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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How do you wire up the OV3640 camera module?

I've been wanting to do a project with this module in mind and have found some resources on it (mainly arducam) but I have no idea how to connect it to a micro controller. The data sheets show that ...
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122 views

Does biasing of address pins require a resistor?

I'm a total newbie fooling around with a project of mine. I want to use a MCP23071 I2C port extender (Data sheet) for my arduino project. The chip has three hardware pins that must be externally ...
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143 views

I2C at 2.4 MHz with five microcontrollers over 2 meters

I have five Teensy 3.1 and I would like to interface them with I2C running at 2.4 MHz. The maximum Line Length will be around 2 meters. Will it work? What's the best way I can wire this up?
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Strange I2C signals emitted from FPGA

I have a ZedBoard FPGA device and I'm trying to implement an I2C interface to communicate with a camera module. I'm using Vivado 2014.2 and I have added an AXI IIC block to my design with the SCL ...
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Beaglebone black i2c-1 file write error

I am using beaglebone black i2c2 pin 19 and 20 of p9. Somewhere in the bet it was told i2c2 has told accessed with i2c-1 in /dev folder. I am booting default amstrom linux from emmc. Hardware is ...
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AVR Error Handling: I2C, SPI etc

How would one go about handling errors in AVR interfaces that do not specifically provide any acknowledgement scheme? For example, I have an I2C temperature sensor which I poll every 1 hour. So every ...
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140 views

HDMI and I\$^2\$C

I was having a look at the HDMI pinout and I thought: why would they use I\$^2\$C for the display-host communication? My question here is about the design metrics that lead to this choice. HDMI is a ...
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116 views

Properly grounding 2 MCUs using I2C

I'm building a mechatronic system that consists of 1)XY Gantry controlled with PIC32 and a DIY motor shield and 2)control box with PIC24 three potentiometers + room for expansion, typically located ...
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55 views

How to debug large I2C bus?

I have a circuit board with lots of soldered SMD chips. There are a few I2C components connected to the same bus and the bus is also connected to a "bus switch" isolation switch. Unfortunately the bus ...
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42 views

Arduino I2C level conversion

I'm working with Arduino Uno (Rev 3) to interface a DRV2605 haptic driver to control several ERM/LRA motors using I2C. As I look at examples on the web, I see everyone uses a I2C level conversor to ...
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Debug 2-Wire Serial Interface

How can I debug I2C in Atmel Studio (latest)? I have enabled it as shown inside the I/0 View with TWEN and ...
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9 DoF Sensor Accelerometer Readings Inconsistent

I have the following sensor stick: https://www.sparkfun.com/products/10724 It has an accelerometer, gyroscope, and magnetometer. I have connected it to an arduino and am reading the accelerometer ...
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66 views

USB Audio Stream to Codec

I have been trying to design a USB Audio Interface with an Atmel SAM3U microcontroller and I think I have hit a wall in my thinking process. As a sidenote, I'm relatively new to the world of ...
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154 views

Arduino: What is the best way to send and receive data with I2C?

I am using I2C to send and receive int values from a RaspberryPi to an Arduino then echoed back to the Pi. The primary problem I am having is with int values larger than 255. A secondary problem is ...
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422 views

Can I do without I²C pull-up resistors?

I am trying to produce a small circuit, and I am looking to reduce the part count. I recently added an I²C EEPROM which is used once when the system boots up, along with this EEPROM I added two ...
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2answers
62 views

Is it safe to not power this USB to I2C chip when USB isn't plugged in?

