how to convert string to byte in arduino
String myString = "25";
byte myByte = myString.toInt();
A string could be many thousands (millions even) of bits in length.
A byte is just eight.
Note that a string and a String are quite different things
Byte len=Serial.readBytesUntil('#', (char *) buffer, 20) ;
for (byte i = len; i < 20; i++) buffer = ' ';
This code is a RFID Write Code.
I am doing removing Serial and i try to insert that point string. Ex : Hello. But i can't do that.
Help me....
Full program please. Snippets are useless.
shamal:
I am doing removing Serial and i try to insert that point string. Ex : Hello. But i can't do that.
Help me....
{
char buffer[20];
const char *input = "Hello#";
int i = 0;
while (i < 20) {
if (input[i] == '#')
break;
buffer[i] = input[i];
i++;
}
while (i < 20)
buffer[i++] = ' ';
}
Thank Your Very much.........
but i have a another problem. how can i call keypad press string to that char.
Ex
I am pressing 1236A. i am creating object string (KeyInputs). that KeyInputs has a that insert values ex(1236A).
how can i input this string to that char.
Ex
String KeyInputs=1236A;
const char *input = "Hello#";
Thank all of you........
My code is successes...
i like to thanks Mr: johnwasser, with out your help i can't complete my task.
I have anther problem. I trying read and display data in rfid tag.but i can't convert to hex to string.
this my code:
{
lcd.clear();
lcd.setCursor(0,0);
lcd.print(F("RFID Reading........"));
lcd.setCursor(0,2);
lcd.print(F("Please Wait..........."));
if ( ! mfrc522.PICC_IsNewCardPresent())return;
if ( ! mfrc522.PICC_ReadCardSerial())return;
MFRC522::PICC_Type piccType = mfrc522.PICC_GetType(mfrc522.uid.sak);
if ( piccType != MFRC522::PICC_TYPE_MIFARE_MINI && piccType != MFRC522::PICC_TYPE_MIFARE_1K && piccType != MFRC522::PICC_TYPE_MIFARE_4K)
{
lcd.clear();
lcd.setCursor(0,0);
lcd.print(F("This sample only works with MIFARE Classic cards."));
return;
}
byte sector = 1;
byte blockAddr = 4;
byte trailerBlock = 7;
MFRC522::StatusCode status;
byte buffer[18];
byte size = sizeof(buffer);
mfrc522.PICC_DumpMifareClassicSectorToSerial(&(mfrc522.uid), &key, sector);
status = (MFRC522::StatusCode) mfrc522.MIFARE_Read(blockAddr, buffer, &size);
if (status != MFRC522::STATUS_OK)
{
lcd.clear();
lcd.setCursor(0,0);
lcd.print(F("Read failed"));
lcd.setCursor(0,2);
lcd.print(mfrc522.GetStatusCodeName(status));
}
dump_byte_array(buffer, 16);
tone(2,4000, 1000);
lcd.clear();
lcd.setCursor(0,0);
lcd.print("RFID Read Successful");
Serial.println();
}
void dump_byte_array(byte buffer, byte bufferSize)
{
for (byte i = 0; i < bufferSize; i++)
{
Serial.print(buffer,HEX);*
- }*
}
I try to convert HEX to string but i can't. how can i display in lcd screen that rfid read data.
Please go back and edit your post to use code tags. See How to use this forum.
Ad while you're at it, add all your code. No snippets! And then point clearly to the problem. What happens? What do you expect? Where do you think is the problem?
And you're description is pretty vague but I think you mean in the last function? Then you don't try to convert HEX to a string. Hex is just a representation, not a type. I have no idea what MIFARE_Read() return in the array but I assume the real byte value. So you want to print the value of each byte as ASCII hex.
One error I see, you pass buffer as a pointer but you don't dereference it. You print the pointer to the screen, not the data of the pointer. Or dereference it or pass it as a reference like:
void dumpByteArray(byte buffer[], byte bufferSize){
for(byte i = 0; i < bufferSize; i++){
Serial.print(buffer[i], HEX);
}
}
shamal:
Thank Your Very much.........
but i have a another problem. how can i call keypad press string to that char.
Ex
I am pressing 1236A. i am creating object string (KeyInputs). that KeyInputs has a that insert values ex(1236A).
how can i input this string to that char.
Install the Keypad library and look at the examples. In loop(), look for new key presses. If a key is pressed, act on it: If it is 0-9 or A-D, add it to your buffer. If it is '*' or '#', do what you want, like clear the buffer or use the accumulated data.