Questions tagged [uart]

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Enabling second UART in U-Boot

I am working on a project with SAMA5D3-xplained board with CortexA5 processor and embedded Linux. I would like to send and receive some data via UART during U-Boot is running and before a kernel is ...
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1answer
96 views

The linux boot message in dmesg doesn't output to uart

My problem is my linux is success for boot but there is no more boot message output to uart(ttyPS0) after "Starting kernel...". As you can see in the pic, there is a lot of boot message in ...
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21 views

Network use USART

Hy I wanted to implement a Network driver that uses the USART. So first I changed the Device-Tree to acces the USART. Then I started to create my Network driver. In the init() method of the driver I ...
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How to redirect GRUB2 output to a MMIO serial UART?

Is it possible to redirect GRUB2 output to a MMIO serial UART? For example I have a UART that is displayed in a Linux boot log as: AMDI0020:01: ttyS5 at MMIO 0xfedca000 (irq = 4, base_baud = 3000000) ...
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1answer
98 views

How are the TTY and serial_core related?

I need to write a new character device file for the UART, which allows a few more file operations than usually allowed (not just open, write, etc..) I'm on an embedded mainline linux kernel (v 5.4). I ...
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27 views

How does the kernel interacts with drivers and device tree?

I have an embedded linux system running on a board. I had, in the device tree, the uart device, and also a driver for that. In that case, after boot, I could see a /dev/ttymxc0 "file" in the ...
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46 views

Serial tty not working due to wrong DEVPATH

I am currently using a Banana Pi M2 Zero. I am having a bad time trying to make the UART work (no console, just serial communication.). ttyS0 is the console port (UART0), and it works OK through ttyS0....
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0answers
104 views

Use rs485 driver specifying the DE pin

On an embedded system (STM32MP1 w/ Yocto environment) I need to control an rs485 transceiver. Unfortunately, the DE pin of the transceiver is connected to a generic GPIO pin of the MPU and not to the ...
5
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1answer
245 views

How to active the second console to a FreeBSD guest running in bhyve?

Background I'm running FreeBSD 12.1-RELEASE as a host for bhyve virtual machines. I have a FreeBSD 12.1-RELEASE guest running inside a VM. I would like to have two TTY-class devices configured for it. ...
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0answers
997 views

Samsung SMT-G7401 hack

Samsung SMT-G7401 hack introduction I have an SMT-G7401_PCS01B (Horizon box) from UPC Switzerland and I would like to install debian or multimedia linux distribution on it if is it possible, if is ...
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1answer
992 views

Bash script - Watch serial-port for specific string, then send back commands

I try to use a bash script to watch the serial-port for a specific string. If this string is shown, some commands should be send back to the connected device. It´s a router I am connected to. It is a ...
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1answer
188 views

What does PS in ttyPS* stands for?

What does PS in ttyPS* stands for? Where, in general, can I find the expanded names of devices under /dev?
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1answer
31 views

Raspberry Pi UART not working

I've tried everything. Raspberry Pi 4 echo works. Linux echo works. But when I connect the two UARTs together, no information is sent.
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1answer
86 views

Is there a limit to the number of FTDI connections on Debian 9?

I have a Debian 9 box, and if I plug in 1 of my devices, its UART shows up in both lsusb and in the output of ls /sys/bus/usb-serial/devices/. When I attach 2, the 2nd one always shows up. But for ...
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1answer
201 views

Read Write Serial Device not Working in Shell Script

I have a USB serial device connected to my Linux VM (Ubuntu 18.04LTS). It accepts byte streams in certain format and will return some content. To read from the device, I have written the following ...
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1answer
156 views

BeagleBone Slackware UART issue

I'm working with a custom made image of Slackware ARM 14.1 with kernel 3.8.X since about 3 years and now needed to upgrade kernel for cdc-acm driver and watchdog. I've tried different kernels from ...
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1answer
519 views

UART to UART tcp/ip connection

Need to transmit and receive data(TCP/IP) between 2 raspberry through serial tx/rx pins (/ttyAMA0). Best way to do it? Better if this will be done from kernel space. Thanks!
2
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1answer
1k views

Debian not recognizing my ttyS0 / console redirection not working

I have a fitlet2 (https://fit-iot.com/web/products/fitlet2/) which has a serial port. I can connect to the serial port of the fitlet2 with screen from my computer (screen /dev/ttyUSB0 115200) and ...
1
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1answer
587 views

Mirroring USB HID signals on Open WRT through UART [closed]

The setup: a Linkit Board (Smart 7688 Duo) running OpenWRT and a generic keyboard connected on the USB host. The goal: dumping the signal we get from the /dev/input/event0 and send it through the ...
2
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1answer
494 views

Hardware controlled RTS on tty

I have a UART whose RTS pin is connected to an external RS485 transceiver, so that asserting the RTS pin would set the transceiver to send mode. I thought I could configure the serial port to use the ...
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2answers
8k views

Retrieve file over serial without kermit and lrzsz

I have an embedded Linux on a custom board and I would like to send and receive file over its serial port. The only way to communicate with this device is over serial and the device offers a console ...
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0answers
2k views

Utilizing UART/Serial port driver inside another Linux module/driver

I am implementing a network module/driver in Linux which uses net_devices structure. And so far I have been able to add and remove my module to and from kernel space using insmod command. Via ifconfig ...
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0answers
434 views

