SdFat with Mega 2560 slower than Uno???

Other Hardware Storage
1

Hello everybody,

I am just wondering about the writing performance difference between Uno and Mega 2560 with exactly the same setting of SD-Card.
I expected Mega to be faster, but Uno was writing a defined line into a *.txt with 320 Hz and Mega with 190 Hz. BTW I am using SdFat's library. SPI_FULL_SPEED was adjusted in both cases. MEGA_SOFT_SPI was set to 1 for Mega.
Has anybody an explanation and/or hint how to speed up Mega? fat16lib maybe :P? Did I maybe miss sth.?

I am thankful for all help and information.

Greetings

2

Using hardware SPI on Uno is faster than software SPI on Mega.

Connect the SD to hardware SPI pins on Mega and use hardware SPI.

Mega SPI pins are either 50, 51, 52, 53 or the ICSP connector.

See this.

3

Thx a lot fat16lib, I will try that!

4

Can you help me? I'm not able to open the SD card into Mega Arduino.

that pins you used?

5

To repeat:

Mega SPI pins are either 50, 51, 52, 53 or the ICSP connector

See SPI reference.

The communication between the microcontroller and the SD card uses SPI, which takes place on digital pins 11, 12, and 13 (on most Arduino boards) or 50, 51, and 52 (Arduino Mega). Additionally, another pin must be used to select the SD card. This can be the hardware SS pin - pin 10 (on most Arduino boards) or pin 53 (on the Mega) - or another pin specified in the call to SD.begin()

See SD Library Reference.

6

Hello!

The problem:
I try to use sdfat.h with the sdinfo example. On uno it works but on mega its not. The wireing is correct, because the sd.h cardinfo example works on my mega board. The CS pin is OK.

IDE: 1.6.8

Any idea?
Thankx.