I am working with someone on a data logger based on an MSP430. Since it operates on battery power, we want the device to use as little power as possible. We are planning to use this chip (FT201X) to ...
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2answers
252 views

Can I use 74HC14 or NPN transistor instead of MOSFET as level shifter

I have SN74HC14 or BC548 / 2N2222 transistors. I need level shifter for I2C between arduino and RPi. Here's simple circuit from the internet Problem is I don't have any MOSFETs. Can I use NPN ...
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1answer
105 views

Porting Linux drivers specifically I2C

I am developing an I2C driver for an accelerometer. My objectives (actually it's the restriction I have as per the project guidelines given in my institute): use Linux flavour of operating systems ...
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1answer
27 views

AVR TWI Status Codes Complete List

Can anyone provide a link for complete list of status codes for AVR TWI? I am working with DS1307 using TWI, during which at some point I receive a status code of 0x40. However there is no mention ...
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308 views

Arduino Uno to ATtiny44A I2C communication

I tried to make I2C communication from Arduino Uno to ATtiny44A. Uno as Master and Transmitter code: ...
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2answers
115 views

How to drive a single 7 segment display with I2C?

I am looking for a solution to drive a single 7 segment display with I2C. I found some websites that shows 2 or 4 digits with I2C but I didn't find a solution for driving a single digit. I'm making a ...
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59 views

MMA8453 accelerometer I2C problem

I ran into an issue with my project. I use Renesas RL78 microcontroller and on one I2C bus I have two sensors: digital compass and accelerometer. Accelerometer type is MMA8453 by Freescale. ...
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315 views

I2C actually sends inverted data over the line?

It seems to me that I2C is actually transfering inverted bits which sounds a bit odd so I am seeking for a clarification. I2C diagram from here. Let's say we are writing to slave. A zero (0) comes ...
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118 views

Writing to register on I2C device, returns device busy

I am trying to write data to a register on an I2C chip from the Raspberry Pi, when I use i2cdetect I get UU, which I understand is an error. ...
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How does multimaster I2C work and its significance?

I am fine with I2C basic communication and implementation? Need info on Multimaster mode of I2C How does multi master I2C work? Advantages over I2C single Master? In what circumstances this multi ...
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75 views

Arduino I2C and multiple devices

I have created two projects, one with a Tiny RTC and another one with the BM180 sensor to read barometric pressure and temperature. Now I want to combine both. I'm trying to connect both - the ...
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4answers
164 views

Connecting a 9V IC's I2C interface to 3.3v Arduino DUE

I need to connect a TDA7312 to Arduino DUE's I2C interface via SDA/SCL. TDA7312 operates on 9V, Arduino DUE is 3.3v. Is it possible to safely connect it, without burning it? Or what should I use ...
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2answers
142 views

Reason for choosing SPI based flash devices over I2C ones [duplicate]

I have gone through the below link which says that u-boot support three type of flash technology http://www.stlinux.com/u-boot/flash 1.Nand 2.NOR 3.SPI Serial Flash I would want to know why SPI is ...
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I2C Enabled LCD Unreliability

I'm trying to control an I2C Enabled LCD Display using the STM32F0. I have a bunch boards built with the LCDs and a couple of them work all the time, a few work intermittently and a few rarely work at ...
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70 views

Combine protocols on a U/FTP Cat 6a cable (USB 2.0/I2C)

Main question Can I use a Cat 6a cable for USB communication? On the cable it says 650 MHz, is this sufficient for USB 2.0? The length of the cable would be about 6 meters (about 19 ft). If so, would ...
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1answer
78 views

How to read SAA1064 7-segment values

I have a central heating system that displays it's info and error codes on 4 7-segment displays. These displays are driven by a SAA1064, like so: This SAA1064 (datasheet here) receives it's ...
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72 views

Serial comms over 3m cable, shared with USB

I am designing a system that needs to do serial comms over a standard USB cable, as well as normal USB (but not at the same time). In other words, when plugged in to a PC it will appear as a USB ...
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90 views

I2C - connecting 5V device to 3.3V host

Is it safe to connect any 5V I2C slave device to 3.3V host? I know, that DS1307 realtime clock can be connected to Raspberry Pi (3.3V IO), because DS1307 just pulls down data lines and 5V voltage ...
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74 views

BSS138 levelshifter draws 35-40mA current when one side is grounded?

