Hi everyone..
I have some question.
I'm using RPi rev2 and I generally write code with wiringPi library on C language.
So I write a simple serial code and checked.
Firstly I used P1 header RX and TX pins to communicate with Desktop.
When the code is working, I had some trouble on communication.
When I send a data from pc to Rpi, RPi didn't take the sending data. But when I send
quickly 30 times or 40 times send same data from pc to RPi, that's time he has began working.
and l tried another port sending and receiving data.
I used usb to communicate. And I used same code but only modify in code "/dev/ttyUSB0".
but that's time it is working very well. I could not understand why I can't receive a data from pc .
Has any idea about that???
Re: UART RX TX problem
i have the same problem.. i need to read and write whit 1200baudrate...
i have this code:
I don't know why the raspberry have this lagg...
and when it work after 50-60-...-100 charater when i send A then A then B i read A A A B.... so i have a retard....
i have this code:
Code: Select all
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdarg.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
int main()
{
int fd, retval;
unsigned char lett;
//char apriporta[5]={0x00,0x3E,0x64,0xE7,0x89};
//char rispondi_chiudi[5]={0x00,0xCC,0x64,0xE7,0x17};
//char occhio[5]={0x00,0x4F,0x64,0xE7,0x9A};
////////////////////////////////////////////////////////////////////////////////////////////
// Configurazione seriale
fd = open("/dev/ttyAMA0", O_RDWR);
if (fd < 0)
{
printf ("Non posso aprire la porta seriale: /dev/ttyAMA0\n");
}
struct termios options;
tcgetattr(fd, &options);
options.c_cflag |= CREAD; //abilito ricezione
options.c_cflag |= CSIZE + CS8; //8 caratteri
cfsetispeed(&options, B1200); //boudrate 1200
//options.c_lflag &= ~(ICANON | ECHO | ISIG); // disabilito terminatore
tcsetattr(fd, TCSANOW, &options);
tcflush(fd, TCIOFLUSH);
//
while(1)
{
retval = read(fd, &lett, 1);
printf("\nho letto: %c",lett);
//tcflush(fd, TCIOFLUSH);
}
close(fd);
printf ("\n") ;
return 0 ;
}//fine main
and when it work after 50-60-...-100 charater when i send A then A then B i read A A A B.... so i have a retard....
Re: UART RX TX problem
Post your code.
Arduino data loggers, user interface, printed circuit board designer since 2009, RPI 3B 2B 2B Zero Jessie, assembly/C/C++/java/python programmer since the 80's
Re: UART RX TX problem
liudr wrote:Post your code.
Code: Select all
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdarg.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
int main()
{
int fd, n;
//char apriporta[5]={0x00,0x3E,0x64,0xE7,0x89};
//char rispondi_chiudi[5]={0x00,0xCC,0x64,0xE7,0x17};
//char occhio[5]={0x00,0x4F,0x64,0xE7,0x9A};
////////////////////////////////////////////////////////////////////////////////////////////
// Configurazione seriale
fd = open("/dev/ttyAMA0", O_RDWR);
if (fd < 0)
{
printf ("Non posso aprire la porta seriale: /dev/ttyAMA0\n");
}
struct termios options;
tcgetattr(fd, &options);
options.c_cflag |= CREAD; //abilito ricezione
options.c_cflag |= CSIZE + CS8; //8 caratteri
cfsetispeed(&options, B2400); //boudrate 1200
//options.c_lflag &= ~(ICANON | ECHO | ISIG); // disabilito terminatore
tcsetattr(fd, TCSANOW, &options);
tcflush(fd, TCIOFLUSH);
char buf[256];
while(1)
{
n = read(fd, (void*)buf, 255);
if (n < 0) {
printf("\nRead failed");
return -1;
} else if (n == 0) printf("\nNo data on port");
else {
buf[n] = '\0';
printf("\n%i bytes read : %s", n, buf);
}
}
close(fd);
printf ("\n") ;
return 0 ;
}//fine main
Re: UART RX TX problem
The following code works. You'll need to remove all the irrelevant code.
