I²C (Inter-Integrated Circuit) is a multi-drop serial bus invented by Philips (now NXP) for communication between ICs on the same PCB, i.e. short distance.

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What are the address input pins used for in ds1621?

I just bought a ds1621 temperature sensor and started reading its datasheet. I found out that it have 3 pins (A0,A1,A2) which as specified in the datasheet are chip address input. Can somebody ...
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Measure I2C bus capacitance

We are trying to calculate how many I2C slaves we can hook up the I2C bus. We tried to run a square wave through a serial resistor and measure the rise time but we get a strange result. More nodes ...
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NVT I2C bus capacitance

I would like to use NXP NVT20XX as bidirectional voltage-level translator in my system (I2C at 100kHz, 6 slaves) and I only don't understand one thing. I am little bit confused. In the datasheet they ...
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Connect large number of MPU 6050 I2C devices

I am quite new to electronics , in my project I am trying to connect large number of MPU6050s(about 10 sensors) I2C devices and try to get the reading 'simultaneously'. Some questions that I am not ...
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58 views

how to communicate between 3 devices

i want to communicate between uno, mega and netduino, which protocol should i use i want the uno and mega to send information to the netduino which mean that i don't need duplex connection which mean ...
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57 views

Fixing a noisy I2C bus

I'm trying to get an I2C bus working but there's a ton of noise and I don't really know what's causing it. The circuit is pretty simple, an ITG-3200 and an Arduino DUE. Here is the problem: As you ...
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50 views

I2C hanging after 2 minutes

Background Information I am designing a small PCB for 4* I2C devices, the baud rate of the I2C is not a major issue so 100kHz was the target. The I2C devices are a RTC, LM75, 24AA04 and a MSP23017 ...
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I2C slope control for falling edges

I2C has this requirement in the spec for slope control on the falling edge @ 400Khz. It appears it's to make it so it doesn't fall too fast. I read somewhere else this was done for EMI purposes, ...
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LPRF design on 4 layers

Developing a new design on a 4-layer stack with reduced dimensions, there are some doubts I expect you can help me with. The board includes RF part, MCU, voltage regulator & battery charger. ...
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62 views

Problem with I2C on PIC18F25K80

I am trying to configure an I2C protocol between a PIC18F25k80 and a barometric pressure sensor (the link for the datasheet is provided below). I can't figure out what the problem is. Initially it ...
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34 views

Will a I2C switch boost the overall bitrate?

I am currently working with a wired I2C bus system consisting of 6 individual bus lines with 4 slaves on each. They are currently all connected to one I2C bus and for each slave i add the bus becomes ...
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rasperry pi with i2c arduino leonardo

I'd like to connect a Raspberry Pi A+ with an Arduino leonardo. I'd like the rapsi to be able to upload HID sketches on the arduino.Then I'd like the arduino to run the sketch over the USB interface ...
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How many bytes can be sent in a single i2c message?

I've been working with i2c lately between a beaglebone and an Atmel 328P where the Atmel controls a number of devices under the direction of the beaglebone. In order to accomplish what I've done so ...
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Relation Between 8:1 Mux Signal , Mux Accessing Time & output of Mux

I have asked a question yesterday . Now i have a strange issue. I am working with Beaglebone white in Android platform . I have one external ADC (ADC121C021CIMM - connected through 8:1 Multiplexer ...
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89 views

MPU6050 DMP values read

I am using MPU6050 breakout board IMU along with ATtiny2313 microcontroller to get the accelerometer and gyroscope values from the IMU. Here's the question : I want to know what values are computer ...
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144 views

Relation between ADC register value & ADC accessing time?

I don't have any Electronics background.I am Software Engineer. I want to know that is there any relation between accessing the ADC buffers with a time (T ) & the ADC buffer values. I am working ...
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209 views

Interfacing 2 accelerometers through I2C

I am looking at designing a system where 2 accelerometers are connected to a microcontroller using I2C however I am unsure as to how this would actually work. In particular would I need a ...
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1answer
168 views

Raise input for a voltage monitor IC

I was looking over LTC2990, which is a voltage, current and temperature monitor. It is perfect for my project as I'm newbie. I want to build a power supply which will show on a display the voltage, ...
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38 views

Controlling an ESC for Brushless Motors with an RPi

Originally posted on Robotics, but guess it's not active enough. I'm looking to build a new (first) quadcopter without the conventional flight controller and radio, with an onboard RPi and applying ...
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1answer
96 views

STM32F3 Discovery reading values from sensor using I2C

I need to read values from on-board LSM303DLHC (connected via I2C) sensor and send them through UART. UART part is working but PuTTy shows: "S▒▒" every restart... Can anyone tell me what's wrong? I ...
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Microchip PIC18F24K50 I2C master talking to SHT21

I'm building a library to talk to an SHT21 Temperature/Humidity sensor using the XC8 I2C libraries. I have the following functions: ...
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63 views

I2C Slave on ATtiny841

I am using an ATtiny841 microcontroller as an I2C slave, but I have difficulty finding information on it. So for, all I have are application notes and reference code for TWI and USI module. It seems ...
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49 views

Using internal pull-ups for TWI on AT32UC3B?

Does anyone know if it's possible to use the built-in pull-ups for TWI on the at32uc3b chips? I've been adding external pull-ups to my TWI circuits in the past because I couldn't find any concrete ...
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78 views

problem of transmitting data from serial device to bluetooth on Arduino

I am using an accelerometer which uses serial communication on Arduino (UART), I wish to transmit the data to a bluetooth module (blusmirf gold) using I2C and finally read it from my android ...
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494 views

Do all I2C devices have separate read and write addresses?

