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Questions tagged [uart]

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

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(Pico) USB serial connection having noise?

I'm having some trouble trying to make a simple USB IO demo to test the Pico. Apparently, the USB serial connection seems to be noisy, and always puts something into the UART buffer even though I am ...
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1 vote
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Connect several sim800l with external power supply to the uart of ip4 and floating ground

I am creating a circuit with several sim00l connected to different UARTs each with its own external power. But I'm curious if having other objects like cooler-fan connected to other GND of the rpi ...
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Raspberry pi 4, data received from UART different from USB serial

I'm new to Raspberry pi. I writing a program that send/receive data from serial. Everything works fine with the USB to RS232 cable, but now I'm testing with the UART pins to RS232, and the data sent/...
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Why does Pi Pico duplicate and mix-up characters received over UART when programmed in C?

I have a Raspberry Pi Pico whose Tx and Rx pins are wired to the Rx and Tx pins of a Wemos D1 Mini development board. The Wemos and the Pico are powered via an external 5V power supply (common ground)....
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How to use Raspberry Pi 4 with an USB to RS232 adapter cable over the serial port

I would like to use a Raspberry Pi4 to control a syringe pump [(see datasheet here and in particular the quick start manual on page1)][1] The connector cables I used are RJ11 from the Pump to RS232 (...
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1 answer
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How to clear UART RX error for pico (RP2040)?

While working with a RPi Pico UART RX routine in C using pico-sdk, I have realized that uart_get_hw(uart0)->rsr; reports an error - that is, it has a value different from 0 (in my case 13, which is ...
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-1 votes
1 answer
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Rx, Tx/UART not being detected by Pi? What is wrong?

I'm working on Serial communication between the Raspberry Pi and the Arduino, with the Raspberry Pi serving as master. I connected, using a logic level shifter, Arduino's Rx (Software Serial was used ...
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Enable shell interface on USB but not UART

I have a headless setup running on a CM3+ board. The custom interface PCB I'm using breaks out UART0 on pins 51 and 53, and USB on pins 165, 167 etc. The USB port usually has a WiFi antenna plugged ...
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-1 votes
1 answer
57 views

Turn LED off and on using I2C, SPI or UART GPIO Pin

I have project requiring several simple LEDs and buttons, MORE that the number of ‘simple’ GPIO pins. Can I turn the LED TOTALLY OFF and on using a IC2, SPI, or UART pin? Can those pins be programed ...
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Indecipherable Characters with UART on Pi 2

I am attempting to use the UART pins on the Raspberry Pi 2 to interface with the console port on a Cisco Access Point. I've stripped an old RJ45 cable to connect the right TX, RX and GND pins from the ...
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Conflict between UART and cv2 Video Capture

I am attempting to communicate with an Arduino through UART using an Raspberry Pi 4 Model B. The Python script is grabbing frames from a Raspberry Pi Camera Module v2, pre-processes them and checks if ...
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Raspberry pi and nextion touch screen communication using python

I have tested several python codes to set up the communication between raspberry pi and nextion touch screen (I used TTL serial GPIO 14 and 15). Unfortunately, the communication is not stable, the ...
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Update scripts on OS via USART interface and uC

I have connected CM 4 (IO Board) with STM32F103 via USART interface. My goal is to find correct way to update pythons scripts, system settings etc on my RPI OS without direct connection with board, ...
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1 answer
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Missing dtbo overlays in Yocto build for Compute Module 4, what do I need to get them added?

So I have a problem that I have half solved and was hoping someone would know how to solve the rest. So yesterday I encounted a problem that I asked and partially solved at the link below. CM4 Uart 0 ...
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Can't modify UART 5 baudrate

I'm trying to communicate a NUCLEO-F746ZG with a RPi-CM4 thru the UART5. I need, at least, a baudrate >= 4000000. Using the stty -F /dev/ttyAMA2 4000000 I get the "unable to perform all ...
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-2 votes
1 answer
155 views

UART make sure to prevent data loss; choppy binary transmission [closed]

If I use UART to send sensor data from a Pi Pico to another computer (received via /dev/tinyUSB0), does the "default protocol" have any sort of error correction? I guess I don't need to ...
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1 vote
2 answers
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Possible to send data from a Pi Pico via USB while running CircuitPython?

