Questions tagged [i2c]

Inter-Integrated Circuit (I²C) is a bus for low speed peripherals. Use this tag for questions regarding how to use I²C with an Arduino, or for problems with I²C and your Arduino.

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Emulate I2C BMP180

I want to know if possible to emulate a temp sensor such as BMP180 with Arduino. The reason I am asking this is : BMP 180 is obsolete, so I am trying to replace it with BMP280 I want to read the ...
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65 views

How do you write to a specific register using I2C communcation?

I am trying to write to a charging IC (BQ24193) and I am trying to figure out how to use I2C to write to a specific register so I can set up the charging IC properly. I have watched a few videos on ...
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59 views

qMenuSystem Oled I2C can't make it work

I'm trying to make the qMenuSystem to work with my I2C Monochrome OLED display but without any luck. To summarize all here's what's with it : - the qMenuSystem is using a library called : ...
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Why is I2C OLED failing to initialise when SPI device is added to project (SD.h causing issue)? [duplicate]

My project uses an RTC, GY-521 MPU-6050 3-Axis Gyro and MakerHawk OLED Display Module. All working fine together to show current date and time as well as displaying Acceleration on 3 Axis. I now want ...
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43 views

Slave to Send Data after Receiving Command using I2C

I want to have my Slave Arduino to send signal to Master after the command was made. But the Slave Arduino does not proceeds to sending the signal after doing the command. What is wrong with my code? ...
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48 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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1k views

Using ESP32-CAM (with ov2640 camera image sensor) to send image via USB

I was trying to obtain image from ESP32-CAM (with ov2640 camera image sensor). I obtained the image through camera web server by connecting the ESP32-CAM and PC to same wifi network. A USB to TTL ...
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49 views

Two arduino boards with sensors i2c

I am new and lost I have been searching the internet about how to transfer data of multiple sensors from one Arduino to another using i2c but no luck. all the codes and tutorials online focus on ...
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87 views

Setting up I2C with HTU21D, no response after beginTransmission

I'm playing with the temperature/humidity sensor HTU21D. Datasheet: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Data+Sheet%7FHPC199_6%7FA6%7Fpdf%7FEnglish%...
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84 views

Communication with sensor KMX63 in I2C

I trying to use a new sensor the KMX63 with a Arduino Uno board, my sensor is on a evaluation board made by kionix. For the connexion il linked as follows: | Pin Uno | Pin evaluation board | | A5 | 5 |...
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65 views

I2C freeze on master

On my first big Arduino-project I made a game using the following Arduino's and the I2C-protocol: 1x Mega as master 4x Mega as slave 2x Uno as slave The Arduino's controll a physical game where the ...
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43 views

NFC wont send URL to mobile phone

I'm using nfc 2 click (NT3H2111), I tried via arduino to send data to my mobile phone using this code : #include <Wire.h> int i = 0; int j = 0; uint8_t NDEF_DATA[] = { 0x03, // NDEF Message ...
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70 views

Servo PWM Pin seems to be interfering with Wire.onRequest i2C function

A newbie here. I am thinking of interfacing Raspberry Pi with Arduino via I2c to control a few servo motor (as RPi have limited PWM pins). Meaning I would send input from RPi to Arduino to allow to ...
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24 views

Arduino Setup for RF Transmit and Receive, IR Receive, WS2812 LEDs and a Piezo Speaker

I am new to Arduino and microcontroller in general and just finished one Project (TonUINO - a DIY music box for kids). Now I am planing and working on my next project. A IR shooting range. The guns ...
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101 views

Calculate pullup resistor, cat5e ftp

let me describe my schema, i got one arduino and one esp32 connected over i2c using 30m cat 5e ftp cable, I'm using 12v to power up both devices, each of them have dc-dc converter that convert to 5V, ...
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174 views

Does LabVIEW Linx affect the communication speed with Arduino?