I'm using a particular I2C device, and when it is connected, I need to write data to it by sending data to address 0x30 but then to read from it I need to read from address 0x31 (or by doing 0x30 | ...
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52 views

FT232H read ACBUS9

First time on this board so you will excuse me if the question has been answered before ... Right down to the nitty-gritty I have a board based on an FT232H chip, AD bus is used in I2c to ...
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68 views

Slave I2C timing relative to master clock edges

I am working with the STM32F4 microcontrollers. The I2C peripheral uses a clock setting. I have been told that it does not matter when the peripheral is used as the slave device. If that is true ...
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25 views

Turn on/off serial and I2C display [duplicate]

I have 2 character display, one is controlled by serial another is controlled by I2C. I could control both with serial or I2C alone. But that's not the point. Now what I want is, to completely turn ...
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72 views

ADC with I2C interface with multiple addresses

I want to connect 31 ADC slaves to a master. The ADCs simply should measure voltage and response its values to the master after request. I thought about using I2C as bus system. The problem is that ...
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2answers
72 views

Sensible standard wiring type for long-range I2C

I'm planning on interfacing with some sensor devices via I2C over a long bus, with devices chained every 2m or so, up to 16m in total. I've seen other questions here referring to this from the "which ...
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1answer
48 views

Control LCD with TIP121 on Arduino not displaying anything

I'm trying to control the power of an LCD I2C display. My project uses and Arduino and LCD, but when Arduino goes to sleep, the LCD stays on. So, to solve this problem, I connected a TIP121 transistor ...
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21 views

Texas Instruments Page/Register Convention - how to find the actual register address?

I am having troubles understanding TI datasheets regarding their DACs... I haven't felt so stupid for quite a while! To make things as transparent as possible, here is a very literal question. I am ...
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82 views

I2C level converter stops bus [closed]

I am trying to get an lcd 16x2 with PCF8574 I2C working with my arduino due. If i connect my lcd with 3.3v (backlight doesn't work, led from the PCF8574 lights up) and upload the i2c scanner sketch ...
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89 views

i2c communication between cc3200 and at42qt2120

I am trying to do i2c communication between TI's cc3200 and atmel's touch IC AT42QT2120. I am able to read and write to different memory locations of the touch IC, but i am unable to get it's change ...
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118 views

Connecting i2c slaves to master over RJ45 style cable?

I'm desigining several modules (e.g. sensors, motor controller, etc.) that need to communicate over I²C. These modules can be up to 15ft (5m) away from the base module (I²C master - Spark Photon) - ...
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38 views

CSI/DSI over one meter cabel

Imaging you have a smartphone where the display and the camera is attached with a one meter long cable. What would be the best and most power efficient way to transfer camera (CSI/I2C) and display ...
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44 views

ADXL 345 Noise Issue for my use case

I am building a solution where I want my MCU to wake up based on a trigger generated by accelerometer after detecting an activity. There are a number of samples available for this and I am able to ...
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2answers
81 views

Cheapest way to get a CAN signal

I have to transfer signals over around five meters. My input signals are I2C or SPI-compatible, but unfortunately it is no good idea to transmit them over such a long distance. Therefore I was ...
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1answer
69 views

Adding High Byte and Low Byte of LSM303DLHC Accelerometer Output

Interpreting LSM303DLHC Accelerometer Output Hi all, This is my first StackExchange question ever, so I will do my best to be specific and offer as much reference as possible. I'm currently ...
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3answers
201 views

How to achieve 57 PWM outputs most easily and cheaply

I need to light up 19 RGB LED strips, which it seems would require 19*3=57 PWM outs and 57 transistors. The transistors aren't an issue, but of course the 57 PWM's is. Most micro controllers simply ...
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41 views

Does SMBus spec lie about I2C?

In the SMBus spec it says: The I²C specifications do not require that a device always acknowledge its own address. This can confuse a system controller. If a device does not acknowledge its ...
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2answers
160 views

LMP91000 I2C Write Problem

I've posted this question to TI E2E forum here. I'm cross-posting it here in hopes of casting a broader net. I'm writing an Arduino library for the LMP91000 (github), and I'm apparently having some ...
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51 views

Why there is no high voltage repeater / voltage translator ic (like max232) for I2C

why I2C don't work don't work with long wire, for UART we have 10 volt translators like max232, for I2C why there is no high voltage repeater ic?
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81 views

PIC24 I2C status bits not set

I am working with PIC24FJ192GB106 (64 pin package), and the I2C module is driving me crazy. here is the code: ...
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3answers
87 views

PIC24 - testing I2C module dead/alive

I got PIC24FJ192GB106 (64 pin package) and I cannot get the I2C module working at all. What is the easiest and most straight forward way of testing, whether the module is OK? I am using I2C1 module, ...
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1answer
84 views

EEPROM in beaglebone black

I want to disable EEPROM in beaglebone black by unloading i2c-omap driver. Will it create problem in hardware or any other software support? What should I expect ?
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How to display I2C address in hex

The I2C communications bus uses 7-bit or 10-bit addressing to address slave devices. Taking the more common 7-bit addresses, each packet sent on the bus by the master starts with an 7-bit address ...
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47 views

Can sampling I2C influence transmission?

I have 200 kHz I2C communication and I am monitoring it with Logic Analyzer that has 100 kOhm input impedance. When I set sampling rate at 2 Mhz everything looks good on the time diagram. On the other ...
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151 views

Mixed SPI and I2C using ATtiny USI

I've been successfully using the USI on an Attiny84 to talk SPI to a radio module. This is good for hacking up sensors and whatnot as little radio devices. My next sensor project involves a sensor ...
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111 views

Will MCP23017-E/SP be compatible with an ATtiny85? ATmega328P?

I mainly want to also be able to use the same I/O expanders with ATTiny85 projects since those chips have limited pins. I will be doing the main prototyping on an ...