countrypaul:
One of the main limitations in how fast you write to an SD card is the way the code is structured. If, for example, you open and close the file after every few I/O operations then that will severely limit the performance (we keep seeing examples like that). Try posting up the code you are using (follow the forum guidelines and post it in a code block using </> from the menu for example).
#include "FS.h"
#include "SD.h"
#include "SPI.h"
void listDir(fs::FS &fs, const char * dirname, uint8_t levels){
Serial.printf("Listing directory: %s\n", dirname);
File root = fs.open(dirname);
if(!root){
Serial.println("Failed to open directory");
return;
}
if(!root.isDirectory()){
Serial.println("Not a directory");
return;
}
File file = root.openNextFile();
while(file){
if(file.isDirectory()){
Serial.print(" DIR : ");
Serial.println(file.name());
if(levels){
listDir(fs, file.name(), levels -1);
}
} else {
Serial.print(" FILE: ");
Serial.print(file.name());
Serial.print(" SIZE: ");
Serial.println(file.size());
}
file = root.openNextFile();
}
}
void createDir(fs::FS &fs, const char * path){
Serial.printf("Creating Dir: %s\n", path);
if(fs.mkdir(path)){
Serial.println("Dir created");
} else {
Serial.println("mkdir failed");
}
}
void removeDir(fs::FS &fs, const char * path){
Serial.printf("Removing Dir: %s\n", path);
if(fs.rmdir(path)){
Serial.println("Dir removed");
} else {
Serial.println("rmdir failed");
}
}
void readFile(fs::FS &fs, const char * path){
Serial.printf("Reading file: %s\n", path);
File file = fs.open(path);
if(!file){
Serial.println("Failed to open file for reading");
return;
}
Serial.print("Read from file: ");
while(file.available()){
Serial.write(file.read());
}
file.close();
}
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();
}
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();
}
void renameFile(fs::FS &fs, const char * path1, const char * path2){
Serial.printf("Renaming file %s to %s\n", path1, path2);
if (fs.rename(path1, path2)) {
Serial.println("File renamed");
} else {
Serial.println("Rename failed");
}
}
void deleteFile(fs::FS &fs, const char * path){
Serial.printf("Deleting file: %s\n", path);
if(fs.remove(path)){
Serial.println("File deleted");
} else {
Serial.println("Delete failed");
}
}
void testFileIO(fs::FS &fs, const char * path){
File file = fs.open(path);
static uint8_t buf[512];
size_t len = 0;
uint32_t start = millis();
uint32_t end = start;
if(file){
len = file.size();
size_t flen = len;
start = millis();
while(len){
size_t toRead = len;
if(toRead > 512){
toRead = 512;
}
file.read(buf, toRead);
len -= toRead;
}
end = millis() - start;
Serial.printf("%u bytes read for %u ms\n", flen, end);
file.close();
} else {
Serial.println("Failed to open file for reading");
}
file = fs.open(path, FILE_WRITE);
if(!file){
Serial.println("Failed to open file for writing");
return;
}
size_t i;
start = millis();
for(i=0; i<2048; i++){
file.write(buf, 512);
}
end = millis() - start;
Serial.printf("%u bytes written for %u ms\n", 2048 * 512, end);
file.close();
}
void setup(){
Serial.begin(115200);
if(!SD.begin()){
Serial.println("Card Mount Failed");
return;
}
uint8_t cardType = SD.cardType();
if(cardType == CARD_NONE){
Serial.println("No SD card attached");
return;
}
Serial.print("SD Card Type: ");
if(cardType == CARD_MMC){
Serial.println("MMC");
} else if(cardType == CARD_SD){
Serial.println("SDSC");
} else if(cardType == CARD_SDHC){
Serial.println("SDHC");
} else {
Serial.println("UNKNOWN");
}
uint64_t cardSize = SD.cardSize() / (1024 * 1024);
Serial.printf("SD Card Size: %lluMB\n", cardSize);
listDir(SD, "/", 0);
createDir(SD, "/mydir");
listDir(SD, "/", 0);
removeDir(SD, "/mydir");
listDir(SD, "/", 2);
writeFile(SD, "/hello.txt", "Hello ");
appendFile(SD, "/hello.txt", "World!\n");
readFile(SD, "/hello.txt");
deleteFile(SD, "/foo.txt");
renameFile(SD, "/hello.txt", "/foo.txt");
readFile(SD, "/foo.txt");
testFileIO(SD, "/test.txt");
Serial.printf("Total space: %lluMB\n", SD.totalBytes() / (1024 * 1024));
Serial.printf("Used space: %lluMB\n", SD.usedBytes() / (1024 * 1024));
}
void loop(){
}
Hey countrypaul, thanks for your response. I am using the default SD code for the ESP32, I understand your concern about opening and closing files while writing, however in the "testFileIO" function, it tests the read/write speeds uninterrupted with open and close file.