reading a string from uart of cortex-m3

[raghavkmr]

Hi ,
I am trying to read string from uart into cortex-m3,I can read numbers but how to go with string
below is my code to read number

int scannumber()
    {
    	uint8_t rxbuff,x[8]={0},i=0;//[8];
    	mss_uart_instance_t * this_uart = &g_mss_uart1;
    	int num;
    	while(i<8)
    	{
    	UART_Polled_Rx( &g_mss_uart1, &rxbuff, sizeof(rxbuff) );

    	if(rxbuff == '\r')
    	    	{
    	    		rxbuff= this_uart->hw_reg->RBR;
    	    		rxbuff= this_uart->hw_reg->RBR;
    	    		break;
    	    	}
    	    	else
    	    		x[i++]=rxbuff;
    	    	}
    	num = atoi(x);
    	return num;
    }

 

[Easyrider83]

Why do you using polling method? First, you should get a string. Then parse it.
When you using old crap microcontrollers like a PIC or AVR, you can use interrupt to receive data from host. But ARM gives you posibility to use FIFO and DMA.

 

[raghavkmr]

Why do you using polling method? First, you should get a string. Then parse it.
When you using old crap microcontrollers like a PIC or AVR, you can use interrupt to receive data from host. But ARM gives you posibility to use FIFO and DMA.

its polling and cortex-m3 uses fifo to do this

 

[paulfjujo]

hello,

sorry, i only now PIC MCU, not CORTEX
but,

int scannumber()
    {
        uint8_t rxbuff,x[8]={0},i=0;//[8];
        mss_uart_instance_t * this_uart = &g_mss_uart1;
        int num;
        while(i<8)
        {
        UART_Polled_Rx( &g_mss_uart1, &rxbuff, sizeof(rxbuff) );

        if(rxbuff == '\r')
                {
                   [B]x[i]=0;   // add here string terminator [/B]
                       rxbuff= this_uart->hw_reg->RBR;    // i don't now the purpose of this ????
                    rxbuff= this_uart->hw_reg->RBR;    // i don't now the purpose of this ????
                    break;
                }
                else
                    x[i++]=rxbuff;
                }
        num = atoi(x);
        return num;
    }

string length for unsigned integer 16bits is 6 .. not 8 "65536" 5 chars + zero

 

[FvM]

Apart from all detail points what might be coded differently, the function is already reading a string x which is converted to integer number. So what's your exact problem?

To return a string from a function, you would usually supply a pointer to char array that receives the string along with a maximal number of characters. Missing length check is a serious flaw of the shown code, you can easily crash the application by typing many characters without carriage return.