Raspberry Pi Stack Exchange
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Questions tagged [uart]

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

A Universal Asynchronous Receiver/Transmitter, abbreviated UART, is a piece of computer hardware that translates data between parallel and serial forms. UARTs are commonly used in conjunction with communication standards such as EIA, RS-232, RS-422 or RS-485. The universal designation indicates that the data format and transmission speeds are configurable. The electric signaling levels and methods (such as differential signaling etc.) are handled by a driver circuit external to the UART.

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How to get more than one uart interface

Ok, I have one uart interface (TXD GPIO 14, RXD GPIO 15). I want at least one more uart interface. Possible solutions: Bit banging: Use two unrelated spare GPIOs. I understand that timing is a problem on a standard linux. Would it be reliable with…
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How do I connect my printer to the serial GPIO pins?

I've purchased a Mini Thermal Printer from Adafruit. The documentation states: This printer is ideal for interfacing with a microcontroller, you simply need a 3.3V to 5V TTL serial output from your microcontroller Since the serial pins on the…
Jivings
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How can I set the UART speed?

How should you set the baud rate of the UART Bonus question: What baud rates are available on the RPi? Edit: Since reading up from Steve's answer, I have found that there are two UARTs available. The mini-UART can work up to 32Mbaud, but has a small…
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Where are the uarts on the raspberry pi 4?

The raspberry pi 4 has at least two uarts (as shown here), I know where I can connect to one of them. Pins 8, 10 and 12 have a uart as an option. Source: This site describes accessing uart1, where is it? Do I have access to it?
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Disable DTR on ttyUSB0

I'm connecting from Pi to Arduino-clone board. The problem is, that I need to disable DTR line, in order to prevent Arduino from resetting on connect. I have read that on RPi is not possible to control DTR, DCD and other lines. Is it this true for…
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PiGPIO Library Example for Bit-Banging a UART

The PiGPIO library http://abyz.me.uk/rpi/pigpio/index.html mentions that one of it's features is "software serial links using any user gpio". I take this to mean that you can use it to generate a software UART on any 2 free GPIO pins. In the…
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Pi 4 I/O interface options... and where to find them

The BCM2711's hardware documentation lists multiple I/O interface options. Among others these are: up to 6 × I2C, up to 6 × UART (muxed with I2C), up to 6 × SPI (only five exposed on Raspberry Pi 4B) The Pi 4 however shares the pinout of its…
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True 9-bit serial port data?

I have an existing, half complete, vending machine project running on an Atmel UTC, which I want to port to the Pi. In order to talk to peripherals, such as coin acceptor, it has to support Multi-Drop Bus which has a 9-data bit serial port…
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Is there a way to make a regular GPIO pin into a Tx UART pin?

I'm working on a project that is going to need two different UART interfaces. Is there a way to make a regular GPIO pin into a Tx UART pin, I don't need an Rx pin too. Is there a software solution in python maybe, as I doubt there is a hardware…
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How to connect SIM800 GSM ADD-ON to RaspberryPi 3

I am confused about how to connect SIM800 GSM module to RaspBerry PI 3. I connect the module to RaspBerry PI using the GPIO pins. What happends now? Are those GPIO pins automatically connected to RaspBerry PI? Should it already work? I no, do I have…
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Bit waveform clarification

I have been trying to learn more about bit transmission through the uart, and I have the following code in python to transmit information: import serial ser = serial.Serial( port='/dev/ttyAMA0', baudrate = 1000000, …
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UART RX stops reading data after working correctly

I'm trying to read an continuous stream of data from my device (laser altimeter). The device is connected to the UART Rx pin of raspberry Pi 3B+. Everything works fine with this python code: import time import serial try: ser = serial.Serial( …
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How to communicate between Pi 3 and an Arduino using UART from GPIO?

I need to transfer data between Arduino and Pi. I have an Pi 3, and I used a simple circuit with a voltage divider to deal with 3.3v vs 5v logic levels. But I got nothing. Then, I used only Pi3 with its TX and RX pins connected directly. I saw here…
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UART Output working on 57600 Baud but with 115200 only gibberish

I've got a strange problem with serial output. Using Wheezy and 8 Databits, 1 Stopbit, NoFlowcontroll, NoParity (config as stated in eLinux Wiki). With 57600 Baud everything works fine but with 115200 Baud all I receive is gibberish. My RasPI is…
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How can I test if the serial / UART is good on a Raspberry Pi?

I've purchased a used Raspberry Pi and have followed the instructions from Wolf Paulus's Journal to connect to the Raspberry Pi from my computer using a PL2303 USB adapter. The specifications on the PL2303 adapter say that it is for use with 3.3 V…
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