arduino 从串行 rs232 中读取十六进制

Question

i have problem with get read serial data from rs232 Tx RX

my code is

uint8_t cc;
char  rtx[MAX_LEN] = { 0 };
int   ii, lenn = 0;

    Serial.print("recv (HEX): ");
    Serial.println();
    while (mySerial.available())
    {
      cc = mySerial.read();
  
      if (cc < 0x10) Serial.print("0");
      Serial.print(cc, HEX);
      rtx[lenn] = cc; lenn++;
      Serial.print("");
    }
    
Serial.println();

Here i can see my outputs with out problem

output is for example

recv (HEX): 
030039094C80703470326421A5713DFE01EA6B79AE8D9DBD94F523F95340217C739BCB3B75DE1D1EF09CF03D2F916AB390E92136074A41BBA4E95ACB

the problem i want to println rtx from out the while

for example i have used this code

char  buffer[MAX_LEN] = { 0 };
sprintf(buffer, "%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",rtx[0],rtx[1],rtx[2],rtx[3],rtx[4],rtx[5],rtx[6],rtx[7],rtx[8],rtx[9],rtx[10],rtx[11],rtx[12],rtx[13],rtx[14],rtx[15],rtx[16],rtx[17],rtx[18],rtx[19],rtx[20]);
Serial.println(buffer); 

it give only limited data with wrong

i got this

0300FF39094FFFC807034FFF70326421A571

the problem is add FFF in out and i can't get all rtx[21],rtx[22],rtx[23],rtx[23],rtx[24]......

Answer 1

Your buffer needs to be twice as large plus a trailing zero byte:

uint8_t buffer[MAX_LEN*2 + 1] = { 0 };
sprintf(buffer, "%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",rtx[0],rtx[1],rtx[2],rtx[3],rtx[4],rtx[5],rtx[6],rtx[7],rtx[8],rtx[9],rtx[10],rtx[11],rtx[12],rtx[13],rtx[14],rtx[15],rtx[16],rtx[17],rtx[18],rtx[19],rtx[20]);
Serial.println(buffer); 

The values are stored in bytes, but to convert them to a hex string each value needs 2 bytes/chars.

The number of parameters do not match the format string (21 parameters, 20 in format string).

While reading, you have to check for MAX_LEN to avoid buffer overflow.

---

Here is some example code to read and display the buffer:

#define MAX_LEN 100

uint8_t rtx[MAX_LEN] = { 0 };

ReadData();
PrintBuffer(20);


int ReadData()
{
    int lenn = 0;

    Serial.println("recv (HEX): ");

    while (mySerial.available()) {

        if (lenn >= MAX_LEN) {
            Serial.println();
            Serial.println("Buffer overflow");
            return(-1);
        }

        uint8_t cc = mySerial.read();
        PrintHexByte(cc);
        rtx[lenn++] = cc;
    }

    Serial.println();
    return(0);
}

void PrintBuffer(int len)
{
    if (len < 0 || len > MAX_LEN)
        len = MAX_LEN;

    for (int i = 0; i < len; ++i) {
        PrintHexByte(rtx[i]);
    }

    Serial.println();
}

void PrintHexByte(uint8_t cc)
{
    if (cc < 0x10)
        Serial.print("0");

    Serial.print(cc, HEX);
}