Questions tagged [uart]

A UART (Universal Asynchronous Receiver Transmitter) is a piece of logic that sends and receives data on a serial port.

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3answers
783 views

Should I connect RXD to TXD and vice versa

The circuit below is used to flash firmware to an MCU. There is a micro USB port on the PCB which one uses to connect to a host computer. The USB lines (D+, D-, ..etc) then goe through a bridge chip ...
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Trying to find and bridge USART pins from the manual of an STM32 board

I am trying to solve an issue regarding a firmware with this 64-bit Nucleo Board. I have the hex file and can see the ready source code but when I upload the firmware I am not able to communicate ...
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24 views

STM32 uart interrupt not firing

After having a UART echo working on my nucleo F446ze, I am trying to get UART interrupts working. I thought all I had to do is : set the priority for the UART3 interrupt enable the USART3_IRQn ...
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3answers
81 views

2 UART Connections to MCU using the Same RXD and TXD Lines

I need to connect a GNSS module's RXD and TXD lines to my MCU. But the problem is I don't have any available UART connections on my MCU. There are 3 UART connections, one is used by flash, one is ...
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Raspberry Pi Pico: can read from FTDI dongle but can't write

I have a very weird issue with my USB FTDI uart dongle and Raspberry Pi Pico connection. The problem is that I can read data from the dongle, but not write to it. Raspberry Pi Pico operates at 3.3v ...
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1answer
33 views

Using din rail terminal to UART communication

Can I use din rail terminal to do the communication between arduino and sensor using uart protocol? Using din terminal can I have problems? Or is better to use DB9 connector? The distance is 4m and ...
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0answers
52 views

STM32 UART goes crazy

Im' working with a STM3f429 dev board and a Mipot 32001353 LoRa module. This module communicates over UART. I have initialized my UART interface with cubeIDE. When i don't connect the wire between TX ...
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1answer
35 views

Using SPI with ESP8266-01

I'm pretty new to ESP8266 and all these low-level stuff. I recently purchased a ESP8266-01 and started learning about it and playing around with it, and I have a few questions: First, I found on the ...
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1answer
91 views

RS-485 module not transmitting LF and CR

I am working on a project that involves two ATMEGA328p MCUs communicating over long distance (between two floors of a building). One is master and the other one is slave. The master always initiates ...
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4answers
147 views

UART=Hardware, SPI=Protocol?

I read in few places, one of them is this, that one of the main differences between UART and SPI is that the former is a type of hardware and the latter is a protocol. I'm having hard time to fully ...
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TM4C129EXL: Read UART data form RX TX pins and display on console in Code Composer Studio

I am using a TM4C129EXL Tiva-C launchpad and I am facing difficulty in reading the data from the RX and TX pins which are connected to a NEO-6M GPS module. The NEO-6M led indication shows that ...
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1answer
36 views

Wiring SMD Micro USB to ESP32 MCU

I am trying to connect a SMD micro USB to my ESP chip using a USB to UART bridge. The schematic being followed is attached below. But there are a few things on the diagram that I find confusing, the ...
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2answers
58 views

Serial port from PC not reaching the MCU

I'm trying to send some data from the PC to my STM32L432KC Nucleo board using UART. Transmitting data to the PC works just fine, I'm receiving data through the STLink Virtual COM Port which I can see ...
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1answer
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Circuit for Atmel (now Microchip) Single Wire Interface (SWI) using actual TTL UART?

Atmel defines a Single Wire Interface (not to be confused with 1-Wire) for their ATSHA204 chip. AVR274 describes how to use a UART for SWI. But how to wire a generic TTL UART for this?(for example ...
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Why does this UART Daisy Chain keep frying?

My team and I are creating a project where a sensor board is controlled by two Arduino Nano's, connected using a UART daisy chain. Whenever the board is turned on using a USB connection, the Arduino's ...
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2answers
414 views

What was the communication protocol used on board the Apollo moon lander?

