Questions tagged [serial]

Serial communication is the standard USB connection between the Arduino and a computer with a standard USB A to B cable or through the TX/RX pins using a USB to serial converter. It can also refer to the serial library.

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Odd characters in serial monitor

I have been recently working on a website that takes input from the arduino ie- temperature and humidity. But there is a fatal problem that I've encountered, the serial monitor spews out some garbage ...
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how to change the values for timing variables (A, B, C) using serial monitor and keyboard [closed]

use a computer keyboard’s numbers to select the variable (eg variable A,B,C) you want to change, press “Enter”, and then type the new value and press “Enter”. You should be able to type “exit” to ...
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CRC8 code not working properly

I need to send a string followed by its CRC8, 0x31 polynomial (= X^8 + X^5 + X^4 + 1), I've coded this successfully after some troubles, but it doesn't seem to work properly when I check the results. ...
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How to transfer a data file from Arduino to a computer over USB connection

I have a project logging sensor values to an SD card. I want to transmit the current file to a computer over USB. The current brain is a Feather M0 Adalogger. I guessed that accomplishing this ...
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Polling data serially from a controller using RPI Pico as an USB Host

I am currently working on a system where I have one controller which sends data serially ( through data+ and data- ). I am trying to poll this data using Raspberry Pi PICO 2040 in USB Host mode. I ...
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Arduino filling serial buffer with nulls

I just wrote some code that just sends a string from Arduino to Processing. Processing prints the string and displays the number of characters in the buffer... After uploading the sketch to the ...
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Can't upload sketch on arduino mega2560

I have a serious problem with my arduino mega2560. when i connect the arduino to my laptop, RX and TX leds doesn't blink at all. but pin13 led and power led works correctly and also Vcc and GND pins ...
3 votes
1 answer
107 views

I'm using nRF2401 and in my transmitter and receiver the Rx is not blinking and Tx is blinking; why does Rx not blink?

I did a search on the meaning of RX and TX and it seems TX means sending data and RX means receiving data. So when my transmitter is turned off, my receiver looks like this and it works with a battery:...
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Adding Serial2 ends up blocking nano rp2040

Background Info I want to have two serials in my arduino nano rp2040 connect, in order to be able to communicate using the following scheme. (μC is a microcontroller). μC1 <--> μC2 <--> ...
1 vote
1 answer
60 views

No GPS data Neo 6M DFRduino Nano

I checked several answers for same question but none of them help. I also changed the nano board and GPS module but without luck. I ran it outdoor. This post question had same issue except my date ...
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2 answers
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String() vs char for simple flow control

I am newbie in Arduino and writing a program where I want to control the flow by using Serial monitor input (PI controller). I've read that using String() although easier it is slower than using char. ...
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Cannot upload sketch to DFRduino nano

I previously succeed in uploading the code to DFRDuino Nano (Arduino Nano Compatible) (with wrong digital pins) but after changing pin I cannot upload it again. From the document, I changed back the ...
2 votes
1 answer
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What components can be connected to pins 0/1 (RX/TX) without preventing uploading of code?

For a robot project I am using an Arduino Uno, and am running out of pins. The simplest solution would be to use digital pins 0/1. I know this means that I won't be able to use Serial communication (...
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Can I use this approach so I can sniff both TX and RX signals using a Second arduino?

Based upon this answer I can hook up 2 arduinos like this: But AFAIK The main microcontroller uses an RS232 protocol and AtMegau16 (or ATMegau8) converts it into USB one emulating an FTDI chip. But ...
1 vote
1 answer
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How initialise and uninitialise serial based on the user's input?

In Summary. If the argument is true, I want to create a function that prints the necessary stuff into the serial. However, if its false serial is uninitialised and does not print anything, it only ...
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The RF 433MHz receiver code is working only when I reset the Arduino

I'm working on RF modules using Arduino but I observed the if statement is only running once and I need to reset the receiver every time to make it work with real-time changes in the transmitter. I ...
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1 answer
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Using ESP32 GPIO, Serial.printf(...) prints weird characters when input is larger than 12 characters

Learning C with the Freenove WSP32-WROVER starter kit and there's an issue I cannot find an answer to. Using the provided code to input some data with UART, it would seem to have a strange behavior ...
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1 answer
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Trouble connecting barcode scanner to ESP32 devkit using UART - fails to connect over serial

