Questions tagged [uart]

a Universal Asynchronous Receiver/Transmitter, better known as serial port

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Multiple Rpi Serial Ports Problem

So I am undergoing a project where I will need to add 20 UART (RX/TX) to a single raspberry Pi 3. Each device runs at 9600 After looking at the pi, I found it only has 1 UART on it. What would be ...
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3answers
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Disable UART such that it will not be on during the boot process, but only after

I am using UART sensors that do not allow the RPI to finish the boot when the serial console and the bluetooth are on. I did disable them using the dtoverlay=pi3-disable-bt in /boot/config.txt and ...
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2answers
877 views

what is the equivalent of scp for the serial console?

I am configuring my raspberry pi device of the serial console (like this https://learn.adafruit.com/adafruits-raspberry-pi-lesson-5-using-a-console-cable/overview) How can I do the equivalent of scp? ...
2
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1answer
484 views

How tp get USB to USB UART console without linux

I'm trying to develop my own OS kernel from scratch for the raspberry pi and I want to be able to debug my code from my computer over putty through a cable. Now I've did a little googling and found ...
2
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1answer
10k views

Set default baud rate on /dev/ttyAMA0 and keep after reboot

I have a ITead Studio GPS attached to my RasPi Model B 2.0's UART serial port and it's specifications require baud rate to be set at 38400. I am using gpsd on Raspbian, which attempts to use baud ...
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2answers
35 views

How can I prevent Raspbian from resetting user privileges on /dev/tttyS0?

I've got a GPS module hanging on the TTL UART wires of my Pi 3B. I don't access the module directly, but via gpsd. Now I've got the following issue: At every reboot, Raspbian (Buster) seems to reset ...
2
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1answer
1k views

How can I disable the serial console on distributions that use U-Boot?

I'm trying to use a Raspberry Pi with a UART peripheral and a non-Raspbian Linux distribution. It seems like most of these distributions use U-Boot. I'm running into two problems: U-Boot outputs on ...
2
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1answer
349 views

How to connect 3V3 UART logic level to the 5 V RS232 C logic level?

How to connect the 3.3 V Raspberry Pi UART logic level to the 5 volt RS232 C logic level?
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2answers
5k views

Size of serial port read size in c

I have a Raspberry Pi 3 and I'm currently use read(2) system call to read data from serial port. At this moment, I'm reading byte by byte from port with; rc = read(uart_fd, &byte, 1); I'm ...
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2answers
4k views

How should I properly communicate 2 Raspberry Pi via UART?

I'm testing serial communication with Python pyserial module. I try to communicate some strings between two Raspberry Pi's ... I tested transmitter and receiver code at same device connecting it's ...
2
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1answer
1k views

Unable receive character properly in UART

I am trying to send and receive character using UART (GPIO14 as Tx & GPIO15 as Rx). I can transmit character successfully which I can check on minicom. Now I have short my RX and Tx pin so that I ...
2
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4answers
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UART sends but not receives but works if tx-rx are bridged

I have this strange problem... When I connect TX and RX pins together (GPIO 14 and GPIO 15, Rev1) and I run minicom, I see everything that I type... so it works. But when I connect TX RX with an USB ...
2
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1answer
91 views

Connect SIM800L with other GPIO pins in Raspberry PI 3B+

I have a SIM800L module and a keypad module that I want to connect to the raspberry pi 3B+ but then when I had all my modules and stuff I found out that the raspberry pi had only 1 UART (1RX & 1TX)...
2
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1answer
159 views

baudrate usart5 raspberry pi 4

I need to connect raspberry pi 4 to a microprocessor, and I am using uart5 (dtoverlay=uart5 at the end of config.txt). What I need is to change the baudrate to 4800, because this is the baudrate I use ...
2
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1answer
305 views

Strange behavior when using UART0

I need to use all five of the PL011 UARTs on a Raspberry Pi 4. I am having no problems with UART2 - UART5. It is only UART0 that is giving me problems. I connect a serial cable from a laptop to the ...
2
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2answers
91 views

Why is UART-USB link inserting many unexpected bytes when using /dev/serial0 with dev/ttyUSB0?

My first post and my first Pi project. I'm experimenting with data transfer between Pi and external UART-enabled devices. As part of this, I want to prototype simple bi-directional data transfer ...
2
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1answer
380 views

Rpi3B+ Control Half Duplex UART Bus Servo DynaMixel AX-12A, HiWonder LX-224HV Problem

I have a project to make mobile robot with Dynamixel AX-12A as the wheel, so i changes the AX-12A to Wheel Mode with CM-530 and it works well. I follow the guide from http://www.oppedijk.com/robotics/...
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1answer
6k views

How to enable CTS/RTS (Hardware Flow Control) for MAIN UART (PL011) on Raspberry Pi 3 B+ module?

