Questions tagged [uart]

A UART is a Universal Asynchronous Receiver/Transmitter. This refers to the "hardware" serial port in the processor. Use this tag for questions about hardware serial.

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48 views

Monitor serial0 while code is being uploaded

I'm trying to upload the sketch on a Mega 2560 via the serial port 0 using another microcontroller. To better undestand the process, I decided to first observe what avrdude is doing while it is ...
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60 views

UART communication - Serial is always empty

I have a payment terminal which uses UART (or simply speaking Rx, Tx, Gnd pins) and I have an Android tablet app which is connected to the terminal using USB to DB9 adapter based on PL2303 chip. The ...
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Arduino ESP8266 communication

I saw two peculiar things while googling this subjects. Sometimes Tx and Rx are connected directly despite the fact, that it works on different voltages, sometimes resistor dividor is used, sometimes ...
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116 views

HLW8032 UART sends random data ( Registers Overflow often)

I designed my own version of smart socket just like the Sonoff with power metering chip HLW8032. And when I read the data in ESP-12F the data doesn't have a fixed format. To troubleshoot the issue, I ...
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30 views

Arduino Nano and neoSWserial library

So I've been playing with neoSWserial library on Arduino Nano. I've been using the example interrupt code: #include <NeoSWSerial.h> NeoSWSerial ss( 4, 3 ); volatile uint32_t newlines = 0UL; ...
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37 views

Understanding datasheet of a HCHO gas sensor

I have a gas sensor whose datasheet is attached: DS-HCHO Now it says that UART communication is needed (P2P) where it (module) waits for Data Frame before tx the data frame to host which I need. ...
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1answer
19 views

Can I disable the TX pin by setting its mode to INPUT while still receiving data on the RX pin of a UART?

I'm using the ATmega328PB in a personal project with MiniCore. My board streams data in on the RX pin from another microcontroller, but my board also has a DIP switch connected to the TX pin, that's ...
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29 views

Use Arduino as transmitter and receiver UART

I know UART and serial communication model and data frame. But I want to ask about something else, when I searched in internet just found examples of one Arduino as (receiver) and another Arduino as (...
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Arduino Mega reading same information that it's sending out via serial

So I have an Arduino Mega and I'm attempting serial communication with another device, and I ran into this weird issue. Let's say I use Serial1.write to send out hex A-F. If I read on that same port (...
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Can I use an UART RS485 board with DMX simple library?

I want to use DMX512, and found a library DmxSimple, which uses a single (non UART) GPIO pin as output (see DmxSimple.wiki. I currently use a TTL RS485 board, which does not have any TVS/polyfused ...
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85 views

atmega328: external crystal oscillator and uart

I need an clearity about external crystal oscilator. I got communication between esp32 and atmega8/88/328 processor, I use atmega wih internal oscillator and looks like it have problem with serial ...
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MEGA2560 only starts program after pressing RESET button multiple times

I am working on a program where I am controlling an MP3 player by using UART between my MEGA2560 and the MP3 player. The MEGA2560 sends serial commands to the MP3 player when external interrupts are ...
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how to name master and slave with UART and Serial event

I am trying to implement some small program using below code, now this code works fine and I'm getting data to the slave. But I have more than one slave, so now I'm not sure how to send the Address of ...
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93 views

Arduino Hardware serial pins with RS485

I tried asking a question in my earlier post - SerialEvent with RS485 communication it helped me understand Hardware serial and Software serial but i had few more questions for which i started this ...
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1answer
76 views

I want my arduino mega to read from all 4 serial ports at the same time, running sequentially through each one

I currently have the code running through Serial1, which works exactly as I want it to: int RFIDResetPin = 13; void setup() { Serial.begin(9600); Serial1.begin(9600); Serial2.begin(9600); ...
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60 views

Nodemcu ESP12-E (ESP8266), Can I reprogramming when the UART pins are defined as GPIO?

