程序求解!逐行读取SD卡中的TXT文件
本帖最后由 连菜鸟都算不上 于 2015-3-5 11:29 编辑sd模块和Mege连线都没问题，就是如题的程序遇到问题了，求救。{:soso_e183:} 别沉，求解:'( /*
SD card basic file example
This example shows how to create and destroy an SD card file
The circuit:
* SD card attached to SPI bus as follows:
** MOSI - pin 11
** MISO - pin 12
** CLK - pin 13
** CS - pin 4
created Nov 2010
by David A. Mellis
modified 9 Apr 2012
by Tom Igoe
This example code is in the public domain.
*/
#include <SD.h>
File myFile;
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
}
Serial.print("Initializing SD card...");
// 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.
pinMode(10, OUTPUT);
if (!SD.begin(4)) {
Serial.println("initialization failed!");
return;
}
Serial.println("initialization done.");
if (SD.exists("example.txt")) {
Serial.println("example.txt exists.");
}
else {
Serial.println("example.txt doesn't exist.");
}
// open a new file and immediately close it:
Serial.println("Creating example.txt...");
myFile = SD.open("example.txt", FILE_WRITE);
myFile.close();
// Check to see if the file exists:
if (SD.exists("example.txt")) {
Serial.println("example.txt exists.");
}
else {
Serial.println("example.txt doesn't exist.");
}
// delete the file:
Serial.println("Removing example.txt...");
SD.remove("example.txt");
if (SD.exists("example.txt")){
Serial.println("example.txt exists.");
}
else {
Serial.println("example.txt doesn't exist.");
}
}
void loop()
{
// nothing happens after setup finishes.
} /*
SD card read/write
This example shows how to read and write data to and from an SD card file
The circuit:
* SD card attached to SPI bus as follows:
** MOSI - pin 11
** MISO - pin 12
** CLK - pin 13
** CS - pin 4
created Nov 2010
by David A. Mellis
modified 9 Apr 2012
by Tom Igoe
This example code is in the public domain.
*/
#include <SD.h>
File myFile;
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
}
Serial.print("Initializing SD card...");
// 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.
pinMode(10, OUTPUT);
if (!SD.begin(4)) {
Serial.println("initialization failed!");
return;
}
Serial.println("initialization done.");
// open the file. note that only one file can be open at a time,
// so you have to close this one before opening another.
myFile = SD.open("test.txt", FILE_WRITE);
// if the file opened okay, write to it:
if (myFile) {
Serial.print("Writing to test.txt...");
myFile.println("testing 1, 2, 3.");
// close the file:
myFile.close();
Serial.println("done.");
} else {
// if the file didn't open, print an error:
Serial.println("error opening test.txt");
}
// re-open the file for reading:
myFile = SD.open("test.txt");
if (myFile) {
Serial.println("test.txt:");
// read from the file until there's nothing else in it:
while (myFile.available()) {
Serial.write(myFile.read());
}
// close the file:
myFile.close();
} else {
// if the file didn't open, print an error:
Serial.println("error opening test.txt");
}
}
void loop()
{
// nothing happens after setup
} 哪里遇到问题嘛? 程序贴出来看下?
大概流程是这样子的:
1. 打开这个文件
2. seek(0); 文件定位到开头
3. read()读取,有一些库还会有readStringUntil()函数的,这个更方便
4. 遇到'\r'或'\n'或'\r\n'就是换行符,那前面读的就是一行的内容
5. 跳过换行符,继续读下一行.
6.直到文件结束.
yuanhaoliang 发表于 2015-3-6 11:34 static/image/common/back.gif
哪里遇到问题嘛? 程序贴出来看下?
大概流程是这样子的:
就是程序不知道怎么写，看了你的有些启发。还有疑惑如下：:$
1.用什么程序能一个一个字节读取，读取的类型是字符还是数字或是其他类型？
2.读完一行后，这行数据会被调用,下次怎么继续读下一行,而不是从头开始？
谢谢你的帮助！ anonymouscc 发表于 2015-3-5 13:13 static/image/common/back.gif
这些demo我看过了，实际功能不是他那样的，我想逐行读取数据，不是一次性读完。
谢谢你的帮助:hug: 连菜鸟都算不上 发表于 2015-3-7 00:53 static/image/common/back.gif
这些demo我看过了，实际功能不是他那样的，我想逐行读取数据，不是一次性读完。
谢谢你的帮助
是否解决了呢，楼主，贴出来看看，遇到同样问题
本帖最后由 pybok 于 2016-7-2 16:13 编辑
read()
读取文件的一个字节(byte)。
语法
file.read()
参数
file:File类的object(由SD.open()返回)
返回
下一个字节（或字符），如无下一字节（或字符）则返回 -1。
file.seek(position) 将“光标”移到某一位置 本帖最后由 pybok 于 2016-7-2 16:14 编辑
peek()
从文件读取一个字节（byte），但并不将索引位前进。也就是说，连续调用peek()将返回相同的值，再调用read()也将返回这一值。
语法
file.peek()
参数
file：File类的object（由SD.open()返回）
返回
下一个字节（或字符），如无下一个字节（或字符）则返回 -1。
---------------------------------------------------------------------------------------
先用seek（）在文件中定位，然后用feek()读1个字节的数据，反复循环定位--读取--定位--读取。。。。。。。。。。。。。。
即可！！ if(BT.read()=='A')
{
myFile = SD.open("test.txt");
while (myFile.available())
{
BT.write(myFile.read());
}
}
else
{} */
看一下這段是否用得上，讀取SD卡test.txt資料，逐字再靠藍芽傳出
有沒有辦法，讓arduino板判斷txt裡的內容後，去執行相對應的動作?
例如:TXT讀去英文字母"A"，執行A東動作；內文是"B"的話，執行B動作
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