Ethernet shield and sd card not working togather on arduino mega

Question

I am making a web-client with an Arduino mega and Ethernet Shield. I am trying to receive data from a web-server running a php script and saving that data to the SD card located in the Arduino Ethernet shield. I have separately tested to read and write to SD and to Get data from the the php script using the Ethernet. But when i tried to merge those two code into one, i found that Ethernet is unable to connect to the web-server(php Script).But the Ethernet connects fine when i remove the SD Card from its slot. During my research i found that Arduino mega has different SPI pin configuration that the uno. And the libraries are supposed to handle the SPI data-line independently. But i still tried to manually controlled the SPI bus, but it did not work. As far as i know, i am now unable to change the SPI bus using the D4 pin for SD card and D10 pin for Ethernet.

I am using native Ethernet library and SDFat library.(I Even used the native SD library but the result is the same).

#include <Ethernet.h>
#include <SPI.h>
#include <SdFat.h>
#define Ethernet_ss_pin 53
#define Sd_ss_pin 4
// On the Ethernet Shield, CS is pin 4. SdFat handles setting SS
/////////////////////////////////////////////////////////////////////////////////
////////SD Config
/////////////////////////////////////////////////////////////////////////////////
SdFat sd;
SdFile myFile;
//const int chipSelect = 4;
const char* fileName="database.txt";
/////////////////////////////////////////////////////////////////////////////////
////////Ethernet Config
/////////////////////////////////////////////////////////////////////////////////
//String server = "rfid.unisec-bd.org"; //ip Address of the server you will connect to
//The location to go to on the server
//make sure to keep HTTP/1.0 at the end, this is telling it what type of file it is
String location = "/getData.php HTTP/1.0";
// if need to change the MAC address (Very Rare)
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
////////////////////////////////////////////////////////////////////////
EthernetClient client;
char inString[3200]; // string for incoming serial data
int stringPos = 0; // string index counter
boolean startRead = false; // is reading?
void setup() {
 Serial.begin(9600);
 pinMode(53,OUTPUT);
 pinMode(4, OUTPUT);
 pinMode(10,OUTPUT);
 ChipSelect(0);
 Ethernet.begin(mac);
 String pageValue;
 pageValue=connectAndRead(); //connect to the server and read the output
 Serial.println(pageValue); //print out the findings.
 ChipSelect(1);
 // Initialize SdFat or print a detailed error message and halt
 // Use half speed like the native library.
 // change to SPI_FULL_SPEED for more performance.
 if (!sd.begin(Sd_ss_pin, SPI_HALF_SPEED)) {
 sd.initErrorHalt("Sd initialization failed");
 }else{
 Serial.println("Sd card Initialized");
 }
 ChipSelect(0);
}
void loop() {
 Serial.println("Type any character to start");
 while (Serial.read() <= 0) {}
 delay(1000); // catch Due reset problem
 ChipSelect(2);
 String pageValue = connectAndRead(); //connect to the server and read the output
 Serial.println(pageValue); //print out the findings.
 ChipSelect(1);
 writeSd(pageValue);
 readSd();
 ChipSelect(0);