I'm having trouble connecting a SparkFun 2D Barcode Scanner Breakout (effectively a DE2120) to a 30-pin ESP32 dev kit v1 (marked ESP-WROOM-32) and running the SerialScan sample application for this ...
1 vote
2 answers
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Novice learning Serial.readString()

New to Arduino, getting into String variables and reading them from serial monitor. Basically what I'm trying to do is have the user input either red, green, yellow. Whichever String they enter the ...
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Arduino Serial to USB=>serial data issue

I am using Mega 2560 to receive serial data from another device but the data appears on the serial terminal are strange characters. then i connected my USB to serial cable (HL-340) to the device and ...
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1 answer
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Pro Micro COM port disappeared after upload

I uploaded a sketch to my Pro Micro and it stopped showing in serial ports. Other Arduinos show up just fine. I've tried to detect serial devices using pyserial and it's also not seeing anything. I've ...
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USB serial port no longer detected after successful upload

I successfully uploaded a sketch to my Arduino Micro using the USB serial port but if I try to change the sketch that port is not available. The sketch I uploaded on the Micro runs fine when I plug in ...
2 votes
1 answer
109 views

Using Arduino to read and write data to RS232 device

I have a micro turbojet engine (JetCat P100-RX) which is operated through an Electronic Control Unit (ECU). The ECU has a lot of information about the engine. I want to access that information and ...
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1 vote
1 answer
92 views

Garbage in serial monitor

I'm revisiting my Arduino stuff (I want to revive Teleinfo shield to monitor closely my power consumption). I just cannot get the thing to work (Teleinfo Shield + Uno Wifi). When trying to check what'...
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Can read Serial but cannot write - serial communication Arduino Mega 2560 clone

I am having issues using the following USB to UART module. I am using an Arduino 2560 clone. I have two connections with the Arduino: COM7 which consists of the given module, connected to the main ...
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2 answers
50 views

How to display only specific data in the serial monitoring?

I got the following data as shown in the figure from imu razor which is connected to Arduino Mega 2560 in the serial monitoring and I want to get only the data that starts with "#A-R= " Can ...
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2 votes
2 answers
103 views

Uploading sketch to multiple Arduinos connected in series

I'm currently working on a project where you essentially will have multiple Arduinos (1 Uno, multiple Nanos) daisy-chained, only connected through 2 digital pins and one wire for Serial communication (...
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2 votes
1 answer
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Mildly accurate oscilloscope using Arduino Uno R3

I'm trying to make a mildly accurate oscilloscope using Arduino Uno R3 and I've done some research on the best method to do so. First of all I need to measure the voltage with a rather high sampling ...
1 vote
1 answer
90 views

Error while uploading the sketch to Arduino UNO using CLI

I have connected my Arduino UNO through USB to Raspberry pi 3B. I am using CLI for editing, compiling and uploading sketches > arduino-cli upload --fqbn arduino:avr:uno cli-test. However, after ...
-1 votes
1 answer
207 views

SIM800L not responding to AT commands

I am using SIM800L module the module. I am new to GSM modules, so I've searched for the basic to use the GSM with the Arduino. this is my code. #include <SoftwareSerial.h> SoftwareSerial ...
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1 answer
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CH340G based USB to UART adapter - Pinouts - Can't find schematics

This is the board I will be referring to. There are different variations of it (with built in buttons etc.) but they all seem to be based on the CH340 chip. My problem is, that I do not know what the ...
0 votes
1 answer
102 views

USB-C to USB-C cable Arduino is not responding even not powered by this cable

Hi I want to connect arduino NANO to my laptop with Type-C (USB-C) ports (on below image left side [4] and other side 3). Now I bought a USB-C to USB-C cable, because it appeared to be the right tool, ...
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Externally powering Arduino while reading voltage off it via USB

I have an Arduino UNO R3 where I’ve set Pin 13 to “HIGH” (as shown here) and I’ve connected an LED to Pin 13 and GND which glows brightly using a USB attached to my MacBook Air providing (I think) 5V. ...
1 vote
1 answer
28 views

How to receive data from Xbee in AT mode on Arduino Nano

I need to print data on the Arduino serial monitor received from the Xbee in AT mode. I have searched on most forums and have not found anything on how to do this. I have my Xbee tx connected to ...
2 votes
1 answer
657 views

What is the default baud rate without calling Serial.begin?

