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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292 views

LCD Pin Numbering vs I2C Controller Pin Numbering vs Sketch

I've been playing with an Arduino Uno, trying to get a 16x2 LCD screen to work with an I2C controller. I've got this LCD screen and this controller. And I've been trying to get the sketch below to ...
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1answer
918 views

I2C_Anything String / Char Array issues

I've been working with the lovely I2C_Anything.h (thanks to the great work and support from Nick over at http://www.gammon.com.au/forum/?id=10896&reply=9#reply9).. All working great, I was using ...
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2answers
46 views

Is it possible to specify a pin upon which the data sent over i2c can act?

A master will send fan speed values to the slave. The slave will then read the fan speed values and change the speed value for the relevant pwm pin. However I am not sure how I can tell the slave ...
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2answers
454 views

Switch MPU6050 to send SCL data through A4 and SDA through A5

I have this MPU6050, and like most of the other MPU6050s, it is set up for SCL to be attached to A4 and SDA to be attached to A5. I have this shield on my Arduino Uno, which is configured for ...
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1answer
728 views

I2C Master send reset command to the slave counter

My name is Gianni, I live in Olbia Sardinia Italy and I have some experience in electronics. For several years I have been passionate about Arduino. They are now engaged in a project to counter with ...
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1answer
371 views

Unexpected output form Serial.println

So I have a teensy and an arduino uno connected together via I2C, however some very odd behavior is occurring, when monitoring the serial connection for shorter data sent over I2C I receive the ...
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1answer
418 views

Arduino messing up as slave over I2C

I have an Arduino Mega2560 and a Raspberry Pi hooked up through I2C. The Pi is acting as the master, while the Arduino is the slave. While sending data over I2C, the int message gets messed up and ...
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1answer
422 views

pcDuino 3B Wire library errors

I recently purchased a pcDuino 3B and I am very pleased with the Board so far. I can use the preinstalled arduino IDE to program the board from the board and run programs. However, when I came to use ...
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2answers
623 views

How do I connect two slaves of same type in I2C?

I am not experienced about I2C communications, but I do happen to have two HMC5883L magnetometer modules that I wish to connect to a single arduino. It uses I2C protocol, and hence the slave device ...
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1answer
188 views

About arduino serial communication

I've used the arduino uno with the python serial library months ago and some packets got lost in the way. I've been searching about serial communication for arduino and I've been thinking that I could ...
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1answer
931 views

Best way to interact arduino and python

So, i've worked with the pySerial module for python, where I communicated with my arduino via serial. However, this module only works for 32bits and I would like to make my project work on both ...
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35 views

I2C communication between arduino and raspberry pi breaks under stress for unclear reasons. Why?

I am having a behavior I cannot explain while using arduino mega as a I2C slave for a raspberry pi master. I am showing here an idealised program that shows the issue. I experience pretty much the ...
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1answer
21 views

Reset I2C connection with arduino as slave

I am currently using I2C serial communications with arduino as slave and raspberry pi as the master. I am sending sensor data from arduino to raspberry pi. I need to reset the I2C connection once the ...
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25 views

Tamper Protected Access Control System with Stored Password and Smoke, Motion Alerting - Solution Not a Question [closed]

First of all this is not a question. I am adding this for people need same kind of a solution. Components Needed, Arduino UNO Arduino Nano MQ 135 Gas Sensor PIR Sensor 12V Alarm 3* LEDs (Green,Red ...
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26 views

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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1answer
43 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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1answer
25 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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21 views

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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1answer
30 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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1answer
35 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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0answers
152 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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1answer
29 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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1answer
24 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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1answer
58 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 | ...
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35 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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1answer
105 views

i2c Connection for MCP4725(Dac) with Esp8266 wemos d1 mini

------------ This question has been edited ------------ note: Dac and Adc is12bits my problem : I use two ESP. Using esp1, I read the Adc amount of the alternating signal (ECG) and send it to esp2 ...
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25 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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38 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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1answer
20 views

Wire SlaveReceiver : will the registered function in onRecieve interrupt/conflict with loop block?

I am currently researching on I2C, and I made a configuration that has MasterWriter that transmits data to a SlaveReceiver that will store the data received from Master, into an SD card, and then ...
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17 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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51 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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1answer
46 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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0answers
36 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
25 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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0answers
40 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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0answers
37 views

i2C master/slave Arduino uno Programming to run 2 motors at once off separate boards [duplicate]

I am attempting to run a master/slave receiver arduino using two arduino uno's. I'm synchronizing both Arduino to control 1 dc motor and 1 stepper motor at once which each of the Arduino UNO board ...
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47 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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0answers
103 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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0answers
40 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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1answer
39 views

Arduino help adding a second mpu 6050 sensor my working code

Background information: I currently have this arduino code that uses one mpu 6050 sensor to get angles in the x, y, and z directions and then display them to the user nicely. Code can be found here ...
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0answers
47 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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92 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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1answer
200 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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2answers
488 views

How to connect MPU9250 with NodeMCU using SPI or I2C Slave?

I want to connect 3 MPU9250 sensors, but since there is just one I2C bus, so there are another 2 sensors I want to connect through SPI. Library used - https://github.com/bolderflight/MPU9250/blob/...
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0answers
96 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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0answers
66 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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0answers
99 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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0answers
68 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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0answers
67 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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1answer
105 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 ...