I am working on Raspberry Pi 3 B+ module with raspbian stretch lite os. I Wants to configure UART interface on Raspberry Pi 3. I have referred the following link & I am able to test UART ...
2
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1answer
656 views

How do you use both USB Serial Gadget and UART on Pi Zero?

Just like the title says, I want to use both the GPIO UART and the USB Gadget at the same time. Background: I've been working on modding up one of the Adafruit IoT printer projects, which uses the pi ...
2
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1answer
2k views

Raspberry Pi how to get data from serial port in GNU screen

I have sample app that wait on signal from IR sensor that is connected to GPIO15 and 14: ser = serial.Serial(port="/dev/ttyAMA0",baudrate=115200, timeout=1) io.add_event_detect(15,io.RISING, callback=...
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1answer
551 views

Using the UART GPIO pins on a pi 3 to output characters to a TI MSP430

I'm currently building a remote controlled motor driven robot that is taking USB remote input, and output said input through the UART TX pin to a Texas Instruments MSP430 launchpad, that is connected ...
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3answers
2k views

How to free the UART pins of Raspberry pi B+ from acting as a kernel console?

I have a Raspberry Pi B+ for my project with Raspbian Jessie OS installed on it.. I have to receive "Real-time" electric current values coming from a wireless Nordic module. So to start this serial ...
2
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1answer
1k views

Resetting a Raspberry Pi from a USB (CH340G) UART

I want to use a CH340G USB UART to connect to the console of my raspberry pis - something like this: http://www.ebay.com.au/itm/To-TTL-USB2-06Pin-CH340G-Converter-for-STC-Arduino-PRO-Instead-of-CP2102-...
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1answer
2k views

Redirecting stdout and stderr to UART

I am building my own cross-linux-from-scratch (CLFS) system for Raspberry Pi. I already build whole system, I prepared SD card and now I try to boot. I am redirecting all kernel output to serial ...
2
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3answers
2k views

RF transceiver and XBee module, both need UART?

I'm working an a home automation project, using a Raspberry Pi. What I want to do is connect an RF 433 MHz transmitter to control RF-controlled light switches, and a ZigBee/XBee module to connect to ...
2
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1answer
347 views

Remote command execution over UART

I have connected my computer to the raspi over UART and was wondering if I could remotely execute a command. My intention is to log stats of my raspi CPU usage on my computer at specific intervals. I ...
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1answer
1k views

Testing bluetooth communication on RaspberryPi

I am a beginner at RaspberryPi programing so I hope the question doesn’t sound dumb. I would like to test a communication between two bluetooh modules in SPP mode. Is it possible to connect them both ...
2
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1answer
1k views

Enable mini UART on CM3

I wan't to enable the mini UART on a CM3 for Linux console access in emergency cases. The full UART will be used for other purposes. With a newly flashed CM3 I can access the Linux console using ...
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2answers
686 views

Using UART from USB C

So basically my Alienware R4 17" 2017 model has USB C ports. I think USB C ports are a standard and operate at 20 volts, 5 amps, and 100 watts for power and charging. I have a Pi 3 and Pie 3 Model B+....
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1answer
1k views

Blank terminal in Pi0 UART connection

Following this tutorial exactly: https://learn.adafruit.com/adafruits-raspberry-pi-lesson-5-using-a-console-cable/overview i.e.: Drivers are installed UART line is added and enabled I get a blank ...
2
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1answer
878 views

Error message when setting parity for serial on rasp pi 3

I am trying to get the uart serial to work but when I try to set the parity the following error comes out. pi@pi3:~ $ python3 Python 3.4.2 (default, Oct 19 2014, 13:31:11) [GCC 4.9.1] on linux Type "...
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1answer
444 views

Can the raspberry pi be used as a serial converter to debug other boards?

