UART Problem missing characters at 115200

Altera_Forum · ‎05-04-2005

Quartus 4.2 and NIOS 1.1

I want to make ymodem download, so I want use 115200 baud,

blocksize is 1026 byte.

I copied altera_avalon_uart.h and altera_avalon_uart.c in the syslib

directory and changed the uart buffersize:

# define ALT_AVALON_UART_BUF_LEN (2048)

I use Cyclone Dev. Board and standard design, so hardware should be ok.

I made a small testprogram and a loop at Tx-Rx.

I set stdout,stderr to lcd,stdin=null.

I get different results if I make my testoutputs to jtag uart or lcd.

case 1:

- tx testoutput to jtag

- rx testoutput to lcd

result: always read back 1023 characters, instead of 1024

errorcount=no of packets

sometimes after some time I get

"nios2-terminal: exiting due to I/O error communicating with target"

after this error uart1 receives correct packets with 1024 byte

case 2:

- tx testoutput to jtag

- rx testoutput to jtag

result: about 25% of the packets wrong, (only 1023 byte)

case 3:

- tx testoutput to lcd

- rx testoutput to lcd

result: about 100% of the packets are ok (1024 byte)

the critical is the tx testoutput, because in this time the

uart1 transmit and receive interrupts are running.

on my custom board I also loose characters, even I don't us

the jtag uart.

please, can someone verify the program and test results,

what's wrong ???

thanks

...# include <stdio.h># include <stdlib.h># include <time.h># include <alt_types.h># include <unistd.h># include <fcntl.h># include <sys/alt_alarm.h>

# define BYTE alt_u8# define WORD alt_u16# define DWORD alt_u32

# define UART0_RXBUFFERSIZE 2048

int uart0_rxcount;

char uart0_rxbuffer[UART0_RXBUFFERSIZE];

char uart0_txbuffer[UART0_RXBUFFERSIZE];

FILE *jtfp;

int fd0_nonblocked; // FILEDESCRIPTOR RETURNED BY OPEN

FILE * fp0_nonblocked; // FILE pointer returned by fdopen

int fd0_blocked; // FILEDESCRIPTOR RETURNED BY OPEN

FILE * fp0_blocked; // FILE pointer returned by fdopen

int com_fill_testbuffer(char *buffer,int count);

char hextoa(BYTE val);

void lcd_gotoxy(int x,int y);

int main() {

int packetcount=0;

int txcount;

int res;

int packeterror=0;

jtfp = fopen ("/dev/jtag_uart","w");

if(jtfp) {

fprintf(jtfp,"JTAG UART OPEN FOR DEBUG\n");

}

// BAUDRATE IS 115200,8,N,1

fd0_nonblocked = open("/dev/uart1",O_RDWR | O_NONBLOCK | O_NOCTTY);

fp0_nonblocked=fdopen(fd0_nonblocked,"rw+");

fd0_blocked = open("/dev/uart1",O_RDWR | O_NOCTTY);

fp0_blocked=fdopen(fd0_blocked,"rw+");

// txcount = 512;

txcount = 1024;

// dummy read

uart0_rxcount=read(fd0_nonblocked,uart0_rxbuffer,UART0_RXBUFFERSIZE);

while(1) {

com_fill_testbuffer(uart0_txbuffer,txcount);

res=write(fd0_nonblocked,uart0_txbuffer,txcount);

// TX TESTOUTPUT TO JTAG-UART

// fprintf(jtfp,"%04d UART1:TX:%d: \r\n",packetcount,res);

// TX TESTOUTPUT TO LCD

lcd_gotoxy(1,1);

printf("TX:%04d",res);

usleep(500000); // wait to complete trannsmit and receive

uart0_rxcount=read(fd0_nonblocked,uart0_rxbuffer,UART0_RXBUFFERSIZE);

if(uart0_rxcount!=txcount) packeterror++;

// RX TESTOUTPUT TO JTAG UART

// fprintf(jtfp,"UART1:RX:%d: PACKETS:%d ERRORS:%d\r\n",uart0_rxcount,packetcount++,packeterror);

// RX TESTOUTPUT TO LCD

lcd_gotoxy(1,9);

printf("RX:%04d",uart0_rxcount);

lcd_gotoxy(2,1);

printf("PA:%04d ERR:%04d",packetcount++,packeterror);

}

return 0;

}

int com_fill_testbuffer(char *buffer,int count) {

int i,k;

unsigned int seed;

seed=clock();

srand(seed);

for(i=0;i<(count/2);i++) {

k=rand()&0xff;

k=i;

buffer[i<<1]=hextoa((i>>4)&0x0f);

buffer[(i<<1)+1]=hextoa(i&0x0f);

}

return 0;

}

char hextoa(BYTE val) {

char hexchar=0;

if(val<=9) hexchar='0'+val;

if(val>=0x0a && val<=0x0f) hexchar='A'+val-0x0a;

return(hexchar);

}

void lcd_gotoxy(int x,int y) {

printf("\x1b[%d;%dH",x,y);

}

...

Altera_Forum · ‎06-30-2005

the uart have a buffer of 64 bytes defualt size.

when HW syncronization is not used, if you write more then 64 chars to the buffer before the receving side reed them , chars will be lost