Flushing of tx buffer in msp430g2553

harish yadav

Other Parts Discussed in Thread: MSP430G2553

Hello,

I ma using MSP430G2553 microcontroller and trying to send hex data on uart (through rs485 to rs232 converter ) but receiving initial character as null(0x00).

Is there any command to flush the transmitter buffer since i did not get it anywhere. Please help me, I am stuck here.

Following is code of transmitting a character:

void UART_PUTCHAR(unsigned char putchar)
{
while(!(IFG2 & UCA0TXIFG));
UCA0TXBUF=putchar;
}

in main function :

UART_PUTCHAR(0x01);
                  UART_PUTCHAR(0x04);
                  UART_PUTCHAR(0x00);
                  UART_PUTCHAR(0x00);
                  UART_PUTCHAR(0x00);
                  UART_PUTCHAR(0x15);
                  UART_PUTCHAR(0x55);
                  UART_PUTCHAR(0x99);
                  UART_PUTCHAR(0xab);

                  UART_PUTCHAR(0x71);
                  UART_PUTCHAR(0xcb);
I have initialized uart correctly and transmitted ascii string successfully, only in hex data it show first byte as null. Please help me, I am stuck here.

over 9 years ago

0 Clemens Ladisch over 9 years ago

Guru 325310 points

Does the null byte replace the 0x01 byte, or is it inserted before the 0x01 byte?

0 Dennis Eichmann over 9 years ago

Guru 74080 points

Hi Harish!

There isn't a function like this. Do you mean your first 0x01 is received as 0x00 and then 0x04 works? Could you show your complete code?

Dennis

0 harish yadav over 9 years ago in reply to Dennis Eichmann

Intellectual 490 points

It shows 0x01 byte but it then does not include the last 0xcb byte. And if i transmit all these bytes in a loop then the last 2 bytes is not displayed.

0 harish yadav over 9 years ago in reply to Dennis Eichmann

Intellectual 490 points

Hello,
rs485transmit();
for (i=0;i<2;i++)
{
UART_PUTCHAR(0x01);
UART_PUTCHAR(0x04);
UART_PUTCHAR(0x00);
UART_PUTCHAR(0x0C);
UART_PUTCHAR(0x00);
UART_PUTCHAR(0x02);
UART_PUTCHAR(0xB1);
UART_PUTCHAR(0xC8);
}
rs485receive();
rx = UART_GETCHAR();
If I try to switch from transmit to receive of rs485 then it does not show last 2 bytes 0xB1 and 0xC8 instead it shows 0x00 only one time but if i do not use receive function then i transmit all bytes correctly. These are my transmit and receive function:
void rs485transmit()
{
P2OUT |=BIT0;
P2OUT |=BIT1;
}
void rs485receive()
{
P2OUT &=~BIT0;
P2OUT &=~BIT1;

}

0 Clemens Ladisch over 9 years ago in reply to harish yadav

Guru 325310 points

Writing a byte to TXBUF starts the transmission. To wait until the byte has actually been transmitted, wait for UCBUSY to clear.

0 harish yadav over 9 years ago in reply to Clemens Ladisch

Intellectual 490 points

thnax ...

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Flushing of tx buffer in msp430g2553