I have a question on the interaction between Pi Pico, CircuitPython, and USB. I need a way to send a data stream from the Pico to another computer where it will be received on a USB port (it's the ...
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1 answer
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How to connect Sim800c development board to raspberry pi 3

i bought this development board Professional Small Size SIM800C GSM GPRS Module Quad-band Development Board Module Suitable for Raspberry Pi (blue & silver) https://www.amazon.it/dp/B07NVZ59JS/ref=...
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ch341-uart converter randomly disconnects from Raspberry

I'm facing problem, with ch341 uart chip. ch341 works normally at startup for about 120seconds. After that it disconnects. I'm attaching dmesg bellow. What it could be a problem? Tried with different ...
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Connecting the pi to a pixhawk flight controller

I am building a drone using a Pixhawk 2.4.8 flight controller. I want to add a pi with a picam to my build. I have followed this manual for connecting the pi to the controller. Therefore I have made a ...
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  • 101
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1 answer
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How can I "test data" coming in to a Pi from an UART device connected via TTL-to-USB

I've got a Waveshare PN532 RFID reader/writer. I want to use it with a Pi 4B, but since it is already using a HAT with no free GPIO, I want to use it in UART mode, but not connecting to the GPIO pins ...
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1 answer
1k views

How many (usable) serial ports does Pi Zero 2 W have?

The Raspberry Pi 1, 2, 3 and Pi Zero / Zero W all have two UARTs (PL011 + mini UART). The Raspberry Pi 4 and 400 have six UARTs (5 x PL011 + mini UART). This is from the official documentation. I have ...
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2 votes
2 answers
355 views

Does a UART connection require shared ground?

I'm a novice with electronics but not Linux. This situation has had me scratching my head for two nights. I connected a Pi Pico to a Raspberry Pi 4 via UART, and managed to receive messages sent from ...
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1 answer
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Connecting Fingerprint Scanner without USB converter

I'm trying to connect a fingerprint scanner without using a USB converter. I have it connected to pins 8 and 10 (GPIO14 and 15). I was following a tutorial but it required me to use the command ls /...
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-1 votes
1 answer
66 views

GPS Daemon not working on RPi, but works on my Arch PC

I followed this Adafruit Tutorial; trying to make GPS Daemon work on RPi4- on Raspberry OS minimal. Here is my situation: I can see NMEA data is coming thru minicom -b 9600 -D /dev/ttyUSB0. There is ...
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Enabling uart0 (ttyAMA0) and uart1 (ttyS0) on CM3 with Ubuntu 20.04

I am trying to enable the onboard uarts with a CM3 running Ubuntu 20.04 Server. I had no problem changing /boot/config.txt on an older raspian image, but on this one it doesn't work. I would like ...
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1 vote
3 answers
74 views

UART data collection and logging taking too much time

So, I am sending data to RP1 B+ model through UART from a microcontroller. I am using minicom to collect data and log it in a .txt file. I am sending around ~800 kB of data and using a baud rate of 1....
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75 views

Serial communication over uart - Android raspberry pi 4

Is there a library/source code available for serial communication over uart for the raspberry pi 4 running Android?
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2 answers
87 views

Debugging potentially broken uart pins

I have recently been working on a bare metal project on a raspberry pi. I have been using a uart to usb cable to for logging, which has been able to send messages to my computer. Recently however, it ...
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1 answer
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UART Rx TX pins not reading sensor output RPI3

This is my first pi project so I'm a bit new at this. I'm 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/...
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0 answers
110 views

C# .NET Core application cannot open serial port

I'm running a .NET Core application on Raspberry Pi OS (32-bit Debian). pi@raspberrypi:~ $ cat /etc/os-release PRETTY_NAME="Raspbian GNU/Linux 10 (buster)" NAME="Raspbian GNU/Linux&...
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1 vote
2 answers
713 views

How to enable the second serial port on a pi4

I am trying to use the second serial port. In /boot/config.txt I have put at the end : # swap UARTs dtoverlay=pi3-miniuart-bt dtoverlay=uart2 enable_uart=1 I have checked and re-checked the pin ...
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  • 111
1 vote
1 answer
636 views

UART communication Raspberry Pi Pico to Raspberry Pi

*Update, new main.py for pico and read_serial for RPI 4. *I am having the same problem with uart.write(), see below. I am trying to communicate with a raspberry pi pico with my raspberry pi 4 over ...
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  • 111
1 vote
1 answer
104 views

How can I make gpsd restrict to a certain serial port?

