I²C stands for Inter-Integrated circuit, and is a data transferation system that allows connections between computers and low-level peripherals.

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Microstack Accelerometer not working. I2C issue?

I just received a Microstack Accelerometer about a week and a half ago. I put the Accelerometer onto the Microstack Baseboard and followed all of the instructions that were provided here. When I go ...
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28 views

Why is I2C disabled by default?

It seems that, to use I2C, we need to: un-blacklist I2C with sudo nano /etc/modprobe.d/raspi-blacklist.conf enable I2C kernel module with sudo nano /etc/modules Why is it disabled + blacklisted by ...
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1answer
52 views

Can't activate I2C on my B+

I'm trying to use the I2C pins on my Pi. All guides I can find talks about that I have to activate it using ether /etc/modprobe.d/raspi-blacklist.conf or raspi-config. However, nether works, the file ...
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15 views

How do I access the Wii Nunchuck using WiringPi

The Wii nunchuck is an I2C accessible device and can be wired to the I2C pins of a Pi. How do I read the data from a Wii nunchuck in C using the WiringPi library?
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22 views

Troubleshooting MCP23017 based display

I am having trouble getting characters to display on my Adafruit 16x2 blue/white monochrome LCD + keypad. I am wondering how best to isolate the problem as either hardware or software. It shows up in ...
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1answer
59 views

BMP180 allow to read calibration but fail to read data

I have BMP180 connected to my pi, i can read calibration data from it, but when i try to get pressure / temperature data -- i get 80 00 for temp and 80 00 00 for pressure (mean -- 'just-after-reboot ...
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1answer
54 views

What bitrate can I get from an i2c bus?

In short, what is the maximum bitrate that can be achieved writing to an I2C bus from a Raspberry Pi? Should it be the theoretical maximum of 100KB/s? In more detail, I'm writing to an I2C bus from ...
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36 views

Smallest possible baudrate for i2c?

I set it to 1200 $ cat /boot/config.txt [...] dtparam=i2c_arm=on,i2c_arm=on_baudrate=1200 but $ cat /sys/module/i2c_bcm2708/parameters/baudrate 3814 Is this the minimum? Can I somehow go below ...
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46 views

Problems Bit-Bashing an I2C Slave

I have a Pi B+ on which I'm trying to bit-bash an I2C Slave in C / C++ (code's pretty much C despite the fact I'm using g++ and .cpp files), utilizing GPIO 18 as my Clock and GPIO 17 as my Data. I'm ...
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2answers
61 views

Locating I2C pull-up resistors for RPi2

I am working with a project where the I2C pull-up resistors need to altered. Unfortunately i cannot find any documentation that can tell me: (a) if there is any pull-up resistors and (b) what size ...
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72 views

How can I use a LCD display with a I2C adapter?

I'd like to try to communicate to a 16x2 LCD display, however whole docs I found assume I should connect the whole pin-out however I got some kind of I2C adapter from mjkdz.com which makes a 4 pin ...
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2answers
82 views

Resetting I2C? Or did I break my chip?

I'm connecting a TS45315 light sensor on an Adafruit breakoutboard to the I2C bus of my Raspberry. I access the data through the following simple Python script: ...
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1answer
107 views

I2C not working as expected

I'm running a Pi B+ rev 1.2 and recently acquired 2 I2C modules: DS-RGBW.S LED lighting Microstack accelerometer: When connecting the LED module, address 70 appears to be occupied as planned. I ...
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1answer
94 views

What does raspi-config do when you enable i2c?

Is there any documentation for the raspi-config command that would explain what it actually does when enabling i2c? In the past I have just removed the i2c blacklist, added the modules and made sure ...
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1answer
80 views

I2C LCD detected, code runs, but no display

I'm trying to drive a 16x2 LCD board with i2c and running into some unexpected results. Basically, I can detect it, talk to it with my code, but nothing shows up on the screen. Same screen when ...
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21 views

Changing from spi bus to i2c bus to transfer register data of wm5102 in raspberry pi with wolfson audio card

I'm using wolfson audio card on raspberry pi b+ board.Current wm5102 driver uses spi bus to transfer register data but i want to use i2c bus to transfer data.By reading data sheet of 5102 i understood ...
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26 views

Using sensors and dc motors with MCP23017

Can I use a Raspberry Pi Model B along with MCP23017 to take inputs from 5 digital sensors and give output to 6 'normal' 12v DC motors? The Pi is already working as a webserver with a USB camera. I ...
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23 views

How to set up MPU6050's registers properly?

