解决arduino mega2560 外接SD卡模块不能读取的问题
arduino mega2560 必须接在icsp针脚上才可正确读取，接在 miso-》50 mosi-》 51 sck-》52 上面不可以读取 或者说读取不稳定吧 时好时坏。所以正确的接法是在ICSP上进行。
接法如下
icsp脚对应如下：
从1开始依次是：再看ICSP的引脚：
1--MISO
2--VCC
3--SCK
4--MOSI
5--RESET //这个脚没有用
6--GND
记得一定要把所有的除了5以外的SD卡上的脚都接上 vcc gnd必须接在icsp上
cs接在53号脚上，就一定可以正常读写了。
记得SD卡事先格式化成fat32，不管多少g的SD卡都可以！！！不要迷信什么小于2g的那是瞎扯的，注意接线正确就一定可以的！！！！！！！！！！
我也是搞了好久才找到的，累死了，希望可以帮助大家！！！！！！下面的代码直接复制进去arduino IDE 直接就可以测试了！！！
/*
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
created28 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
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 Leonardo only
}*/
// List Pin Mode
Serial.print("SS_PIN->");
Serial.println( SS_PIN );
Serial.print("MOSI_PIN->");
Serial.println( MOSI_PIN );
Serial.print("MISO_PIN->");
Serial.println( MISO_PIN );
Serial.print("SCK_PIN->");
Serial.println( SCK_PIN );
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.print("\nCard 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;
}
// print the type and size of the first FAT-type volume
uint32_t volumesize;
Serial.print("\nVolume type is FAT");
Serial.println(volume.fatType(), DEC);
Serial.println();
volumesize = volume.blocksPerCluster(); // clusters are collections of blocks
volumesize *= volume.clusterCount(); // we'll have a lot of clusters
volumesize *= 512; // SD card blocks are always 512 bytes
Serial.print("Volume size (bytes): ");
Serial.println(volumesize);
Serial.print("Volume size (Kbytes): ");
volumesize /= 1024;
Serial.println(volumesize);
Serial.print("Volume size (Mbytes): ");
volumesize /= 1024;
Serial.println(volumesize);
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) {
}
学习了 谢谢 谢谢分享
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