I am using LabVIEW to connect to Arduino Mega. I control a logic gate to switch the current On/Off and at the same time there is an I2C connection with a sensor. It came to my attention that the ...
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61 views

Arduino 3.5" TFT Display going blank after sending data through I2C

I'm trying to use I2C to send and receive commands between an Arduino UNO R3 and an Arduino Mega R3, with a 3.5" TFT display connected to the Mega. I have verified that my display is fully functional ...
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1answer
36 views

Trouble with i2c on ESP8266

I have used with partial success I2C with the ESP8266. When it works, it works well, with many devices on the bus. I've examined the signals on a 'scope to assure Vlo, Vhi, Tr, and Tf. However, ...
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84 views

I2C between two arduinos

I have 4 gyro sensors that communicate to arduino uno using I2C and then arduino uno sends the data to arduino mega. I was wondering if I could use i2c for this purpose or if I should look for other ...
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64 views

Lost with Nano and i2c

I've been struggling with some code that was failing to "begin()" any devices on my i2c bus. I've uploaded a scanner program from arduino playground which lists the addresses of any i2c modules found. ...
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388 views

i2c code hanging - tried all connections

I'm trying to connect a TCA9548a breakout to my nano (also tried using an uno), but it can't recognise it - using the i2c scanner it just hangs on 'scanning...' I've tried everything suggested in ...
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86 views

Arduino IDE + Metro + I2C device (Grideye) + Code for Uno = weird results?

I have been working successfully with the arduino uno and a thermal camera device called grid eye. There is a board available at the popular suppliers of arduino addons. For the uno, the code looks ...
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80 views

Having trouble reading directly from VEML6075 UV sensor from its registers(I2C)

I'm kinda new to Arduino and decided to dive deeper into learning abit more about Arduino; So i decided to grab a Sparkfun VEML6075 UV sensor and try to: 1) Initialise it 2) Take readings from it ...
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345 views

LCD not displaying any character with I2C or when used separately

I have an arduino uno and pin connection for I2C are - SDA --> A4 SCL --> A5 VCC --> 5v GND --> GND This the code i am uploading taken from the examples - #include <Wire.h> #...
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367 views

Possible to connect 3 MPU9250 to Node MCU without multiplixer?

Is the idea of connecting AD0 pins of MPU9250 is still valid like the 2nd answer of this question? - How to change i2c address for mpu9250? I have connected 2 sensor as test. SCL & SDA of both ...
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161 views

How to interface Arduino with NXP PCA8561 LCD segment driver?

I've just bought few NXP PCA8561AHN LCD segment drivers to do some tests which unfortunately did not went as expected. I'm familiar with expanders and segment LED displays but LCDs seem to be way ...
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106 views

SerializeJson not working when using softserial

IDE:1.8.8 Board:Arduino UNO When I use the code below, I get result of print like this. { "result": [ { "ID": "01", "Value": [ "2", "1", "13" ] } ] } But when I use SoftwareSerial and in the setup ...
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310 views

What is the difference between the digital temperature sensors SHT31 and DHT11 or DHT12?

I am looking for a digital temperature sensor with I2C interface. I found the SHT31 and the DHT12 (compatible to DHT11). Both also include humidity sensors. And I found libraries for both of them. ...
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93 views

Problem I²C Communication between Arduinos

My Problem seems to be that my I²C slave randomly disconnects. I have an Arduino Due communicating with a Arduino Chestnut board (bought hardware). I now measure data with the Due and then send the ...
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137 views

Buffer to string

I'm a bit of a noob, so excuse if this is more obvious to me than to you. I want to convert a u16 to a string. The u16 is the data coming in from the sensor. I need it as a string, or anything else ...
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201 views

Same output on displays with different I2C-addresses (AdaFruit library, ESP32)

I've got two displays hooked up to a ESP32 via I2C and I'm using the AdaFruit library. All handling display output is packed in a own library. As I was testing I only had one display set up and ...
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109 views

Bit Bang I2C with port manipulation on AtTiny84: new pinout doesn't work

So I am trying to understand bit banging and port operations. I'm developing a breakout board with an ADXL343 IMU read by an AtTiny44 via i2c. I adapted this code from MIT's How To Make Almost ...
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296 views

LCD displays weird characters

I have connected the LCD by the 3 wire method using the LiquidCrystal595 library+74HC595 register shift; sometimes "hello world" is displayed but other times the LCD displays weird characters. How to ...
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127 views

Using TCA9548A to read 30 ADCs

I want to read 30 differential ended analog sensors. Using ADS1115 16 bit this is possible, but we end up having only 4 address on I2C, so i chose TCA9548A breakout board with 8 I2C multiplex channels,...
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330 views

LCD (I2C) issues with pull up resistor

I'm close to finish my first DYI project. But a never seen issue on the breadboard has apprear as soon as assembled. The LCD is always / totally blank/black. When I remove the 4.7 K ohm pull-up ...
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257 views

Why is Wire.endTransmission(true) returning 10?