I would like to use the MPU6050 as IMU in my quadcopter. I've been Googling for 2 days, but I can't find anything where there are explained well. I know that the settings are not general, but I hope ...
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1answer
62 views

Accessing ADXL345

I'm trying to access an ADXL345 Accelerometer mounted on a Sparkfun breakoutboard via Python and I2C from a Raspberry B+. I'm following this tutorial However when trying to check for the sensor with ...
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138 views

Different “Adafruit 16x2 Character LCD + Keypad for Raspberry Pi” Python Libraries & Sunfounder plate

I have the SunFounder I2C interface 16x2 LCD Pi Plate with KeyPad with RGB LED for Raspberry Pi plate (this model available at Amazon (sorry I have only the german link - the picture is showing the ...
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2answers
104 views

Rasclock does not store the time

I just received my Rasclock V4, and set it up according to Afterthought's instructions. Seeing as I'm doing this on a RPi B+, with the latest raspbian image downloaded from raspberrypi.org just ...
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1answer
68 views

Python, C, I2C, calling binary with arguments, and printing output

I have a C binary that takes 1 argument. I need to have Python run the binary, and return the output. Using subprocess.Popen (and check_output), the C binary fails when trying to write to the I2C ...
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1answer
55 views

baudrate config changes only after starting x

I've changed an i2c config file so current baudrate is 300000. I do a reboot and start an i2c baudrate checking program. sudo ./checkbr But what I get seems to be usual baudrate settings(default). ...
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67 views

MPU6050 gyroscope not responding

I was testing my MPU6050 with Raspberry PI and got accelerometer(X,Y,Z) and gyroscope(X,Y,Z) data forming on registers at decentely high sample rate. Looks like I've accidently fed +5v from RPI to SDA ...
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9k views

Firmware 3.18.x breaks I2C, SPI, audio, lirc, 1-wire (e.g. /dev/i2c-1, No such file or directory)

I am using i2c to control a Bright Pi module. I followed instructions from 'Configuring GPIO - Adafruit' and 'Configuring I2C - Adafruit' to set up the I2C. I have done this a few months ago and ...
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43 views

I2C PIC18F2520 and PI

I am having a big problem to communicate a PI with PIC using I2C. When I try to use another PIC as master everything works fine, no problem. But swtich to PI I cant get it to work. To start my both ...
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195 views

Why I cannot read the temperature/humidity sensor sht20?

I use a temperature and humidity sensor sht20. According to this link: http://www.sensirion.com/en/products/humidity-temperature/humidity-temperature-sensor-sht2x/ It is compatible with sht21, which ...
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129 views

Why my Raspberry Pi cannot find Si7021 (temperature and humidity sensor)?

I use this temperature and humidity sensor: Si7021, like below link http://www.dfrobot.com/wiki/index.php/SI7021_Temperature_and_humidity_sensor_SKU:TOY0054 I can get the sensor data by Arduino ...
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1answer
87 views

Check for I2C device presence

I'm using I2Ctools to read data off of some devices attached to a raspberry pi via the I2C interface. I want to check if a device in a certain address is present or not. If present, read the data from ...
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83 views

Sending data to a 1602 LCD in Mono C# over i2c

How would I be able to put information on a 1602 lcd over SPI? I was thinking that it may be possible to write to the pin (like a file) with all the hex codes of the letters etc. or similar. I'm a ...
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292 views

i2cdetect strange output

I'm following this tuto http://skpang.co.uk/blog/archives/575 in order to setup my rpi with an I/O port expander. My problem is whenever I run i2cdetect to find out the device, I get a weird output. ...
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216 views

Controlling a official lego servo motor via Raspberry Pi

I am able to control a simple servo motor such as SG90 by using pulse-width modulation. However when it comes to controlling a 88004 LEGO Servo Motor it is simply a nightmare. By using PWM all I ...
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1answer
96 views

Troubleshoot MCP23017 and LEDs

Anyone have any tips to help troubleshoot turning a simple LED on connected through the MCP23017? I've installed i2c-tools, and smbus. Nothing in my blacklist.conf Added i2c-dev to /etc/modules. ...
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154 views