It seems that the development of TTL was contemporary ~1961 the maiden moon landing of the Apollo vehicle, while the development of one of the oldest digital signalling standards RS232 using the UART ...
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4answers
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Is there a way I can convert from USB to LVDS UART (~1Mbps)? [closed]

I'm working on a spacecraft that requires very low noise levels so it was requested that we pursue LVDS UART. So it's using something similar to RS-422 because it's differential, but instead of a ...
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1answer
37 views

PCB GNSS module with RPi

I am trying to get a GNSS module to communicate with a raspberry pi serially. I was attempting to set this up with an ESP module but I don't think it will work, or at least I am missing something. In ...
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1answer
61 views

ESP32 UART to Raspberry Pi I2C

I am trying to understand how to connect an ESP32's UART pins to my raspberry pi 3B+'s I2C pins. I see several bridge chips available for this like TI's MSP430 Datasheet. But I am not very circuit ...
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2answers
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In STM32, How to check the UART Serial Buffer If They Are Available using HAL Library

I am using STM32F429 in my project which connects to an ATmega2560 thru UART. In arduino, there is a function Serial.Available() to check if the serial buffer is empty or not. Is there a function in ...
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3answers
2k views

What would it take to make a PS/2 keyboard interface hot-swap?

A long time ago, I had to service some of the early Compaq Desktop PCs. They used to have fuses on the motherboard that blew when a customer hot-plugged a keyboard. I found this when googling on the ...
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1answer
38 views

MAX3485 pull-up pull-down resistors

I want to use the following MAX3485 chip: https://datasheet.lcsc.com/szlcsc/2006181334_UMW-Youtai-Semiconductor-Co-Ltd-MAX3485ESA_C668204.pdf I do not speak any chinese, but my question is more in a ...
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1answer
21 views

Setting prescaler for 8MHz external oscillator in Atmega2560

I am relatively new in Atmega MCU's (too used with graphical interfaces). I am using an external clock with 8MHz in my Atmega2560. My problem is that I cannot use UART communication with PIC18->...
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1answer
34 views

Is powering the Nuvoton N76E003 with just the UART0 pins legitimate?

I bought an 8 channel USB/UART controlled relay board from banggood.com: https://www.banggood.com/2-in-1-DC-5V-8Channel-USB-Serial-Port-Relay-Module-UART-RS232-TTL-Switch-Board-CH340-for-Windows-Linux-...
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1answer
53 views

Bridging Two UARTs on Same SBC

I recently started testing the UARTs on a RockpiE with the hardware v1.2 GPIO headers (https://wiki.radxa.com/RockpiE/hardware/gpio). In the 'boot/uEnv.txt' file, I disabled the console on uart2 by ...
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2answers
533 views

How can I make a UART receiver using logic devices (74164,counters,logic gates,..)?

I am trying to make a Serial-in Parallel-out Register to be controlled by my PC with logic gates and a 74164, 74193, 555 timer. I am programming it through visual basic and I have no problem making ...
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1answer
64 views

UART doesn't work with ADC enabled

I'm trying to send some data through UART using DMA. I'm also using DMA to control ADC and DAC. When ADC is enabled and I try to send data I get a HardFault error. The HardFault occurs exactly during ...
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1answer
50 views

PIC Curiosity HPC with multiple UARTs

I've got a Curiously HPC with two mikroBUS UART modules fitted (1x FTDI232R and 1x RS485 5V), however MCC in MPLAB X isn't letting me map the EUSART2 of the target (PIC18F46K40) to module 2, even ...
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3answers
57 views

ATMEGA resets c program when starting and stopping reading data from a PC

I'm sending data from an ATMEGA 328 to a PC and I have an incrementing line counter for each block of data I send. (4 integers) When I start and stop the receiving program on the PC, it resets the ...
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0answers
81 views

Level shifter problem

I have a question regarding a level shifter schematic that I've implemented. I need to connect a 1v8 logic UART device to both an arduino and a TTL232-3V3 cable. The Tx side works as expected and I ...
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1answer
33 views

Can you program Atmega32M1 with UART?

I have been reading datasheet over datasheet and seems to find nothing about this. I know I can use SPI_A for both bootloading and programming the atmega32m1. But can I use UART? And should I go with ...
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1answer
150 views

Teraterm to show hex data [closed]

I am getting UART data from micro-controller to PC. Micro-controller sends data in hex(eg.0x1B) format which can range from 0x00 to 0xFF. I want teraterm to display the received data in hex format. Is ...
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2answers
107 views

How does this YouTube video's author identify pins with multimeter?

