I have a strange problem with the SD card reader. :o
When I connect my mega to the power, then the SD card is not initialized. Only after I take the Mega briefly from the power and reconnect, the SD card is initialized.
A reset does not help, but I seem to have the card reader for a short time from the power, so that it can be initialized. If the mega is switched off for a few minutes and not connected to the power, the problem starts from the beginning.
Edit:
If the card could not be initialized, I remove the SD card and plug it in again. Thereafter, the card is properly initialized after a reset.
The behavior can be reproduced with the example sketches.
What do I have to do to ensure that the SD card is correctly initialized when the Mega is first started?
The SD card module is the only one connected to the Mega.
Here is an example sketch with the same strange behavior:
/*
SD card test
This example shows how use the utility libraries on which the'
SD library is based in order to get info about your SD card.
Very useful for testing a card when you're not sure whether its working or not.
The circuit:
SD card attached to SPI bus as follows:
** MOSI - pin 11 on Arduino Uno/Duemilanove/Diecimila
** MISO - pin 12 on Arduino Uno/Duemilanove/Diecimila
** CLK - pin 13 on Arduino Uno/Duemilanove/Diecimila
** CS - depends on your SD card shield or module.
Pin 4 used here for consistency with other Arduino examples
created 28 Mar 2011
by Limor Fried
modified 9 Apr 2012
by Tom Igoe
*/
// include the SD library:
#include <SPI.h>
#include <SD.h>
// set up variables using the SD utility library functions:
Sd2Card card;
SdVolume volume;
SdFile root;
// change this to match your SD shield or module;
// Arduino Ethernet shield: pin 4
// Adafruit SD shields and modules: pin 10
// Sparkfun SD shield: pin 8
// MKRZero SD: SDCARD_SS_PIN
const int chipSelect = 53;
void setup() {
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
Serial.print("\nInitializing SD card...");
// we'll use the initialization code from the utility libraries
// since we're just testing if the card is working!
if (!card.init(SPI_HALF_SPEED, chipSelect)) {
Serial.println("initialization failed. Things to check:");
Serial.println("* is a card inserted?");
Serial.println("* is your wiring correct?");
Serial.println("* did you change the chipSelect pin to match your shield or module?");
return;
} else {
Serial.println("Wiring is correct and a card is present.");
}
// print the type of card
Serial.println();
Serial.print("Card type: ");
switch (card.type()) {
case SD_CARD_TYPE_SD1:
Serial.println("SD1");
break;
case SD_CARD_TYPE_SD2:
Serial.println("SD2");
break;
case SD_CARD_TYPE_SDHC:
Serial.println("SDHC");
break;
default:
Serial.println("Unknown");
}
// Now we will try to open the 'volume'/'partition' - it should be FAT16 or FAT32
if (!volume.init(card)) {
Serial.println("Could not find FAT16/FAT32 partition.\nMake sure you've formatted the card");
return;
}
Serial.print("Clusters: ");
Serial.println(volume.clusterCount());
Serial.print("Blocks x Cluster: ");
Serial.println(volume.blocksPerCluster());
Serial.print("Total Blocks: ");
Serial.println(volume.blocksPerCluster() * volume.clusterCount());
Serial.println();
// print the type and size of the first FAT-type volume
uint32_t volumesize;
Serial.print("Volume type is: FAT");
Serial.println(volume.fatType(), DEC);
volumesize = volume.blocksPerCluster(); // clusters are collections of blocks
volumesize *= volume.clusterCount(); // we'll have a lot of clusters
volumesize /= 2; // SD card blocks are always 512 bytes (2 blocks are 1KB)
Serial.print("Volume size (Kb): ");
Serial.println(volumesize);
Serial.print("Volume size (Mb): ");
volumesize /= 1024;
Serial.println(volumesize);
Serial.print("Volume size (Gb): ");
Serial.println((float)volumesize / 1024.0);
Serial.println("\nFiles found on the card (name, date and size in bytes): ");
root.openRoot(volume);
// list all files in the card with date and size
root.ls(LS_R | LS_DATE | LS_SIZE);
}
void loop(void) {
}
Copy code to mega results in:
Initializing SD card...initialization failed. Things to check:
is a card inserted?
is your wiring correct?
did you change the chipSelect pin to match your shield or module?
removing and replacing card, then pressing reset on the mega:
nitializing SD card...Wiring is correct and a card is present.
Card type: SDHC
Clusters: 1931520
Blocks x Cluster: 8
Total Blocks: 15452160
Volume type is: FAT32
Volume size (Kb): 7726080
Volume size (Mb): 7545
Volume size (Gb): 7.37
this module has know problems to work with other SPI devices, but as single device it should work. how did you wire it. over a breadboard? to 50-53 or to ICSP header?
MonsterBenny:
It is directly connected via jumper wires to the mega on pins 50-53, GND and 5V.
I checked the wiring a thousand times... everything is fine.
Only on the second start or after the new plug in the SD card and a reset it works. Is not that strange?
it will be a hardware problem with the adapter or card