Code: Select all
#include <stdio.h> /* Standard input/output definitions */
#include <stdlib.h> /* exit */
#include <string.h> /* String function definitions */
#include <unistd.h> /* UNIX standard function definitions */
#include <fcntl.h> /* File control definitions */
#include <errno.h> /* Error number definitions */
#include <termios.h> /* POSIX terminal control definitions */
#include <ctype.h> /* isxxx() */
/* ------------------------------------------------------------------------
cc -o 433 433.c
Usage ./433 [option] ...
-r, receiver (default)
-t, transmitter
-s BPS, bits per second, default 2400
(300, 600, 1200, 1800, 2400, 4800, 9600, 19200)
-m COUNT, test messages, default 1000
./433 -t -s4800 -m500 run as transmitter send 500 messages at 4800 bps
./433 -r -s4800 run as receiver (default), receive at 4800 bps
-------------------------------------------------------------------------- */
#define PREAMBLE 0x21
#define SYNC 0xAA
int rx = 1; /* defaults to receiver end */
int messages = 1000; /* default send 1000 test messages */
speed_t speed = B2400; /* default to 2400 bps */
struct termios orig;
int filedesc;
/* prototypes */
int openSerialPort (char * device, int bps);
void tx_message (int fd, int mlen, char * dat);
int rx_message (int fd, char * dat);
int initOpts (int argc, char *argv[]);
void tidyup(void);
int main(int argc, char *argv[])
{
int i, c;
char buf[512];
initOpts(argc, argv);
filedesc = openSerialPort("/dev/ttyAMA0", speed);
if (filedesc == -1) exit(1);
atexit(tidyup);
if (rx)
{
while(1)
{
usleep(100);
c = rx_message(filedesc, buf);
if (c > 0)
{
buf[c]=0;
printf(buf);
}
}
}
else
{
for (i=1; i<=messages; i++)
{
sprintf(buf, "message #%d\n", i);
tx_message(filedesc, strlen(buf), buf);
usleep(500); /* delay between messages */
}
}
}
void tidyup(void)
{
fflush(NULL); /* flush output */
/* important to use TCSAFLUSH, otherwise buffered messages will be lost */
tcsetattr(filedesc, TCSAFLUSH, &orig); /* restore original serial settings */
}
int openSerialPort(char * device, int bps)
{
int fd;
struct termios new;
char buf[128];
fd = open(device, O_RDWR | O_NOCTTY | O_NDELAY | O_NONBLOCK);
if (fd == -1)
{
sprintf(buf, "openSerialPort %s error", device);
perror(buf);
}
else
{
tcgetattr(fd, &orig); /* save current serial settings */
tcgetattr(fd, &new);
cfmakeraw(&new);
fprintf(stderr, "speed=%d\n", bps);
cfsetispeed(&new, bps);
cfsetospeed(&new, bps);
tcsetattr(fd, TCSANOW, &new); /* set new serial settings */
fcntl (fd, F_SETFL, O_RDWR);
}
return fd;
}
int checksum(int len, char * dat)
{
int cksm;
int i;
cksm = 0;
for (i=0; i<len; i++) cksm ^= dat[i];
return cksm;
}
void tx_message(int fd, int mlen, char * dat)
{
char buf[300];
char cksm;
int wrote;
buf[0] = SYNC; /* gives time for the receiving uart to sync */
buf[1] = SYNC; /* gives time for the receiving uart to sync */
buf[2] = PREAMBLE;
buf[3] = mlen;
memcpy(buf+4, dat, mlen);
cksm = checksum(mlen+2, buf+2);
buf[mlen+4] = cksm;
wrote = write(fd, buf, mlen+5);
if (wrote != (mlen+5)) printf("short write %d\n", wrote);
}
void printBuf(char * buf, int bufLen)
{
int i;
for (i=0; i<bufLen; i++)
{
if (isprint(buf[i])) printf("%c ", buf[i]);
else printf("%02X ", buf[i]);
}
printf("\n");
}
int rx_message(int fd, char * dat)
{
static int posBuf=0;
static char msgBuf[512];
int i, scanning, mlen, validMessage;
char cksm;
char * ptr;
validMessage = 0;
i = read(fd, msgBuf+posBuf, sizeof(msgBuf)-posBuf);
if (i>0)
{
posBuf += i;
scanning = 1;
while (scanning)
{
if (msgBuf[0] != PREAMBLE)
{
/* find message start */
ptr = memchr(msgBuf, PREAMBLE, posBuf);
if (ptr != NULL)
{
/* preamble found, discard previous junk */
i = ptr - msgBuf;
posBuf -= i;
memmove(msgBuf, ptr, posBuf);
}
else
{
/* no preamble found, discard junk */
posBuf = 0;
scanning = 0;
}
}
if (posBuf > 2)
{
/* we have enough to calculate size */
mlen = msgBuf[1];
if (posBuf > (mlen+2))
{
/* we have enough for a message */
cksm = checksum(mlen+2, msgBuf);
if (msgBuf[mlen+2] == cksm)
{
/* valid message received */
validMessage = 1;
/* copy message to callers buffer */
memmove(dat, msgBuf+2, mlen);
/* remove from receive buffer */
posBuf -= (mlen+3);
if (posBuf) memmove(msgBuf, msgBuf+mlen+3, posBuf);
scanning = 0;
}
else
{
/* corrupt message or invalid preamble.