Connecting Adafruit NFC breakout and serial console at the same time [closed]

I am electronics newbie but have some programming background. My current hobby project is to make a "thing" which does things based on which NFC badge is waved at it. The tutorial [1] I am following ...
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1answer
66 views

I2C device inside case + GPIO ribbon outside case

I have a model B in a nice prefab case with a slot through it to connect a 26-wire ribbon to the GPIO header. However, I'd like to leave a small I2C based device inside the case as well. I've ...
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56 views

Issues with multiple SDA sensors

I am facing some issues trying to connect two sensors which make use of the SDA GPIO. Ultra sound sensor HC-SR04 Gyroscope & Accelerometer MPU-6050 Separately, they work just fine, however ...
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1answer
56 views

Sensor minimum/maximum operating voltage

I've bought this sensor, and I'd like to connect it to Raspberry Pi (unless I manage i2c on dagu minidriver). The spec on the sensor say: Minimum operating voltage: 2.5 V Maximum operating ...
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74 views

Pins I2C cannot be used as input

When using pin 3 and 5 as inputs, I get only 3.3v and I'm not able to use them as inputs. I use the same code and circuit on all the GPIO pins the circuit worked on every single pin except on this 2 ...
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44 views

How to do a repeated start with the Raspberry Pi to get the MMA8452Q accelerometer working?

I am trying to use an MMA8452Q accelerometer with the Raspberry pi B+. I have it hooked up to 5 GPIO pins on the Pi, J8 pins 1/3/5/7/9. After installing some i2c libraries, the Pi recognizes the ...
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669 views

I2C problem reading data - only sometimes

I'm using this device, that acts as an I2C slave device on the address 0x23, for communicating with an arduino from a RPi model B. This is an nrf24l01 attached to an AT48 that provides an I2C ...
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1answer
96 views

Filtering noise w/ pi as FM transmitter and sound source

I have an I2C FM transmitter for the pi; it has a 3.5mm stereo jack for input. Everything works great -- I attached a short dipole antennae and get clear reception for at least 25'. However, if I ...
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195 views

Daisy Chaining MCP23017 & Addressing

I'm looking to daisy chain multiple MCP23017 chips (upward of 10) to essentially give me more IO to play with from my Pi. I've started to work on the circuit diagram, but I'm really lost with all ...
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2answers
128 views

I2C receive handler, as seen on I2C for Arduino

When managing smbus/I2C devices using python with the RPi, is there a way to register a handler function so it is called when a byte is available for read, like in Arduino Wire.onReceive()? Otherwise, ...
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75 views

Check whether an I2C slave device is ready or not

I'm using an I2C device connected to an RPi. The device only handles receiving one byte (which is then transferred via radio to a similar device on the other end, that acknowledges the reception of ...
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1answer
31 views

i2c connection to mopi not working on one image

I'm trying to setup a mopi on my model B running raspbian. At the moment I can't talk to the mopi unit using the mopi and mopicli utilities and i2cdetect shows the following... $ i2cdetect -y 1 ...
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55 views

PWM to control brightness on i2c LED backpack?

I have something similar to this, it works, but it's too bright! I am aware that LED brightness can be controlled by pulse width modulation, but I don't know if I can safely do that with an LED ...
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171 views

Basic hand (touchless) gesture detection, solution needed

I need a good solution for basic gesture recognition (touchless), like swipe left, up, down, right, "tap" hardware/software for Raspberry Pi. I've seen http://www.hoverlabs.co/#hover which looks very ...
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2answers
259 views

Use interrupts in i2C between Ardiono and Raspberry Pi

I'm really new to Raspberry Pi and Arduino programming (+ I2C). Recently I start working on a project where I have to connect an Arduino and a Raspberry Pi to send and receive data from each other. ...
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75 views

I2C and ST 24C64 (5V Problem)

I`m planning to use the 24C64 EEPROM with my Rasberry Pi. According to the datasheet the EEPROM "Single Supply Voltage" is 4.5 to 5.5 V. (Datasheet: ...
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230 views

Sending i2c commands from arduino to pi

The RPi and arduino are connected by I2C and the arduino sends coordinates to the RPi through the wire library. However, the RPi only receives and prints out 0 when it should print out the coordinate. ...