I wonder if there may be any problems using the pins that the UART are using as GPIOs, if now I want to be able to reprogram the circuit? (Of course I will detach the ESP12-E from the mainboard before ...
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139 views

Can't connect to my ESP32 board via serial

I'm completely new to electronics work. Today I've received the ESP32 board that I ordered. (It's a WROOM-32.) I followed the instructions here. I connected the board to my computer via USB and I ...
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48 views

Reading incoming/outgoing bytes from SIM card / ATR

I am trying to read data from a two-way I/O uart pin of a sim card on Arduino. It is attached to the GPRS Arduino shield (with SIM900 modem). I believe I have a baud rate issue. I am supposed to ...
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1answer
34 views

Which pins are represented by these constants from ABR library?

The following code comes from AtTiny serial library that I want to use: #include <avr/io.h> #include <avr/interrupt.h> #include <util/delay.h> // change these to use another pin #...
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467 views

Using 2 serial ports on NodeMCU

I am using a NodeMCU ESP 12E board which will be programmed using the Arduino IDE. I intend to use it to send GPS data to the Blynk app server. I also want to interface a Bluetooth module HC-05 to the ...
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1answer
1k views

How to use Serial.setTimeout()

I am just playing with the UART interface of my board to learn about how it works. Since I have only one board, I send data out just to receive them by my own board, which is working so far. Now I ...
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25 views

PLC with Arduino UNO [duplicate]

In my current project I have to communicate with 10 different devices with PLC. PLC is the master. When input comes from PLC to a device, the Arduino controller through RS485, I want to check the ...
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1answer
104 views

Program Arduino via UART from ESP8266 SPIFFS

I have built a custom board that has an ATmega328p connected to an ESP8266 module via UART. I am currently programming the ATmega328p using a USBtiny programmer via an SPI header. The ESP8266 module ...
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1answer
262 views

How to chose softserial library use on Arduino project?

I want to do a project that has multiple Arduino communication through UART, that project project one of limit is using Arduino Nano (small and cheap). I need to set 4 serial port instance on Nano to ...
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1answer
80 views

Sending data to UART using Atmel Studio with Attiny84

I want to send data to TFDI. It can be hello world or any value of variable. But I can't do. I haven't found example code on the internet. Some examples doesn't work. I am using Atmel Studio.
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64 views

Wait between UART frames

I have to reproduce a signal (of 6 UART frames) which have 950 µs delay between each of the frames. Than, a delay of 37ms at the end of those frames. Everything going right except the delay between ...
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2answers
59 views

Accessing multiplexed I2C and UART pins of STM32F103 in arduino IDE

I want to access both of the multiplexed I2C and UART pins in the same program. I am programming in Arduino IDE.Can anyone please tell me how to access same pins for different functionalities?
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1answer
63 views

toggling Rx, Tx pins after Serial.begin

What should one expect when the following program runs on Arduino Uno? void setup() { Serial.begin(9600); DDRD |= 0b11; } void loop() { PORTD |= 0b11; delay(100); Serial.print("...
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3answers
291 views

Control I2C relay board from two Arduino Uno

how can I make multi master Arduino device to work with single I2C device? As both the master device are 20 m away from Slave device, I am using the I2C relay board to connect with 2 Arduino boards ...
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1answer
396 views

Preforming impedance termination for UART Communication (TX and RX) pins

I need two Arduino devices (Arduino Mega and Nano) to communicate with each other via UART. The two Arduino devices are long distance apart from each other. The distance is 1.5 meters. The Arduino 1 ...
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1answer
319 views

Multiple sensors connected to Arduino MEGA 2560 Serial ports

I am using Arduino MEGA 2560 to read values from two sensors. Sensor 1 is providing us two values separated by a comma and a space followed by a newline character. e.g.: 2.277, 7.942 2.269, 7.897 2....
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195 views

Baud rate of Arduinos bootloader

I am learning UART and the problem that i have is understanding what happens when i send serial data to my PC via USB which is built in to the Arduino uno board. For incoming serial data i am using ...
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1answer
623 views

UART connection between Arduino Nano and NodeMCU

I'm trying to create an UART connection between a Nano and an NodeMCU, running MicroPython. Code for trying is meaningless - Arduino says "HI", and ESP8266 should receive and print msg value. ...
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1answer
119 views

USART, SPI or Bit-Bang for the continuous transfer of bytes without inserted extra bits

I have heard that The SPI hardware introduces a 9th, HIGH bit between bytes USART still uses start and stop bits when in synchronous mode Are both these statements true? Can I modify the built-in ...
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1answer
182 views