I have a board running linux and it doesn't boot when connecting a specific hardware, the board doesn't even load the kernel so i have to use a serial cable to see what's causing the issue, currently ...
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2answers
972 views

How to disable DMA when using UART on the Raspberry Pi 2

I have a latency issue when using UART on Raspberry Pi 2 and I want to disable DMA when using UART driver. I know that the Raspberry Pi 2 uses ampa_pl011 and I don't want use DMA. Can you tell me how ...
2
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1answer
1k views

Disable Raspberry Pi UART

Is it possible to disable UART in Raspberry Pi?? I undid what I have done to enable UART in Raspberry Pi, but UART pins(8 and 10) can't be freed because when I tested with an LED, it glows on boot-...
2
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1answer
2k views

Same output on TXD and RXD

I wanted to read some data from an external microcontroller via the UART, but couldn't get any communication working. After checking the RXD and TXD pins, I saw that there is also a signal on the RXD-...
2
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1answer
3k views

Problem with UART

I've a Raspberry Pi Model B. I want to connect its serial output to my PC and view the logs generated by it. My serial to USB converter board uses FTDI FT232RL and supports both 3.3V and 5V (using a ...
2
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1answer
2k views

Raspberry Pi on AVC-LAN / IEBus

I'm planning on using my Raspberry Pi in my car as an XBMC server. I'll be able to select songs/videos using the Android remote control app, but it occurred to me that it would be really neat if I ...
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0answers
91 views

pySerial - UART - Determining when a message has actually been sent (callbacks?) (RTS/CTS hacking?)

For reasons (explained at the end of the post) I need to have a pin change state immediately as the UART finishes outputting a set of bytes. I'm using pyserial & pigpiod on a RPi3B+ and bluetooth ...
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0answers
599 views

Pi CM4 - Additional UART enabling does not work

I have a Compute Module 4 here, and i want to enable more UART ports The Datasheet, Page8 specifies that uart 2-5 can be enabled since their ports are not used by anything else I've run raspi-gpio get ...
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0answers
74 views

Mini-UART on RPi 3 and earlier loses synchronization if parity bit used

I have a sensor which every 1 second spits out a 32-character serial stream at 9600 baud. I hooked it up to the mini-UART pins on the GPIO connector. What I saw was bad data. After staring at the ...
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0answers
105 views

How can I reconfigure the UART on the fly?

I have a Pi Zero with Raspbian which I'd like to use as a logger device with WiFi (it's not a W, I'm using an external WiFi stick). I need the UART to communicate with a microcontroller but sometimes ...
2
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1answer
2k views

SIM800 GSM Module To Raspberry Pi UART Serial Communication Problem

I am new to Raspberry Pi Zero and I want to connect it with a GSM module for GPRS connectivity. I bought the SIM800A GSM module but its LED is not even blinking one single time. I am able to turn on ...
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0answers
257 views

SPI0 and UART0 interference caused by SPI interrupt

I have a raspberry CM3 running a custom Linux version created by buildroot (kernel: 4.19.44-v7). The CM3 is configured to be part of a measurement system that is used on a quad-bike (so a lot of ...
2
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1answer
1k views

RPi Zero: Two UART devices at the same time

I need to read UART data from one device, and send different data to the other device, all via raspberry pi zero. It has only one UART TX and one UART RX on GPIO pins, but I heard that it is possible ...
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0answers
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How do I test if my UART port is working? Simple example... loopback-test

I am working on a NMEA(GPS)-datalogger for a drone. I followed the tutorial from fishandwhistle and createt this script: #!/usr/bin/python3 import os, time, sys, glob, datetime, syslog, pynmea2, ...
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0answers
3k views

Raspberry pi 3 uart not working

I've done almost any tutorail I found in the internet, but I cant get successful communication with uart in RPI3 Ubuntu Mate. I've added enable_uart=1 and dtoverlay=pi3-disable-bt and core_freq=250 ...
2
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1answer
1k views

UART pins not reading sensor output RPI3

This is my first pi project so im a bit new at this. Im trying to connect a senseair K-30 CO2 sensor to the pi via the UART gpio pins. This is the sensor I am using: https://www.co2meter.com/products/...
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0answers
415 views

Lost Serial on Pi3 running Pixel

I have just upgraded to the latest OS Raspbian Pixel and my serial connection has stopped working. I know that the hardware is configured correctly as it worked pre-update. I have updated to the ...
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0answers
970 views

u-Blox SARA and ModemManager

I have a u-Blox SARA-U270 device connected to a Raspberry Pi 3 via UART GPIO pins, that I am trying to use for a 3G connection as a backup. I would like to manage this via NetworkManager/ModemManager ...
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0answers
846 views

How can I make the ITEAD PN532 work on the R-Pi via UART?

I have used the Adafruit PN532 before on the R-Pi (A and B+) via UART and it works just fine but I haven’t been able to make it work for the ITEAD. The ITEAD supports I2C, SPI and UART. On this link, ...

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