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.

learn more… | top users | synonyms

1
vote
2answers
46 views

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 ...
0
votes
0answers
16 views

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 ...
0
votes
0answers
38 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 ...
3
votes
1answer
135 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 ...
2
votes
1answer
193 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 ...
2
votes
1answer
113 views
+50

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, ...
0
votes
1answer
18 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 ...
2
votes
1answer
37 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 ...
0
votes
0answers
29 views

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: ...
0
votes
0answers
33 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 ...
1
vote
2answers
47 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 ...
0
votes
1answer
56 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 ...
2
votes
4answers
483 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 | ...
0
votes
1answer
35 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 ...
1
vote
1answer
55 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 ...
0
votes
0answers
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 ...
3
votes
3answers
64 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 ...
2
votes
2answers
64 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 ...
0
votes
1answer
36 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 ...
0
votes
1answer
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 ...
1
vote
1answer
58 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 ...
1
vote
1answer
60 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 ...
1
vote
2answers
98 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) - ...
0
votes
0answers
36 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 ...
0
votes
1answer
31 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 ...
0
votes
2answers
79 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 ...
1
vote
1answer
55 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 ...
0
votes
3answers
200 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 ...
0
votes
1answer
40 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 ...
1
vote
2answers
112 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 ...
0
votes
2answers
46 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?
0
votes
1answer
60 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: ...
1
vote
3answers
71 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, ...
2
votes
1answer
58 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 ?
6
votes
2answers
100 views

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 ...
0
votes
1answer
43 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 ...
0
votes
1answer
112 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 ...
0
votes
1answer
93 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 ...
0
votes
1answer
64 views

why is ground needed to be common in i2c communication?

I'm using i2c for communication between arduino and SBT-150 thrusters , but the problem is that thrusters use 24V and arduino use 5V. So, i want to somehow isolate the two grounds for protection of ...
0
votes
1answer
104 views

Voltage regulator like LM 317 which can interface like SPI or I2C

Is there any variable voltage regulator IC similar to LM317 available the output of which can be programmed through a digital interface like I2C or SPI?
0
votes
1answer
190 views

TSL2591 sensor value calculation

I bought an TSL2591 breakout board and wanted to write driver for my board. After looking at the documentation, i found that i cannot calculate the illuminance value (in Lux) as their was algorithm ...
1
vote
2answers
83 views

Is it allowed to stop and restore I2C transmission?

Is it allowed to stop and restore I2C transmission? I would like to stop it in different periods of transmission and then after for example 500ms restore it to the state when it was stopped. I'm ...
4
votes
1answer
84 views

How long/big is an I2C acknowledge?

I'd like to know, how long/big should be an ACK from a slave to its master? I am communicating with a module using the I2C protocol. But the large blank space in the middle, is this an ACK from the ...
13
votes
5answers
1k views

Why the need for multiple I2C ports?

The I2C protocol allows, in theory and with 7-bit addressing, up to 127 devices to be connected to the master. This is a large number, so why would any low-cost microcontroller, e.g. this one, have ...
0
votes
2answers
49 views

MPU-9150 (IMU) - what happens at fullscale range boundaries?

We're debating the use of the MPU-9150 IMU in an application. This IMU has a user settable full scale range for the accelerometer (e.g. 2g, 4g, etc) and gyroscope (200dps, 400dps, etc). Suppose I set ...
0
votes
1answer
138 views

I2C-controlled digital counter

I need for a project an IC which should generate a digital signal with a length given by an I2C-signal, i.e. if I send the IC "50" (or something similar with the same meaning), I want to get 50 ...
1
vote
2answers
334 views

If an I2C device does not appear in i2cdetect does it mean the device is potentially broken?

I am trying to get an I2C OLED (128x64) display working on a BeagleBoneBlack. Unfortunately, no matter what I2C port I try I cannot see the device when using the i2cdetect utility. As you can see ...
0
votes
1answer
79 views

Is it possible to connect more than one device on the same SPI?

Is it possible for someone to connect multiple sensors to the same microcontroller's SPI or I2C port? If it's possible, how would someone alternate between devices?
1
vote
0answers
80 views

Microchip 9808 temperature sensor - Incorrect calculation result

I am using a Microchip MCP9808 I2C temperature sensor (https://learn.adafruit.com/adafruit-mcp9808-precision-i2c-temperature-sensor-guide/overview). I'm having problems being able to calculate the ...
1
vote
1answer
130 views

LSM9DS0's Accelerometer not reading correctly

I have a LSM9DS0 Gyroscope/Accelerometer/Magnetometer breakout board. I am using an Arduino Uno which operates on 5V. The LSM9DS0 is communicating to the Uno using I2C through a Logic Level Converter. ...