Delete preamble and search for another
*/
msgBuf[0] = 0;
}
}
else scanning = 0;
}
else scanning = 0;
}
}
if (validMessage) return mlen; else return 0;
}
int initOpts(int argc, char *argv[])
{
int opt;
while ((opt = getopt(argc, argv, "m:rs:t")) != -1)
{
switch (opt)
{
case 'm':
opt = atoi(optarg);
if (opt>0) messages = opt;
break;
case 'r':
rx = 1;
break;
case 's':
opt = atoi(optarg);
if (opt == 300) speed = B300;
else if (opt == 600) speed = B600;
else if (opt == 1200) speed = B1200;
else if (opt == 1800) speed = B1800;
else if (opt == 2400) speed = B2400;
else if (opt == 4800) speed = B4800;
else if (opt == 9600) speed = B9600;
else if (opt == 19200) speed = B19200;
break;
case 't':
rx = 0;
break;
}
}
return 0;
}
Re: UART RX TX problem
Same problem.joan wrote:The following code works. You'll need to remove all the irrelevant code.Code: Select all
#include <stdio.h> /* Standard input/output definitions */ #include <stdlib.h> /* exit */ #include <string.h> /* String function definitions */ #include <unistd.h> /* UNIX standard function definitions */ #include <fcntl.h> /* File control definitions */ #include <errno.h> /* Error number definitions */ #include <termios.h> /* POSIX terminal control definitions */ #include <ctype.h> /* isxxx() */ /* ------------------------------------------------------------------------ cc -o 433 433.c Usage ./433 [option] ... -r, receiver (default) -t, transmitter -s BPS, bits per second, default 2400 (300, 600, 1200, 1800, 2400, 4800, 9600, 19200) -m COUNT, test messages, default 1000 ./433 -t -s4800 -m500 run as transmitter send 500 messages at 4800 bps ./433 -r -s4800 run as receiver (default), receive at 4800 bps -------------------------------------------------------------------------- */ #define PREAMBLE 0x21 #define SYNC 0xAA int rx = 1; /* defaults to receiver end */ int messages = 1000; /* default send 1000 test messages */ speed_t speed = B2400; /* default to 2400 bps */ struct termios orig; int filedesc; /* prototypes */ int openSerialPort (char * device, int bps); void tx_message (int fd, int mlen, char * dat); int rx_message (int fd, char * dat); int initOpts (int argc, char *argv[]); void tidyup(void); int main(int argc, char *argv[]) { int i, c; char buf[512]; initOpts(argc, argv); filedesc = openSerialPort("/dev/ttyAMA0", speed); if (filedesc == -1) exit(1); atexit(tidyup); if (rx) { while(1) { usleep(100); c = rx_message(filedesc, buf); if (c > 0) { buf[c]=0; printf(buf); } } } else { for (i=1; i<=messages; i++) { sprintf(buf, "message #%d\n", i); tx_message(filedesc, strlen(buf), buf); usleep(500); /* delay between messages */ } } } void tidyup(void) { fflush(NULL); /* flush output */ /* important to use TCSAFLUSH, otherwise buffered messages will be lost */ tcsetattr(filedesc, TCSAFLUSH, &orig); /* restore original serial settings */ } int openSerialPort(char * device, int bps) { int fd; struct termios new; char buf[128]; fd = open(device, O_RDWR | O_NOCTTY | O_NDELAY | O_NONBLOCK); if (fd == -1) { sprintf(buf, "openSerialPort %s error", device); perror(buf); } else { tcgetattr(fd, &orig); /* save current serial settings */ tcgetattr(fd, &new); cfmakeraw(&new); fprintf(stderr, "speed=%d\n", bps); cfsetispeed(&new, bps); cfsetospeed(&new, bps); tcsetattr(fd, TCSANOW, &new); /* set new serial settings */ fcntl (fd, F_SETFL, O_RDWR); } return fd; } int checksum(int len, char * dat) { int cksm; int i; cksm = 0; for (i=0; i<len; i++) cksm ^= dat[i]; return cksm; } void tx_message(int fd, int mlen, char * dat) { char buf[300]; char cksm; int wrote; buf[0] = SYNC; /* gives time for the receiving uart to sync */ buf[1] = SYNC; /* gives time for the receiving uart to sync */ buf[2] = PREAMBLE; buf[3] = mlen; memcpy(buf+4, dat, mlen); cksm = checksum(mlen+2, buf+2); buf[mlen+4] = cksm; wrote = write(fd, buf, mlen+5); if (wrote != (mlen+5)) printf("short write %d\n", wrote); } void printBuf(char * buf, int bufLen) { int i; for (i=0; i<bufLen; i++) { if (isprint(buf[i])) printf("%c ", buf[i]); else printf("%02X ", buf[i]); } printf("\n"); } int rx_message(int fd, char * dat) { static int posBuf=0; static char msgBuf[512]; int i, scanning, mlen, validMessage; char cksm; char * ptr; validMessage = 0; i = read(fd, msgBuf+posBuf, sizeof(msgBuf)-posBuf); if (i>0) { posBuf += i; scanning = 1; while (scanning) { if (msgBuf[0] != PREAMBLE) { /* find message start */ ptr = memchr(msgBuf, PREAMBLE, posBuf); if (ptr != NULL) { /* preamble found, discard previous junk */ i = ptr - msgBuf; posBuf -= i; memmove(msgBuf, ptr, posBuf); } else { /* no preamble found, discard junk */ posBuf = 0; scanning = 0; } } if (posBuf > 2) { /* we have enough to calculate size */ mlen = msgBuf[1]; if (posBuf > (mlen+2)) { /* we have enough for a message */ cksm = checksum(mlen+2, msgBuf); if (msgBuf[mlen+2] == cksm) { /* valid message received */ validMessage = 1; /* copy message to callers buffer */ memmove(dat, msgBuf+2, mlen); /* remove from receive buffer */ posBuf -= (mlen+3); if (posBuf) memmove(msgBuf, msgBuf+mlen+3, posBuf); scanning = 0; } else { /* corrupt message or invalid preamble. Delete preamble and search for another */ msgBuf[0] = 0; } } else scanning = 0; } else scanning = 0; } } if (validMessage) return mlen; else return 0; } int initOpts(int argc, char *argv[]) { int opt; while ((opt = getopt(argc, argv, "m:rs:t")) != -1) { switch (opt) { case 'm': opt = atoi(optarg); if (opt>0) messages = opt; break; case 'r': rx = 1; break; case 's': opt = atoi(optarg); if (opt == 300) speed = B300; else if (opt == 600) speed = B600; else if (opt == 1200) speed = B1200; else if (opt == 1800) speed = B1800; else if (opt == 2400) speed = B2400; else if (opt == 4800) speed = B4800; else if (opt == 9600) speed = B9600; else if (opt == 19200) speed = B19200; break; case 't': rx = 0; break; } } return 0; }
Re: UART RX TX problem
To me that would suggest a problem with the connections or with the Pi. Bad connections would seem more likely.