WvDial serial communication not working with uart /dev/ttySAC4, but works with `screen`

I have embedded system based on Samsung Artik 710 board connected to Fibocom G510 cellular modem module via UART (two lines - RX and TX). When I try to communicate with modem using screen - modem ...
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0answers
110 views

Strange serial port behaviour on Raspberry PI

I'm trying to receive serial data on a Raspberry Pi through the GPIO15(RXD) pin. I have the following python script: serPort = serial.Serial("/dev/ttyAMA0", baudrate=2400) while True: rcv = ord(...
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0answers
664 views

How to Verify that a UART is Enabled on a Beaglebone Black

Question Is the existence of a /dev/ttyO* symlink evidence that the corresponding UART device is enabled? If not, how can I check whether or not the UART has been successfully enabled? Details I'm ...
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3answers
7k views

Failing to Enable UARTs on Beaglebone Black

Short and General Question I'm running Debian 9 (Stretch) on a Beaglebone Black with kernel 4.9. I have tried following the instructions that I've found online, but have thus far been seemingly ...
3
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1answer
408 views

How can I determine if a latency is due to a driver or the scheduler?

Using an oscilloscope and toggling some pins I sometimes see latencies of 1-2 seconds from when an 8-byte UART packet is transmitted to when a blocking read returns. The packets are 1 second part with ...
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0answers
530 views

Display PXE Network Boot Process in VirtualBox Serial Console

I want to start a VirtualBox VM in headless mode and view the network boot process in the terminal via a serial console (e.g. using screen or minicom). How do I accomplish this? Additional context ...
3
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1answer
1k views

What are the implications of setting the baud rate of a terminal from userspace?

Sometimes I just need to read from a serial device, so I skip the complexities of minicom or screen and just cat. However, this only works if I first set the baud rate of the terminal using stty <...
3
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1answer
8k views

socat - UART logging and redirecting

I am currently trying to log all communication from and to /dev/ttyUSB0 and simultaneously be able to connect minicom/screen to the same device for interaction. I tried a couple of tools and ...
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1answer
17k views

How to use UART pins on Orange Pi zero?

I want to use UART1 or 2 (see picture) on the Orange Pi zero. But when I try to open the port with screen /dev/ttyS1 Screen terminates. I found here that I needed to add "overlays=sun8i-h3-uart1" in ...
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1answer
83 views

Copying or redirecting text as input to UART, need to enforce slower bandwidth

Basically i'm completely sick of typing lots & lots of text. Obviously want type it in file, push it to UART U-Boot, then modify file, try again. But neither Shift+Ctrl+C over screen ttyUSB0 ...
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0answers
71 views

AT91SAM9260EK upgraded kernel from 2.6 to 4.4, Serial port not working

Admittedly this is big kernel jump. 2.6 had no concept of device tree and I have not yet created device tree for my product. So just default device tree files with older form of UART settings in board ...
3
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1answer
1k views

Wireshark: Remote capture over UART

TL;DR: How to pipe properly over UART the output of a remote tcpdump to a local wireshark ? I try to capture packets that flow through an embedded device to which I don't have the ability to install ...
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1answer
2k views

What is the relation between UART and the tty?

When I write programs for my own FPGA, I must select UART to emulate a terminal and for my FPGA design but I don't know exactly what that means. I believe that UART is a basic serial transmission ...
1
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1answer
47 views

odroidxu4 changing default uart2 to uart0

previously thank you for watching this post. I have tried to run linux on odroidxu4 and of course the logs are written through uart2 (this uart seems default in odroidxu4) But what I'm trying to do ...
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1answer
537 views

serial DMA pausing after 2048 bytes

I have a sama5d36 device running Debian jessie (kernel 4.1.10) with a DMA USART. To get the DMA USART to output correctly I had to turn off ECHO and ONLCR. stty -F /dev/ttyS2 -echo -onlcr speed ...
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2answers
888 views

Detect what driver is loaded for a UART connected chip?

I'm trying to detect what driver is responsible for providing the HCI interface for the Raspberry Pi 3 Bluetooth module. Here is an equivalent of what I'd like to achieve but for a USB dongle. user@...
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0answers
220 views

Load a Bluetooth driver on top of a generic TTL-232R->USB cable

I have one of these TTL-232R->USB cables which I usually use to access a terminal on an embedded board. They are usually detected like this: [89702.948822] usb 2-3.7: new full-speed USB device number ...
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2answers
824 views

RaspberryPi serial port

I have a Display that I want to write to. This is possible over the serial port. When I use a USB to RS-232 Converter, that thing works like a charm. I even tried using only the RX, TX and GND wires ...
4
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1answer
778 views

How to configure embedded kernel to use serial line for PPP instead of TTY

I am about to start working on an embedded system which runs kernel v2.6.x. It is configured to use its serial line as a TTY (accessible via e.g. minicom, stty), but I want to run IP over the serial ...
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1answer
869 views

Linux USART Serial Port

I'm trying to set up a USART serial port on a custom board with a SAMA5D36 processor, but I am unable to read in data from a connected device. When I run setserial -g /dev/ttyS1 I get the following ...
4
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1answer
11k views

Kernel parameters “console” and “earlycon” refer to old hardware?

I first found this by investigating parameters for earlycon but found that the options for console look almost identical. Both are present below and were taken from this source: From documentation ...