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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245 views

Common/standard library and/or protocol for Arduino to be I2C slave for driving NeoPixel

I would like to control a string of WS2812/NeoPixels from a SBC like a BeagleBone or C.H.I.P. I realize someone has gone through the trouble to come up with a way to drive the WS2812 string from a ...
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1answer
537 views

How to make PCA9685 work with Arduino Due?

I have Arduino Due and PCA9685. I use this library: https://github.com/adafruit/Adafruit-PWM-Servo-Driver-Library The board does not do anything with servo connected. I tried to use SDA/SCL pins and ...
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0answers
64 views

Inexpensive way of connecting a lot of modules on a distance

I need to connect a lot (~100) of modules with a computer (Raspberry pi). The modules are based on Arduino micro and are very simple. They will be spread around, but for the two adjacent the distance ...
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2answers
647 views

I2C communication between 2 Arduinos with updated wire library

I would like to enable communication between two Arduino 101. From what I have read, the best method is to use I2C using the wire library. However, it seems as though the newest Arduino IDE has an ...
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1answer
45 views

Accelerometer Z Value off a significant amount, all other values reasonable

I'm using the MPU9255 Accelerometer to measure acceleration in the X,Y, and Z directions. As per the datasheet, I've applied a scaling to the raw digital values based off of whether I specified +- 2G,...
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1answer
760 views

ADXL345 I2C setup not returning anything

My hookup is like this: GND - GND VCC - 5V CS - 5V SDO - GND SDA - A4 SCL - A5 Here is the code: #include <Wire.h> #include <ADXL345.h> ADXL345 accelerometer; void setup(void) { ...
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2answers
638 views

I2C multi sensors reading on Arduino

I have several sensors (Grove multichannel gas sensor, Air Pressure Sensor MPX4115A, Temperature and Humidity Sensor DHT11) where most of them uses I2C communication. I wonder if it is possible to ...
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1answer
4k views

esp8266-01 and arduino UNO communicating over i2c

i am not able to communicate over i2c with my esp-01 as master and UNO as slave. i get special characters sent back to esp, but my esp is sending correctly... output on my esp-01 output on my UNO is ...
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1answer
689 views

scroll text through multiple i2c connected dot matrix displays

I have 4 dot matrix displays, every one of them connected to an i2c and accessible with 0x70, 0x71, 0x72 and 0x73. All these work just fine when I address them apart. What I want to achieve is a ...
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4answers
3k views

Strange problem. Arduino stops working after few hours. Opinions please

I am trying to setup an automated relay for my aquarium. The Arduino should switch off the pump every 3 hours for 20 minutes, and feed at particular times during the day. The code works fine for the ...
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1answer
515 views

Arduino UNO inconsistent I2C register reading from ArduCam

I have an Arducam hooked up to an Arduino UNO. The code I am running looks like this: #include <Wire.h> #include <ArduCAM.h> #include <SPI.h> #include "memorysaver.h" const int CS ...
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1answer
230 views

Configuring IO18, IO19 for I2C connectivity on Intel Edison Kit for Arduino

Intel Edison Kit for Arduino Hardware Guide instructs: echo 28 > /sys/class/gpio/export echo 27 > /sys/class/gpio/export echo 204 > /sys/class/gpio/export echo 205 > /sys/class/gpio/...
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1answer
284 views

LCD Display hangs the computer

I'm trying to connect 16x2 LCD screen to clone Arduino UNO via PF8574T backpack. 4 cables are connected to +5V, GND, SDA and SDL pins. When I tried this I2C scanner code from arduino.cc. It returned ...
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1answer
432 views

Proxying streaming i2c data(int values) to serial

The following code works correctly in reading single int values. It also works correctly for 3-4 seconds if I 'stream' the values in constantly (Mouse move coordinates) before I get an IO error and ...
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1answer
594 views

Slow refresh rate on I2C OLED screen

I'm trying to create a small handheld console with 6 buttons and an I2C 0.96" OLED display: https://imgur.com/a/AKiRMWN The directional buttons use the analog pin and different resistors technique to ...
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1answer
719 views

AtTiny44 and AtTiny 85 communication

I'm working on a project where I use two microcontrollers: an AtTiny44 (20MHz ext clock) and an AtTiny85 (8MHz internal). What I'm trying to achieve is an I2C communication between the 85 and the 44, ...
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1answer
557 views

PCF8583 with Arduino delay of one second?