}
void readSd(){
 //const char path=(const char)fileName;
 if (!myFile.open(fileName, O_READ)) {
 sd.errorHalt("file read error");
 }
 Serial.println(fileName);
 // read from the file until there's nothing else in it:
 char data;
 int c=0;
 while ((data = myFile.read()) >= 0) {
 data=char(data);
 Serial.print(data);
 //Serial.println(c);
 c++;
 }
 // close the file:
 myFile.close();
}
void writeSd(String storeData){
 // open the file for write at end like the Native SD library
 if (!myFile.open(fileName, O_RDWR | O_CREAT | O_AT_END)) {
 sd.errorHalt("opening database.txt for write failed");
 }
 // if the file opened okay, write to it:
 Serial.print("Writing to database.txt...");
 myFile.println(storeData);
 // close the file:
 myFile.close();
 Serial.println("done.");
}
String connectAndRead(){
 ///////// Pin 10,11,12,13 are used as SPI Bus of the ethernet Shield
/// MOSI- pin 11
/// MISO- pin 12
/// CLK- pin 13
/// CS for sdCard-pin 4
/// ss- pin 10
 // On the Ethernet Shield, CS is pin 4. It's set as an output by default.
 // Note that even if it's not used as the CS pin, the hardware SS pin 
 // (10 on most Arduino boards, 53 on the Mega) must be left as an output 
 // or the SD library functions will not work. 
 //digitalWrite(Sd_ss_pin,HIGH); //SD is not active
 /* USE THIS CODE FOR PROXY SERVER IN BRAC UNIVERSITY
 // if you get a connection, report back via serial:
 if (client.connect("192.168.1.5", 8080)) { // This is connecting to the proxy
 Serial.println("connected");
 // Make a HTTP request through proxy:
 client.println("GET rfid.unisec-bd.org/getData.php HTTP/1.0");
 client.println();
 }
*/
 //connect to the server
 Serial.println("connecting...");
 while(!client){;}
 //port 80 is typical of a www page
 if (client.connect("rfid.unisec-bd.org", 80)) {
 Serial.println("connected");
 client.print("GET ");
 client.println(location);
 client.println("Host: rfid.unisec-bd.org"); // SERVER ADDRESS HERE TOO
 client.println("Content-Type: application/x-www-form-urlencoded");
 client.println();
 //Connected - Read the page
 return readPage(); //go and read the output
 }else{
 return "connection failed";
 }
}
String readPage(){
 //read the page, and capture & return everything between '<' and '>'
 stringPos = 0;
 memset( &inString, 0, 3200 ); //clear inString memory
 while(true){
 if (client.available()) {
 char c = client.read();
 if (c == '!' ) { //'!' is our begining character
 startRead = true; //Ready to start reading the part 
 }else if(startRead){
 if(c != '@'){ //'@' is our ending character
 inString[stringPos] = c;
 stringPos ++;
 }else{
 //got what we need here! We can disconnect now
 startRead = false;
 client.stop();
 client.flush();
 Serial.println("disconnecting.");
 return inString;
 }
 }
 }
 }
}
void ChipSelect(int s){
 if(s=0){ //Both Device is off
 //digitalWrite(53,HIGH);
 digitalWrite(10,HIGH);
 digitalWrite(4,HIGH);
 }else if(s=1){ //Only SD is active
 //digitalWrite(53,HIGH);
 digitalWrite(10,HIGH);
 digitalWrite(4,LOW);
 }else if(s=2){ //Only Ethernet is Active
 //digitalWrite(53,HIGH);
 digitalWrite(10,LOW);
 digitalWrite(4,HIGH);
 }
 Serial.print("Ethernet SS:");
 Serial.println(digitalRead(10));
 Serial.print("SD SS:");
 Serial.println(digitalRead(4));
}