I cannot find the answer from official document and also surprised no one asked the same question. What is the default baud rates if I didn't call Serial.begin?
3 votes
1 answer
238 views

Ubuntu Serial Port Briefly showing on arduino IDE

I am using a NodeMcu with Arduino IDE on Ubuntu. I have managed to upload the blink script and it work. Now, when i plug the nodemcu, the serial port /dev/ttyUSB0 is briefly available in the IDE. ...
1 vote
1 answer
443 views

Sending float values from Python to Arduino using Serial communication

I need to send an array of floating-point numbers from python to Arduino Mega. For that, I read many sources [this this this this this] this] and many more links for the same I referred. But unable to ...
2 votes
1 answer
115 views

How to use Sim7020_mini NB-IOT module

I bough Sim7020_mini module. I put IOT Sim card, and plug-in antenna, connect Rx,Tx into USB-TTL, then put supply into VIN (5 volt), LED power was lid on. Arduino Serial Monitor set into 115200, but ...
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Getting more Hz while working with 3 serial ports (IMU sensors)

im doing a university project where we use 2 IMU sensors and a SD card reader to save the data from sensors. As you will probably see from the code, we specify the sensor port we listen to, save data ...
1 vote
2 answers
323 views

Circular buffer implementation and Serial.print()

I am trying to implement the simplest circular buffer in Arduino. I think I am able to implement it because my push and pop functions do not return any errors. However, when I want to print the data ...
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1 vote
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Can no longer select a port in Arduino IDE on Linux?

I am trying to upload to my Elegoo Mega 2560. I previously had it set up properly with the board installed and selected and the port automatically detected. Now when I go to Tools and hover my mouse ...
1 vote
0 answers
625 views

rst cause:2, boot mode:(3,6) caused by pointer reference

I am experiencing an unusual issue with my code. I have a LOLIN WEMOS D1 mini Lite and I am using the Arduino IDE to upload the sketch. The version of the board is 3.0.2 for ESP8266. The problem is ...
1 vote
1 answer
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MAX30100 and ESP8266 NodeMCU Serial Errors

This is my final year project and for some reason, the max30100 sensor defaults to static values once the HTTP post request has been performed. #include <ESP8266WiFi.h> #include <...
1 vote
1 answer
51 views

Poor man's serial sniffer: reading Serial.print logs of an Arduino esp32 dev kit from another

(I use ESP32 dev kits with Arduino api.) My dev kit 1 is running my firmware; and I want to measure the current it draws, therefore I don't like to plug the USB in. As I need to read the logs from the ...
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35 views

Arduino's stuck on COM1 and Device Manager Crashing

I just added a few new arduinos, and they are all loading on COM1. Here are some of the strange behaviors: Three arduinos plugged in, and they are all on COM1. I've never seen multiple devices ...
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2 votes
2 answers
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How do I fix my code so that it reads text from the serial monitor?

I have created a code that should print out "Enter true to deactivate alarm" in the serial monitor, then store the user's answer and print "alarm off" if they enter true and "...
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Arduino Uno R3 not recognized by Arduino IDE on Ubuntu 21.04

Now I've been pulling my hair for two days over this one. I've tried everything. I've turned every stone, looked at every search result, and every Arduino Forums thread. The problem is that Arduino ...
-1 votes
1 answer
92 views

Send batch info to com port?

I'm trying yo get a .bat file to send my cpu data to the com port my arduino is on. I've tried multiple google results (including one from this site) and everything I found will just... erase all the ...
1 vote
1 answer
66 views

Unexpected character added to char buffer array in serial monitor only when SD card initialized

I'm getting an unexpected extra character added to the serial monitor print line only when I initialize an SD card in the code. Normal The code below gives me this expected result in the serial ...
1 vote
0 answers
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Why do I read my own transferred data during my RS485 serial comms?

I am writing a RS485 serial communication firmware for the ESP32 (the minimal code is at the end of the question you can paste it as an Arduino INO or in platformIO main.cpp file). It is quite simple: ...

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