Speeding up SD card writes #1117
Description
Hardware:
Board: ESP32 Dev module
Core Installation/update date: 2/13/2018
IDE name: Arduino ID
Flash Frequency: 40Mhz
Upload Speed: ?115200?
Description:
I am trying to figure out how to speed up my SD card writes. I don't really care about the file structure of the SD card, and only want to write a lot of data to an SD card. I was hoping to get at least 1 MB/s of writing but I seem to be getting significantly lower than that no matter what I try I cant get much better than .25 MB/s.
I am not sure if this is a hardware issue, or something that I can fix with software, or if this is just the max speed I can expect.
I am using a micro sd card with an adapter like this:
I have tried the SD_MMC but haven't been able to get it to work.
Sketch:
#include <SD.h>
#define PIN_NUM_MISO 2
#define PIN_NUM_MOSI 15
#define PIN_NUM_CLK 14
#define PIN_NUM_CS 13
void setup() {
Serial.begin(9600);
delay(3000);
auto SPI = SPIClass();
SPI.begin(PIN_NUM_CLK, PIN_NUM_MISO, PIN_NUM_MOSI, PIN_NUM_CS);
auto speed = 4000000;
if(!SD.begin(PIN_NUM_CS, SPI, speed))
{
Serial.println("NOT INIT");
return;
}
testFileIO( "/test.txt", 512, 1);
testFileIO( "/test.txt", 1024, 1);
testFileIO( "/test.txt", 2046, 1);
testFileIO("/test.txt", 512, 10);
testFileIO("/test.txt", 1024, 10);
testFileIO("/test.txt", 2046, 10);
}
void loop() {
}
void testFileIO(const char * path, uint32_t buffSize, uint32_t numMB) {
//File file = fs.open(path, FILE_WRITE);
File file = SD.open(path, "w");
size_t i;
auto start = millis();
uint8_t * buff = new uint8_t[buffSize];
auto numToWrite = (numMB * 1024 * 1024) / buffSize;
for (i = 0; i<numToWrite; i++) {
//file.write(buf, buffSize);
file.write(buff, buffSize);
yield();
}
auto end = millis() - start;
double seconds = end / 1000;
if (seconds < 0)
{
seconds = 1;
}
double MBS = numMB / seconds;
Serial.printf("%d: MB per Second: %6g :", end, MBS);
Serial.printf("Seconds per MB: %6g: numMB %d buffSize %d\n", 1 / MBS, numMB, buffSize);
file.close();
delete[] buff;
}I get:
5004: MB per Second: 0.2 :Seconds per MB: 5: numMB 1 buffSize 512
4330: MB per Second: 0.25 :Seconds per MB: 4: numMB 1 buffSize 1024
4812: MB per Second: 0.25 :Seconds per MB: 4: numMB 1 buffSize 2046
46069: MB per Second: 0.217391 :Seconds per MB: 4.6: numMB 10 buffSize 512
45727: MB per Second: 0.222222 :Seconds per MB: 4.5: numMB 10 buffSize 1024
45967: MB per Second: 0.222222 :Seconds per MB: 4.5: numMB 10 buffSize 2046