Question: The follow code is printing 10 over and over again (with spaces in between). I have an I2C device connected at 0x60, and nothing connected at 0x61. I'm confused by this because the Wire....
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118 views

Teensy freezing when reading ir sensor

I have a teensy that controls a motor and reads from a ir sensor, GP2Y0E02b. The issue i run into is that at random times the teensy seems to freeze, the main code stops printing but the interrupt ...
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97 views

Arduno as bridge between two i2c masters

so I am gonna just jump right into the topic. Recently, I have been trying to build a project where I need to connect an ev3 to a raspberry pi. I have decided doing it by i2c after reading (and ...
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1answer
86 views

Decreasing a functions programming size

I have Arduino Code that utilizes the I2CDev library to control an MPU-6050. I am pretty new to coding and copied and pasted most of the code from examples I have found around. I am starting to run ...
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2answers
351 views

Share I2C pins with other device when lacking GPIOs

We're Using ESP12E as our MCU and we have three functionality : SIM800 connected to TX(GPIO1), RX(GPIO3) Matrix Keypad connected to GPIOs: 14,13,2,10,0,4,5,16 GLCD connected to GPIOs: 15,12 And we ...
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216 views

how to send FFT array consist of 512 Samples Data From arduino to raspberry pi using i2c and this is the code for FFT any Suggestion plz?

#include "arduinoFFT.h" float y, x = 0; #define t PE_0 #define SAMPLES 1024 //Must be a power of 2 #define SAMPLING_FREQUENCY 1024 //Hz, must be less than 10000 due to ADC arduinoFFT FFT = ...
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1answer
862 views

How can I send and receive data from an Arduino Uno to Arduino Mega using I2C?

I am trying to send data as a string from an Arduino Uno to another Arduino Mega. I have read about the I2C connection where we connect the RX to TX oppositely. How to start and send and receive ...
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204 views

Problem using Optiga Trust X I2C

Did someone ever used the Infineon Optiga Trust X module with Arduino using any I2C library ? Here is the technical documentation of the Trust X module. I'm trying to get the I2C_STATE register data ...
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7k views

NodeMCU (ESP8266) with SPI TFT, I2C RTC, & 2 Buttons, correct GPIO to use?

From all my research it seems that the NodeMCU only has 11 available GPIO (6-11 are used to connect flash memory chip), i'm wondering if anybody can help me with these final connections I have left ...
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200 views

Using 4 identical sensors on the I2C bus

I am using 4 Pololu VL6180X ToF sensors on the Arduino UNO for a school project but just can't seem to get it working correctly. I understand that I need to hold them in reset and change the I2C ...
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677 views

trouble running i2c and spi at the same time

I know this question has been asked before but I am having trouble running I2c and SPI at the same time. I am attaching my code below. The problem when I run the code is that the LED's don't blink ...
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1answer
48 views

Steppers only vibrate, not rotate with I2C

The goal of my project is to be able to control two steppers with 4 buttons. Steppers are connected to Adafruit Motor shield(the older one) which is stacked on Arduino UNO, buttons are connected to ...
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494 views

Arduino Pro Mini (5v) I2C pullups

I recently bought an ESP-WROOM-32 module and I want it to talk to my Pro Mini via I2C. Do I have to pull-up the lines to the 3.3v side (ESP32)? Since the Pro Mini runs at 5v, I think it's a bad idea ...
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619 views

LSM9DS1: Inconsistent data from an accelerometer

I'm currently getting inconsistent data from the accelerometer of my Adafruit LSM9DS1. To be more precise I either get a value close to the correct gravity (eg. 9.496515) or some reading like it was ...
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393 views

Arduino SPI and I2C Combo [duplicate]

We are trying to communicate between 2 Arduino's (1 Nano and 1 Mega) and a Raspberry Pi. This communication works till we add an SPI Connection to our RFID Scanner (RC522). We ran into the problem ...

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