still got Strings?
why are you always so angry with String..?
I was making a mistake below. Was converting path and dataMessage to char
also the data message would be buff which has all the data to be written in it.
appendFile(SD, "path", "dataMessage");
Also I forgot to delete
String date;
I have to admit that you have superb way of pointing out faults.
Thank you once again for teaching me things.
Currently I have no String in the code. 
No, I have a terrible way.
I know that I don't know all the answers - but I do know some really good questions.
Very well said.. 
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