How to sprintf with uint8_t array?-CodePudding

The main problem is that actually I have a uint8_t* data buffer. It an array and I only know Its size and Its pointer.

I want to sprintf the data from this pointer in a buffer like this :

void send_bin(uint8_t* binarypayload, uint8_t size, uint32_t mode)
{

    char buffer[256];
    sprintf(buffer, "AT ZF=%s,%lu\r\n", binarypayload, mode);
    HAL_UART_Transmit(&husart1, (uint8_t*)buffer, strlen((char*) buffer), 1000);
}

But on my uart I can only see the binary value on my uart:

þTÞ˜.

Where am I going wrong ?

Sorry I have forgotten to say that my datas is like :

uint8_t buffer[4] = {0x45, 0xAD, 0xEF, 0x5B};

And I want it to look like this on my uart :

AT ZF=45ADEF5B,45

but I only have access to its pointer

CodePudding user response：

You need to convert the binary data into a hexadecimal format. The easiest way, is to convert each byte individually:

void send_bin(uint8_t* binarypayload, uint8_t size, uint32_t mode)
{
    char buffer[256];
    strcpy(buffer, "AT ZF=");
    for (int i = 0; i < size; i  ) {
         sprintf(buffer   strlen(buffer), "x", binarypayload[i]);
    }
    sprintf(buffer   strlen(buffer), ",%lud\r\n", mode);
    HAL_UART_Transmit(&husart1, (uint8_t*)buffer, strlen(buffer), 1000);
}

CodePudding user response：

snprintf can convert the bytes into their hexadecimal format in a string, but it doesn't have the automatic ability to do that to an array of them. We can call it multiple times in a for loop to enable that ability though.

void send_bin(uint8_t* binarypayload, uint8_t size, uint32_t mode) {
  char buffer[256] = {};
  int offset = 0;

  int ret = snprintf(buffer   offset, sizeof(buffer) - offset,
                     "AT ZF=");
  assert(ret == 6);
  offset  = ret;

  for (int i = 0; i < size; i  ) {
    ret = snprintf(buffer   offset, sizeof(buffer) - offset;
                   "X", binarypayload[i]);
    assert(ret == 2);
    offset  = ret;
  }

  ret = snprintf(buffer   offset, sizeof(buffer) - offset,
                 "\r\n");
  assert(ret == 2);
  
  HAL_UART_Transmit(&husart1, (uint8_t*)buffer, strlen((char*) buffer), 1000);
}

CodePudding user response：

sprintf on uC for this simple task is overkill. And it will not work if you decide to use RTOS in your project.

I would:

const char digits[] = "0123456789ABCDEF";

char *dumphex(char *buff, const void *data, size_t size)
{
    char *wrk = buff;
    const uint8_t *u8data = data;

    if(buff && data)
    {
        while(size--)
        {
            *wrk   = digits[*u8data >> 4];
            *wrk   = digits[*u8data & 0x0f];
        }
        *wrk = 0;
    }
    return buff;
}

or if you do not want to use lookup string

#define GETDIGIT(x) ((x) > 9 ? ((x) - 10)   'A' : (x)   '0')

char *dumphex1(char *buff, const void *data, size_t size)
{
    char *wrk = buff;
    const uint8_t *u8data = data;

    if(buff && data)
    {
        while(size--)
        {
            *wrk   = GETDIGIT(*u8data >> 4);
            *wrk   = GETDIGIT(*u8data & 0x0f);
        }
        *wrk = 0;
    }
    return buff;
}