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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32 views

ESP01 and Arduino - Serial port confusion

I'm trying to understand how to think about ESP01 devices and arduino connectivity I purchased one of the USB programmers from Ebay to program the ESP01 - this works nicely, I can see the ESP doing ...
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1answer
47 views

Arduino UARTS Auto addressing slaves

i'm using this serial topology to connect my Act ATmega328p (Arduino) slaves together to a master ESP32. They are in total 10 ATmega328p slaves and one master: With this type of wiring i'm sure that ...
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Hardware/software serial for HC-05

can anyone please tell me the whole difference between hardware and software serial for the HC-05. I read UART,USB cable, serial and I was like really confused so what is the difference and advantages ...
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1answer
48 views

Serial Read Data Loss With Arduino Nano

I am trying to use Serial reading from a python serial code (which is running on my Jetson Nano) in my project, but in some loop in my code, my data is receiving wrong. I use Serial.readBytesUntil() ...
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33 views

Can you program an ESP32 with an Arduino?

I've done it with an ESP-8266 but can't find any articles on how to do it with an ESP-32. I'm working with an ESP-32 on my own PCB, not a dev board. I exposed: 3V3 GND EN TX RX IO0 I'm pretty sure I ...
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30 views

Subscribing to Bluefruit LE Friend with ArduinoBLE not working

I've been using an Arduino Nano 33 BLE to communicate with my PC over the BlueFruit LE Friend's UART characteristic. Using the default ArduinoBLE library, I'm able to connect to the BlueFruit from the ...
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1answer
62 views

NodeMCU v2 with MH-Z19B CO2 sensor UART read problem

I'm trying to read data from MH-Z19B sensor to NodeMCU v2 board with a simple circuit like this. Some key points, which could be not that obvious from picture: - sensor has separate power supply of ...
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1answer
17 views

Problem communicating with GSM module which is a Fona 3G from adafruit

My issue is fairly simple to describe but I have no idea what the problem could be. So I got my FONA 3G and immediately after taking it out of the box, I connected the battery and I wired up my FTDI ...
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15 views

Does MFRC522 module read all 13.56 MHz RFID tags?

Hello everyone. Does MFRC522 module read all 13.56 MHz RFID tags? Or there are different types of the 13.56 MHz tags that the MFRC522 module reads only one type of them?
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110 views

How can i read and write the data from a Delta plc-s series through Arduino UNO?

I am trying to communicate PLC with arduino through rs232 as well rs 485. But, I am not able to read and write data. I can observe the data in PLC through ladder logic but not in arduino. I am trying ...
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21 views

Receive SMS using Arduino Nano and Quectel EC25

I'm trying to use an Arduino Nano to communicate with a Quectel EC25 module from this Raspberry Pi 4G HAT. I'm using Arduino's pins 8 and 7 to communicate with RX and TX from the Quectel module. I'm ...
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2answers
215 views

Binary to decimal using bitwise operators

I am trying to convert some binary data to decimal numbers. I succeeded to convert binary to hex, but now I want to do the same with binary to decimal. I want to use bitwise operators and NO array. ...
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1answer
60 views

Will a pull up resistor help the UART transmission accuracy on Arduino nano?

On A post from Arduino forum , someone mentioned that a pull up resistor over RX/TX pin could help the reliably of UART communication. Is that really the case for nano and uno board?
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56 views

How to use any module that has no library for arduino?

I am 2 years old in this Arduino world. I am currently working on a project where I am about to make use of a fingerprint sensor. Now my question is that could we be able to make use of a sensor that ...
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49 views

Is Arduino Mega useing one buffer or multiple buffers?

So Arduino Mega has Serial, Serial1, Serial2, Serial3. However, does those Serial lines use the same buffer? or four independent ones? i.e. are they truly receive single independently, or actually ...
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42 views

Super fast UART transimission return error

The code was based on Fahad Mirza's very helpful example here Send structure through Serial The Sender's code now became struct Gyro_data_structure { char command_name[5]; float gyro_X; float ...
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237 views

Send structure through Serial

Suppose that one defined a data structure and wanted to send it through serial. struct Gyro_data_structure { char command_name[5]; float gyro_X; float gyro_Y; float gyro_Z; }; ...
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4answers
209 views

If Arduino connected to computer and opened up Serial Monitor, will Tx and Rx pin still be working?

Suppose one connected two of the Arduino Uno boards through Rx and Tx pins. Then, if one or both of the Arduino boards were connected to computer, and possibly opened up Serial Monitors, will Tx and ...
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1answer
51 views

How to set a time out like Serial.setTimeout() for Serial.read()?

I read a comment form here: "Serial.setTimeout() sets the maximum milliseconds to wait for serial data when using Serial.readBytesUntil(), Serial.readBytes(), Serial.parseInt() or Serial.parseFloat()...
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603 views

ESP32 Hardware Serial Flow control and full espressif/arduino-esp32 support

I have a similar issue. I want to use the ESP32 with RS485. I have used the Arduino and this works well assigning pins, but it seems not to allow full use of the UART. I see the new uarts in the ...
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55 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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2answers
115 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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1answer
36 views

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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1answer
447 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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167 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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1answer
46 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
26 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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1answer
88 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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2answers
131 views

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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90 views

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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1answer
248 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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52 views

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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100 views

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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1answer
218 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
265 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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127 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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1answer
375 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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93 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
47 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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1k 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
3k 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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46 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
317 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
334 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
154 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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86 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
80 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
96 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
385 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
836 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 ...