I'm trying to interface the RTC chip : PCF8583 with Arduino Uno. I'm using exactly the circuit shown below except instead of the variable capacitor near the crystal oscillator, I've used a 22pF ...
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1answer
197 views

DFROBOT I2C 16x2 Arduino LCD Display Module I2C communication interface

What is the proper connection to the I2C communication interface (e.g., JST Jumper 4 Wire Assembly) of the DFROBOT I2C 16x2 Arduino LCD Display Module (SKU:DFR0063)? I wish to connect 4 wires assembly ...
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1answer
283 views

How to change IIC (I2C) clock rate on MKR1000

The IIC clock defaults to 100kb, need to increase it to ~200kb. I've tried: changing the constant TWI_CLOCK and rebuilding Wire.cpp calling initMasterWIRE(200000) after Wire.begin(). I'm using a ...
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2answers
2k views

I2C Arduino ESP8266 Bad Reading

I have a NodeMCU, which I program with the Arduino IDE. I have connected a VOC sensor to pins D1, D2, which are the SLC/SDA pins for NodeMCU. They have pull-up resistor at 4,3kohm to 3.3V. First I ...
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1answer
258 views

Fastest reading through i2c

I have an ADXL345 accelerometer and I read it with an arduino through I2C. I want to get readings at a frequency higher than 500Hz. According to the documentation this should be easily achievable, ...
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3answers
56 views

What do I have to change to make this code functional?

I have a joystick, an I2C 16x2 character display, and an Arduino. I want to move the joystick and get an on-screen character (specifically, the letter h) to move in the direction that I pushed the ...
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1answer
377 views

Start I2C communication at an external event

I'm working on a Arduino Uno and a ADC ADS1115. Devices communicate by I2C where Arduino is the master. I would like to use the ADC to the maximum of his possibility. So i configure the ADC to set a ...
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0answers
42 views

Adding oled library stops sound from working?

my code is using keypad library and oled display and piezo element. Without the oled code added everything works just fine. as soon as I add code for that, sound stops working. doesn't even call the ...
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1answer
45 views

Arduino detect order of objects

I'm trying to find a way to detect blocks being placed on grid on a table. The table will have fixed places where you can place the blocks, but the user is allowed to place the blocks in any free slot....
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1answer
93 views

16/2 arduino I2C lcd display not lighting up?

I am working with an I2C lcd display with an arduino uno board I have connected the gnd pin to gnd of arduino uno and the vcc pin to 5V of arduino uno and the display is not even lighting up there is ...
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1answer
64 views

Increasing speed of Vl6180x Sensors

I have 5x vl6180x pololu ToF sensors. I have managed to hook up all of the sensors to the arduino via I2C by making each sensor startup at different times and when they do, changing their addresses, ...
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1answer
183 views

What is best way to get data from sensors if arduino is slave?

Im working on a project where i have motor controller(arduino nano) being i2c slave. Its job is to get RF24 data and control motor and at same time send data to master about motor... Currently i have ...
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1answer
12k views

NodeMCU with RFID RC522 and I2C interface LCD module together

I'm newbie in Arduino programming so I hope to get a clear answer. I have NodeMCU v1 12-E, I connected it with RFID RC522 as in attachment picture. Now my question: I need to connect I2C interface ...
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1answer
2k views

MPU-9250 IMU on SPI, external sensor or magnetometer using I2C master

I'm trying (for sport...) to use an MPU-9250 in SPI mode as it should be faster, and wasn't able to talk to the embedded magnetometer in my code. I've gone through the documentation (RM-MPU-9250A-00 ...
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1answer
706 views

How to request data via I2C?

How do you program an Arduino Uno to request data over I2C, sending parameters defining the request? I'm trying to program Arduino A to read a sensor value from another Arduino B, and it first needs ...
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1answer
309 views

How to wirelessly communicate with I2C infrared thermometer

I've been getting involved with arduino recently as a means of improving a heating device which is quite small, a box about 15x10x5cm which I would like to rig with an MLX90614 infrared sensor. The ...
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2answers
256 views

coding problems

I'm working on a Arduino controlled solenoid motor project that I found on Instructables. I have been able to piece together what I think is most of the code but I'm getting some syntax errors and was ...
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2answers
451 views

Transmit data to long distance (120m)

I want to transmit data from multiple sensors to an Arduino and distance would be approximately 120 meters. What protocol or configuration should I use? Actually I am trying to read values from 5 ...
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1answer
395 views

Control multiple MPU9250 to start collecting data at the same time [closed]

Is it possible to use multiple MPU9250s for data acquisition at the same time? I want to use 10 MPU9250s in human motion capture, but how make all MPU9250 work at the same time so that make the data ...
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1answer
71 views

Arduino as Slave on I2C bus to read data from other I2C devices

Good afternoon; I am a bit new to the world of I2C bus. I'm trying to implement a project that have Arduino MEGA as a master and Arduino nano as slave. I have some I2C sensors that i want the slave (...
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1answer
93 views

How to use I2C library

My A4 and A5 pins are already hooked up to a LCD and I want to connect a MPU6050 as well. In a separate thread, someone told me to use SoftI2CMaster library to use other pins as SDA ans SCL. But I don'...
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2answers
87 views

How to make an I2C device undetectable

Please bear with me as I am a bit new to electronics and arduino. I am trying to have multiple sensors connected to an Arduino Mega through I2C Bus. That is working but I would like to have the ...