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products:sbc:edge-2l:applications:gpio:uart
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products:sbc:edge-2l:applications:gpio:uart [2026/05/11 02:40] nick removed |
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| - | Bold Text ~~tag> | ||
| - | ====== Edge-2L UART ====== | ||
| - | |||
| - | ** Edge-2L [[products: | ||
| - | |||
| - | /* | ||
| - | ===== Introduction ===== | ||
| - | |||
| - | This page introduces the usage of hardware UART on [[products: | ||
| - | |||
| - | <WRAP important > | ||
| - | For Edge-2L, in order to use the UART , you need to attach the IO extension board. | ||
| - | </ | ||
| - | ===== UART Information ===== | ||
| - | |||
| - | | | ||
| - | ^ Edge-2L | ||
| - | | ::: | ::: | ||
| - | ===== Enable UART ===== | ||
| - | |||
| - | In order to use the UART, you need to enable the UART function via [[products: | ||
| - | |||
| - | |||
| - | Edit ''/ | ||
| - | |||
| - | e.g. Enable '' | ||
| - | |||
| - | ```shell | ||
| - | fdt_overlays=edge-2l-io-uart | ||
| - | ``` | ||
| - | After reboot, you will see the UART device node. | ||
| - | |||
| - | ```shell | ||
| - | $ ls /dev/ttyS3 | ||
| - | /dev/ttyS3 | ||
| - | ``` | ||
| - | |||
| - | ===== Demo Source Code ===== | ||
| - | ```c uart.c | ||
| - | #include < | ||
| - | #include < | ||
| - | #include < | ||
| - | #include < | ||
| - | #include < | ||
| - | #include < | ||
| - | |||
| - | // set serial path | ||
| - | #define SERIAL_PORT "/ | ||
| - | |||
| - | int main() { | ||
| - | int serial_port; | ||
| - | struct termios tty; | ||
| - | | ||
| - | // open | ||
| - | serial_port = open(SERIAL_PORT, | ||
| - | if (serial_port < 0) { | ||
| - | perror(" | ||
| - | return 1; | ||
| - | } | ||
| - | | ||
| - | // Configuration of serial | ||
| - | memset(& | ||
| - | if (tcgetattr(serial_port, | ||
| - | perror(" | ||
| - | close(serial_port); | ||
| - | return 1; | ||
| - | } | ||
| - | | ||
| - | cfsetospeed(& | ||
| - | cfsetispeed(& | ||
| - | | ||
| - | tty.c_cflag |= (CLOCAL | CREAD); | ||
| - | tty.c_cflag &= ~PARENB; | ||
| - | tty.c_cflag &= ~CSTOPB; | ||
| - | tty.c_cflag &= ~CSIZE; | ||
| - | tty.c_cflag |= CS8; | ||
| - | | ||
| - | // write configration to serial | ||
| - | if (tcsetattr(serial_port, | ||
| - | perror(" | ||
| - | close(serial_port); | ||
| - | return 1; | ||
| - | } | ||
| - | | ||
| - | // loop test | ||
| - | while (1) { | ||
| - | // receive data | ||
| - | char received_data[64]; | ||
| - | if (read(serial_port, | ||
| - | // get data | ||
| - | printf(" | ||
| - | } | ||
| - | |||
| - | // Only send " | ||
| - | char data_to_send[] = " | ||
| - | write(serial_port, | ||
| - | | ||
| - | // sleep 100ms | ||
| - | usleep(100000); | ||
| - | } | ||
| - | | ||
| - | // close | ||
| - | close(serial_port); | ||
| - | | ||
| - | return 0; | ||
| - | } | ||
| - | ``` | ||
| - | |||
| - | Compile test code: | ||
| - | |||
| - | ``` | ||
| - | $ gcc uart.c -o uart | ||
| - | ``` | ||
| - | |||
| - | Run '' | ||
| - | |||
| - | ``` | ||
| - | $ ./uart | ||
| - | ``` | ||
| - | |||
| - | After connecting PIN12(STX), PIN14(CSO) and GND to PC, open ttyUSBX and input hello | ||
| - | |||
| - | ``` | ||
| - | 1 hello | ||
| - | 2 Hello, UART! | ||
| - | ``` | ||
| - | |||
| - | Check output data: | ||
| - | |||
| - | ``` | ||
| - | $ ./uart | ||
| - | Received: hello | ||
| - | ``` | ||
| - | |||
| - | ===== Disable UART to Use GPIO ===== | ||
| - | |||
| - | If you want to use normal GPIO instead of UART, you can remove the UART node in [[products: | ||
Last modified: 2026/05/11 02:40 by nick