• Jaroslav Záruba: I suppose you have seen this one: electronics.stackexchange.com/a/67214/140185

Answer 1

You have to switch off and then on pin 2 (connected to Vcc on SD reader) using digitalWrite

https://stackoverflow.com/questions/41277010/how-to-connect-rc522-rfid-module-and-sd-card-adapter-to-one-arduino-board/46797716#46797716
`//HEADER FILES##################################
#include <SPI.h>
#include <MFRC522.h>
#include <SoftwareSerial.h>
#include <EEPROM.h>
#include <SD.h>
//ARDUINO MEGA
//MISO 50
//MOSI 51
//SCK 52
//ON/OFF SD CARD READER 2
//SD Card DEfinitions###########################
File root;
const int chipSelect = 4;
const int chipONOFF = 2;
//RF_ID Definitions#############################
#define SS_PIN 7
#define RST_PIN 6
MFRC522 mfrc522(SS_PIN, RST_PIN);
void setup()
{
Serial.begin(9600);
SPI.begin();
pinMode(chipONOFF,OUTPUT);
digitalWrite(chipONOFF, LOW);
tc_03_rfIDbasicTest();
digitalWrite(chipONOFF, HIGH);
tc_02_SDcardConnectTest();
digitalWrite(chipONOFF, LOW);
tc_03_rfIDbasicTest();
}
void loop()
{ }
void tc_02_SDcardConnectTest()
{
Serial.println("");
Serial.println("");
Serial.println("-----TEST 2: FUNCIONAMIENTO BASICO DE SD-----");
Serial.println("");
if (!SD.begin(chipSelect))
{
Serial.println("Falla en comunicacion, asegurate que la uSD esté insertada e intenta de nuevo");
Serial.println("FAIL");
}
else
{
Serial.println("Tarjeta uSD Detectada");
Serial.println("PASS");
root = SD.open("/");
printDirectory(root, 0);
}
}
int tc_03_rfIDbasicTest()
{
Serial.println("-----TEST 3: FUNCIONAMIENTO BASICO DE RFid-----");
mfrc522.PCD_Init(); // Init MFRC522 chip again per each write attemp
mfrc522.PCD_DumpVersionToSerial(); // Show details of PCD - MFRC522 Card Reader details
if ( ! mfrc522.PICC_IsNewCardPresent()) 
 Serial.println("Targeta fuera de alcance"); 
else
 Serial.println("Targeta dentro de alcance");
if ( ! mfrc522.PICC_ReadCardSerial()) 
 Serial.println("Falla en lectura de tarjeta"); 
else
{
 Serial.println("RFid OK :) !");
 Serial.println("PASS");
 String nuid="";
 for (byte i = 0; i < 4; i++) 
 nuid+=mfrc522.uid.uidByte[i];
 mfrc522.PICC_HaltA();
 mfrc522.PCD_StopCrypto1();
 Serial.println(nuid);
} 
}
void printDirectory(File dir, int numTabs)
{
while (true)
{
File entry = dir.openNextFile();
if (! entry)
break;
for (uint8_t i = 0; i < numTabs; i++)
{
Serial.print('\t');
}
Serial.print(entry.name());
if (entry.isDirectory())
{
Serial.println("/");
printDirectory(entry, numTabs + 1);
}
else
{
Serial.print("\t\t");
Serial.println(entry.size(), DEC);
}
entry.close();
}
}`

and this what you get on serial monitor.

`-----TEST 3: FUNCIONAMIENTO BASICO DE RFid-----
Firmware Version: 0x92 = v2.0
Targeta dentro de alcance
RFid OK :) !
PASS
215103959
-----TEST 2: FUNCIONAMIENTO BASICO DE SD-----
Tarjeta uSD Detectada
PASS
BIO/
D70A273B.DB 44
ENROLADO.DB 57
F683B22D.DB 40
A6DE1E49.DB 38
080732DC.DB 38
08D1EF01.DB 38
08267788.DB 38
XWIFI.DB 47
CP0101.DB 26
XFEC.DB 4
CP0102.DB 26
CP0201.DB 26
SYSTEM1/
WPSETT1.DAT 12
INDEXE~1 76
CP0301.DB 26
GP01.DB 33
GP02.DB 33
GP03.DB 33
GP04.DB 32
GP05.DB 32
GS06.DB 35
GS07.DB 37
GS08.DB 36
GS09.DB 36
GS10.DB 36
GE03.DB 24
GE02.DB 20
GE01.DB 23
GS11.DB 38
AP010101.DB 69
AP010102.DB 83
-----TEST 3: FUNCIONAMIENTO BASICO DE RFid-----
Firmware Version: 0x92 = v2.0
Targeta dentro de alcance
RFid OK :) !
PASS
215103959`

• Majenko: Please hablo english.
• user31481: Por favor, usa la lengua del Imperio.