Serial Communication - strtok() issue

I'm working on UART communication between an ESP32 (sender) and ESP8266 NodeMCU board(receiver). The host is sending out the following character string: Serial.println("2753192144$1&"); The ...
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1k views

Arduino UART (TX/RX) multidrop 1 master 50 slaves

I'm thinking to connect about 50 slave Arduinos on 1 master using TX/RX. I'm following recommendation of these links: I'm looking for a way to serially communicate with a multi mesh Arduino slave ...
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1answer
1k views

How to work with non-traditional UART baud rates

I am trying, unsuccessfully to communicate, using my Arduino Nano, with a custom device at a baud rate of 800 kbit/s. The Arduino code look like this: void setup() { // Put your setup code ...
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2answers
344 views

Double Speed Operation for USART on Arduino Mega 2560

I happened to be looking through the HardwareSerial.cpp file that contains the functions used for Serial communication for Arduino. While looking through the HardwareSerial::begin(baud, config) ...
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89 views

How to run Arduino code on Linux? [closed]

I want to use an MFRC522 module as explained in this video. But is it possible to get around with Arduino and use a TTL to USB converter to connect RC522 directly to my PC running Ubuntu? Using the ...
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1answer
131 views

How to stop sending the last received char of UART echo function?

I developed a code for uart based ISR with linear buffers, the problem is that it keep sending the last received char in Arduino IDE. Here's the application code: #include "uart_new.h" void setup() ...
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1answer
136 views

Arduino Mega Pins for SoftwareSerial (vs. AltSoftSerial)

I am currently looking at using an Arduino Mega to build a MIDI Receive box that will then pump the data over USB, but am having design issues/uncertainties with the Arduino's receiving end. I am ...
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2answers
3k views

how to send data to Adafruit Bluefruit Feather (32u4) over bluetooth?

Sup yo. I have my Adafruit Bluefruit Feather all wired up. It's lovely. I've got it responding to commands over the USB serial, activating an array of octocouplers. It's terrific. Here's the ...
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1answer
101 views

UART communication, is it possible to use only the TX line?

I am trying to connect an ESP-01 with an ArduinoMega through the serial port of both, as they use different voltage levels I would need a voltage divider between the TX pin of the Mega (pin 1) and the ...
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2answers
2k views

Is it possible to extract a hex file via UART from an Arduino?

Right now I am tinkering on my 3D printer that has an Arduino mega as a brain. I need to update the Marlin firmware but in case of an error I want to create an backup of the firmware. And because it ...
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2answers
3k views

Connect ESP-01 to USB Uart

for programming my ESP-01 chip I bought an "USB Uart", but it looks different to all the ones in all tutorials. I don't know how to connect the uart to the esp. The uart i bought has following pins: ...
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2answers
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Serial communication between multiple devices (or Arduinos)

What I know from my search on the internet, for both SPI and I2C protocols, communication between multiple devices needs a master, which initiates the communication, and slaves, which respond to the ...
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1answer
290 views

Alternative to UART/I2C LCD displays?

I'm building a MIDI synthesizer on Arduino Uno, and am considering user interface options. I see on Adafruit and Sparkfun there are 16x2 LCD panels available that interface via I2C serial or by UART,...
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318 views

ATMega328 to Arduino Mega Serial Communication

I'm working with an ATMEGA328 chip on a breadboard. I'm using the Arduino library for easy coding within Atmel Studio (and an ISP MKii for programming). I have no way to easily debug my code, so I ...
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1answer
1k views

Why these specific voltage divider resisters needed for Arduino Uno RX TX pins?

I have an Arduino Uno attached to a Parallax Boe-Bot shield, and plugged into the shield breadboard, the Parallax WX ESP8266 Wi-Fi SIP. When I attach the DO/DI pins of the ESP8266 board to the RX/TX ...
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1answer
529 views

Can't get call / message from A7 gsm+gprs+gps module

I am making a project using arduino uno & A7 gsm+gps+gprs module.my circuit connection is like this: A7 UTXD -> arduino RX A7 RTXD -> arduino TX A7 GND -> arduino GND A7 pwr_key -> A7 ...