hello,
i have problems to send data over the uart0 on GPIO14 Tx
i hope someone can see what is wrong![:D]( "Very Happy")
i am trying things now for the whole day ![:x]( "Mad")
but i don't see it.
i am checking the data on a logic analyzer.
it is not working with the code a made also not with the shell comand.
so to test some things a give a command in the shell that send 1 byte: 0x55
but i see random values on the logic analyzer (every now and then it's OK), with the shell comand and also withe code i made.
the settings of the LA are correct, i check that with a other device who is sending serial data.
the code that i used in the shell:in: sudo nano /boot/firmware/config.txt
i add on the bottem of the file:i made a minimal code but that is al so not working:
i have problems to send data over the uart0 on GPIO14 Tx
i hope someone can see what is wrong
i am trying things now for the whole day 
but i don't see it.
i am checking the data on a logic analyzer.
it is not working with the code a made also not with the shell comand.
so to test some things a give a command in the shell that send 1 byte: 0x55
but i see random values on the logic analyzer (every now and then it's OK), with the shell comand and also withe code i made.
the settings of the LA are correct, i check that with a other device who is sending serial data.
the code that i used in the shell:
Code:
printf '\x55' > /dev/serial0i add on the bottem of the file:
Code:
[all]enable_uart=1dtoverlay=disable-btdtparam=uart0=onCode:
#include <stdio.h>#include <fcntl.h>#include <unistd.h>#include <termios.h>int main() { int fd = open("/dev/serial0", O_WRONLY | O_NOCTTY); if (fd < 0) { perror("open"); return 1; } struct termios tty; if (tcgetattr(fd, &tty) != 0) { perror("tcgetattr"); return 1; } // Set baud rate cfsetospeed(&tty, B9600); cfsetispeed(&tty, B9600); // 8 bits, no parity, 1 stop bit tty.c_cflag &= ~PARENB; // no parity tty.c_cflag &= ~CSTOPB; // 1 stop bit tty.c_cflag &= ~CSIZE; tty.c_cflag |= CS8; // 8 bits //tty.c_cflag &= ~CRTSCTS; // no flow control tty.c_cflag |= CLOCAL | CREAD; // enable receiver, ignore modem lines tty.c_lflag = 0; // raw mode tty.c_iflag = 0; // raw input tty.c_oflag = 0; // raw output tcflush(fd, TCIOFLUSH); if (tcsetattr(fd, TCSANOW, &tty) != 0) { perror("tcsetattr"); return 1; } unsigned char data = 0x55; if (write(fd, &data, 1) != 1) { perror("write"); return 1; } close(fd); return 0;}Statistics: Posted by trixo — Sun Jan 11, 2026 1:17 pm — Replies 7 — Views 96