After reinstalling Raspbian Buster I'm always running into an issue with my gpsd 3.17: Despite the fact that I start it with the corresponding device file /dev/ttyS0 as a parameter (because the GPS ...
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  • 445
1 vote
1 answer
144 views

unable to gps data serially in raspi 4

I am trying to get ublox zed f9p module work with raspi 4. I am using this module I am running on ubuntu 20.04 desktop version on raspi 4 and i have connected the module serially(/dev/ttyS0) to my ...
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2 votes
2 answers
47 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 ...
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-2 votes
1 answer
365 views

Raspberry Pi Zero w two UARTs

I use on my RPi Zero UART ports on GPIO 14&15 on device /dev/ttyS0, and that is ok. But I need another UART port, can I connect to micro USB port on board USB-UART converter CP2102 to get the ...
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-1 votes
2 answers
300 views

RPI0 W unable to read UART data

I have enabled uart serial port /dev/ttyAMA0 on my raspberry pi zero W. I was able to successfully connect the rpi uart rx and tx pins and check if i'm able send and receive data between these rpi ...
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1 vote
0 answers
46 views

My DT overlay doesn't work

I'm trying to activate the miniUART with RTS and CTS signals (on an RPi Compute Module). For this purpose I've created an overlay: /dts-v1/; /plugin/; /* Enable /dev/ttyS0 with RTS and CTS signals ...
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0 answers
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Raspberry Pi Zero W not interacting with GSM HAT

I have Raspberry Pi Zero W and this hat. I did the following things: disabled login shell through serial in rasp-config enabled serial port hardware in rasp-config removed console=serial0 in /boot/...
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0 votes
1 answer
156 views

Read from RFID sensor using UART

I have a board for the RDM6300 which can read RFID tags. I could successfully test the board using an ESP32. Here is the micropython code: from machine import UART, Pin import time uart = UART(1, ...
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1 answer
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RX pin of ttyS0 is always high

I am trying to configure a Pi 4 and eventually a CM3 for modbus communication. so far I have been able to see the TX send from the D+ and D- of the max485cpa+ but I have been unable to receive data ...
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0 answers
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How Install Ubuntu 21.04 (Desktop) on Raspberry Pi 4 using Serial Console? [duplicate]

Hello how can I install ubuntu desktop 21.04 on raspberry pi 4 using serial console? I want to use the Raspberry Pi 4 UART pins to communicate using TTL to USB convert device to my windows 10 OS using ...
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2 answers
1k views

How to enable both UART (ttyS0 and ttyAMA0) on Raspberry Pi 3b?

I've already read dozens of manuals and stack topics, but I do not figure out if it even possible run both UARTs on RPi 3B. Some tutorials advice to map uart to other pins in /boot/config.txt I tried ...
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0 votes
0 answers
44 views

UART communication between Rhino DC servo motor and RPi4 B

I want to communicate with this Rhino DC servo motor with RPi4 B. I enable uart3 in RPi4 by modifying the /boot/config.txt file. In this file, I add dtoverlay=uart3 in the last. When I used ls /dev/...
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1 vote
1 answer
1k views

multiple UARTs on the 40-pin

i am trying to connect two devices via UART to a raspberry 4. one being a stepper driver (i dont need much throughput), one being an image sensor (the higher the baud rate is i can get, the better). ...
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1 answer
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Transmitting a signal without an external transmitter [closed]

I found a repository called rpitx which can be used to transmit a signal (e.g. the signal of the keyfob of my gate). I'm wondering how this is possible without an external transmitter connected to the ...
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1 vote
0 answers
114 views

redirect U-Boot Console to UART4 in rpi cm4 board

I am using Raspberry pi CM4 for my project. The Hardware is designed in such a way that i need to redirect all the debug messages coming through serial UART0 to UART4. I Use U-Boot as a boot loader ...
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1 answer
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Slow UART communication between Raspberry Pi Zero and 4B using pyserial

I'm testing serial communication between two Pi's (Zero -> Pi 4) with Python pyserial library. I am using Zero as camera with preprocessing and sending preprocessed data to Pi 4 via UART (/dev/...
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1 answer
403 views

Rpi zero w is not recognized as com port

When I connect my Rpi zero w to my PC (windows 10 via usb cable, I cannot see it under com port devices of PC. I am connecting micro usb side to the socket labeled as USB on Rpi. I want to establish a ...
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