I was watching this video on JTAG. It is mostly too difficult for me to follow, and I will likely learn more about UART first before returning to this. At around 13:00 he uses a multi-meter to ...
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1answer
180 views

Unable to display UART character data sent from STM32F407G Discovery Board (TX) to Ubuntu(or Raspian) on Rasperry Pi 3 Model B (RX)

Solved. The problem was a bad board & then appending extra "\n" in the output after reading from via "C". I'm trying to send data via UART from STM32F407G Discovery Board ...
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0answers
39 views

Adding activity indicator LED to 3.3V serial line using enhancement mosfet

I want to make a PCB with a STM32 MCU on it. I will only have a 3.3V supply rail for this PCB. I will be using UART for some communication (AFAIK it is ACTIVE LOW) and I am planning to have activity ...
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2answers
102 views

10m wired connection: I2C Repeater or RS485 [closed]

I need a wired connection between one Master and several (5-10) slave devices. I've considered UART, SPI, I2C, RS232 and RS485. In the end, I've narrowed down the options to I2C with a repeater or ...
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0answers
59 views

U1RXREG always returns NULL character

I am trying a UART loop back program using dsPIC33EV32GM104 IC. I created a project using Microchip code configurated. I assigned the TX pin as RC1 and RX pin as RB4. Baud rate setting is 9600, 8 data ...
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1answer
56 views

What to consider when choosing a crystal

I'm working on a Datalogger project power by a battery that needs to take sensor measurements and broadcast the parameters to a server. The power source to the CPU is 3.3Vcc from the battery. The ...
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2answers
46 views

Best approach to share/switch UART between multiple interfaces?

I'm building a board where I want to support multiple types of interfaces like RS422/RS485, CAN Bus, RS232 and connect these to my MCU using UART. If I only have one free UART on the MCU, what is the ...
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1answer
224 views

Differences between UART receiver STOP bit implementations

Some UART receivers require that the specified number of stop bits are present in the received data. For example, if the receiving UART is configured for 2 stop bits, the transmitting UART must also ...
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0answers
27 views

atmega328p UART rx pin

I have simple co2 meter using atmega328p as uC (Arduino mini Pro board actually). Microcontroller is sending measurements over FT232RL to a PC host (one way communication from AVR to PC), but this ...
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0answers
47 views

Connecting RS232 GPS Board to Raspberry Pi

I purchased a NEO-6M GPS board to connect to my Raspberry Pi, and when I bought it I didn't realize that it was meant for RS-232 communication instead of UART TTL (which I believe is what the ...
0
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1answer
83 views

Why don't I need device drivers for a UART to communicate with a Linux box but need device drivers if USB is to be used for communication? [closed]

I have a Linux box. I want to troubleshoot certain things and I was told that I need to custom solder pins to communicate using UART as perhaps it doesnt have device drivers to communicate using a ...
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3answers
127 views

Send Data With Usart STM32

I have to send data using the usart2 in my nucleo64 stm32f446re board. The type of data I have to send is float but until now I always send uint8_t using this code; ...
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2answers
69 views

STM32 UART send broken frames

I have a NUCLEO-F303RE board and try to send some data by one-wire UART with 57600 baudrate. But frames are sent broken (see images below): How must to be: What I get: I've tried to use different ...
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2answers
48 views

UART clock into receiver and transmitter

So below is a receiver diagram taken from: https://people.ece.cornell.edu/land/courses/ece4760/PIC32/Microchip_stuff/Ref_Manual/section_21_UART.pdf I can see that there is a clock "BAUD rate ...
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3answers
78 views

How to determine the end of transmission UART?

How does UARt determine the end of transmission of a series of bits? The single stop bit could be apart of the transfer data? How does UARt know the previous 1's were not the end of transmission?
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1answer
30 views

UART doesn't transmit all characters when using UDREn interrupt

Note: I am beginner :) MCU: Atemega328p In Method 1, I am using a UDRn data register empty interrupt once the transmit buffer is empty and inputting characters from ...
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0answers
47 views

Value XX In the testbench

Thanks for considering and spending your time. I'm trying to simulate UART VHDL code that I have written (which is not complete yet), but in the testbench I see XX value for the signal rx_data_out. I ...
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2answers
90 views

Receiving additional garbage data (for some characters) from STM32F103C8T6 (blue pill) UART1

I am learning bare metal embedded development using CMSIS Core framework. The problem I am facing is with UART communication. I am getting additional garbage value along with the character I am ...

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