Hello,
I don't thick that HyperTerminal is the problem.
It can be a hardware problem.
Try to find out if it is the receiving or sending of the bytes that is
the problem.
Start sending some byte (e.g. ‘e’), when starting the software. You test
the sending of bytes.
Use an oscilloscope to check if the flanks of the RS232 signal are
straight, or is there a RC-curve?
Is the time of de send-byte the same as the received-byte?
If not you wave a problem with the baud rate.
Can it be that the signal is inverted in hardware?
Is the RS232 signal between 5..12 Volt and -5..-12 Volt.?
Wat happens if you send the inverted of a ‘e’ (= 65h = 0110 0101 )
=> (1001 1010 = 9Ah)
Robert
Mindaugas Karciauskas wrote:
Hi,
I have a problem using USART in asynchronous recieve mode. I guess the
problem is very simple, but I cannot debug it anyway. Could anybody
help me to find out what's going on? Thank you in advance.
The problem:
MSP should echo a symbol. But when I send a symbol to MSP from
HyperTerminal, for example 'e' (= 65h ), the software reads the buffer
RXBUF0 and sends it back through TXBUF0. However I don't get back 65h
but D9h instead. Or if I send 6Ch I get back FBh and so on.
It is definately not the HyperTerminal which sends the wrong code,
we've checked it. And baud rates are OK too, since when I hardcode MSP
to send some definate symbol, for example the same 'e' (= 65h ), I
recieve it corectly, i.e 'e' (= 65h ).
My code actually is almost the same as the example
"fet140_uart05_09600.c". Here it is:
#include <msp430x16x.h>
#include <signal.h>
void InitPins();
int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
InitPins(); // Pins' initialization
U0CTL = SWRST; // SWRST=1
U0CTL |= CHAR; // 8-bit character
U0TCTL |= SSEL0; // UCLK = ACLK
U0BR0 = 0x03; // 32k/9600 - 3.41
U0BR1 = 0x00; //
U0MCTL = 0x4A; // Modulation
ME1 |= UTXE0 + URXE0; // Enabled USART0 TXD/RXD
U0CTL &= ~SWRST; // Initialize USART state machine SWRST=0
IE1 |= URXIE0; // Enable USART0 RX interrupt
_EINT(); // Interrupts enabled
while (1);
}
//-------------------------------------------------------------------------------
interrupt (UART0RX_VECTOR) usart0_rx (void)
{
while (!(IFG1 & UTXIFG0)); // USART0 TX buffer ready?
TXBUF0 = RXBUF0; // read and transmit a symbol
}
//-------------------------------------------------------------------------------
void InitPins()
{
...
P3SEL = 0x30; //P3.4 and P3.5 used in USART0/UART mode
P3DIR = 0xDF; //P3.5/receive data in = IN
...
}