I completely rewrote my question as I found the source of the issue is related to the level shifter only. This is the circuit for a 3.3V to 5V bidirectional levelshifter, used frequently. My ...
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0answers
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Bosch BMI055 Accelerometer/Gyro causes I2C bus to crash when issuing a softreset!

Datasheet: http://ae-bst.resource.bosch.com/media/products/dokumente/bmi055/BST-BMI055-DS000-06.pdf I have recently integrated the Accelerometer of the BMI055 I added a soft reset of the chip at ...
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2answers
216 views

Best way to do I2C/TWI over long distance

I have a project that requires to do I²C/I2C/TWI over a long distance (30 to 40 meters). I've seen some people suggesting lowering the clock-rate to somewhere around 500 Hz, to mitigate the effects of ...
2
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1answer
135 views

AVR TWI (I2C) problem

I am using ATmega32A and 24c16A EEPROM for testing an I2C code. For every state transition, controller responds by changing the status register TWSR. After start ...
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3answers
371 views

Can I use both I2C and SPI at same time with PIC16F1503

Im new to Microchip microcontrollers and I'm looking for very low cost device with I2C and SPI. I want to connect one I2C (ADC) and one SPI device (LCD). I found this very low cost device: However ...
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GY-521 Unable to set PWR_MGMT_1 register - can't disable SLEEP mode

I am attempting to interface between a custom 8051-based MCU and a new (ebay) GY-521 module (Gyro/Accel chip) using I2C bus. I have written the I2C bit-bang functions myself and they seem to be ...
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1answer
71 views

SWD and i2C hardware layer differences

Both I2C and SWD are two-wire protocols. I wonder what are the main differences of the hardware layer of these protocols and what are the pros/cons of each one? It's also interesting that the maximum ...
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Sending I2C reliabily over Cat5 cables

I am considering implmenting an home automation system around my Raspberry Pi but I found the price and space requirement of inserting a Pi every place some control is required too much but the Cat5e ...
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2answers
166 views

How to avoid short circuit when connecting a microcontroller and device using I2C bus?

I am attempting to connect an 8051-compatible microcontroller to an accelerometer using the I2C bus. Both devices operate at the same voltage, 3.3v. However, I am failing to understand something: ...
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1answer
135 views

Can I2C bus be left open circuit?

While trying to make a TV tuner radio like I saw here I got myself a I2C PLL Tuner from an old TV and powered it up without connecting I2C bus lines to the circuit. Not even to the pull-up resistors. ...
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1answer
46 views

help with QT1070

I am using AT42QT1070 touch IC in comms mode with I2C communication.I have used 10k pullups with SDA and SCL line and 47k pullup with CHANGE line(active low) as mentioned in datasheet. The CHANGE ...
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2answers
487 views

What do hardware address pins do?

I have been delving deep into digital logic and am trying to understand some memory architecture basics. I have started looking at data sheets to get a grasp on some real-world components and noticed ...
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5answers
166 views

Maximum I2C Bus Length?

What is the maximum length of cable that could be used to connect two I2C devices (I2C master-> I2C slave)? Yes, I know that I2C is really designed for intra-board communication. I have been tasked ...
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1answer
57 views

NXP i2c temperature probe locking up

I have an issue with an NXP SE95 temperature probe that has been working just fine up until now on other systems. At some point, either on boot or soon after, the probe will have some sort of meltdown ...
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2answers
137 views

Unpowered devices on I2C/SPI bus

I'm trying to develop a board that includes I2C and SPI devices that are unpowered for the majority of the time to save power. I found that for these particular devices (Honeywell HSC pressure ...
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1answer
150 views

Problems with I2C on PIC18F25K22

I've been googling for about two weeks now and I still can't seem to get my I2C working. I've used this (what seems to be complete) tutorial. I followed the Master Write and Master Read examples to ...
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1answer
244 views

Problem using DS1337 - RTC

I am trying to use a edited version of the library given at this link. I basically changed some of the included file and some of the changed function of the wire.h library. Though I am not a hardcore ...