Questions tagged [i2c]

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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8051 to I2C backpack/4 bit LCD Byte Construct Probelms

Been feverishly writing bit bang code in assembly for this I2C backpack/4 bit LCD and dont quite understand the binary constructs I need to display text. Im trying to learn this the real way, not the ...
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Simultaneous reading of multiple I2C devices with the same address

I'm a teacher of a secondary school in the Netherlands. My students are working on a sun sensor placed on a moving object, with which the attitude w.r.t the sun is determined. A couple of ambient ...
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Getting an ACK failure right away after writing slave address in interrupt mode for I2C [STM32F4]

I see that once slave address is written in the interrupt handler, I get an ACK Failure right away, but when I do the same thing with polling approach, I do get an ACK and goes on to read off the ...
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Do I need to pull up the I2C voltage to the VCC of a ADC?

I am planning to use LTC2451 which is a ADC with I2C interface. The main bus voltage that supplies the LTC2451 & the MCU is 3.7V and the GPIO voltage of the MCU is 1.8V. Is it safe to pull up ...
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How does i2c standard or fast mode effect the output data rate of the sensor?

I am using BNO055 motion sensor supports standard mode 100kHz and fast mode 400kHz but sensor specifies following Gravity Vector 100Hz Euler Vector, 100Hz Quaternion, 100Hz Magnetic Field ...
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BQ34210-Q1: Battery data needed to configure fuel gauge without dedicated tool

I have a BQ34210-Q1 on a custom board with a CC2652R. I'm trying to get the StateOfCharge and StateOfHealth from this battery I tried reading the technical manual and the datasheet and got to the ...
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Is it possible to Extending I2c without twisted pair?

I need to extend I2c bus in a multidrop manner through long cables, I have found many ICs / extenders but they use differential signals where twisted wires are must, Is there any other way to extend ...
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Can twisted pair replaced by two wires which are closely placed?

If I have differential signal wires, can I place two wires closely 1mm-2mm gap between them but not twisted? (1mm or 2mm gap is fixed it won't change from place to place ) I am using Differential I2C ...
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Is it possible to use i2c accelerator to multiplexer input?

I have 10ft long wire cabled i2c 4 buses (for 8 sensors, sensor are not in the same place each has 2 i2c addresses), I try to use i2c multiplexer PCA9548A with an i2c accelerator Ltc4311, i2c ...
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Noise suppress recommendation and best practices

I've developed for my home automation project this schematic: it's quite simple, an ESP32 GPIO enable pin drives those mosfets that gives power to the LED and enable the PCA9306 EN pin, for more ...
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TLC59116 will not drive LEDs

Having the hardest time with this TLC59116 LED Driver IC from Texas Instruments. I have done a crazy amount of debugging and still cannot get it to drive a single LED. I have followed all the ...
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How do I use those digital LEDs with an I2C device?

I want to use the MMA8453Q accelerometer via I2C while at the same time sending data to some WS2812B-2020 digital LEDs. I am thinking of using the PIC16F1789 microcontroller. Since I can't hook the ...
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I²C Slave Reset routine

UPDATE: Code snippet already done below. Not sure if correct. I implemented the routine which is found in Microchip's datasheet in order to reset the EEPROM memory (24LC512)in case it hangs up. But ...
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I2C Interface is not working on STNRG388A

I am trying to communicate with MAX30205 using STLUX385/STNRG388A. I'm using STM8S standard peripheral libraries to communicate with I2C bus. For STNRG388A device drivers, I'm using STLUX385 drivers ...
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How to set the resistor value for INA219

I managed to understand how to write/read data from the INA219 directly, using just linux/i2c-dev. When I was planning my PCB and Bill of materials with my supervisor he suggested I should use a 0....
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55 views

Is there any benefit to using twisted pair for short-distance I2C?

I know twisted pairs are important for differential signals, which I2C is not. I also know I2C is not intended to be used over long wires. However, I made a design where I need to use a cable to ...
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39 views

clock period, throughput and efficiency of I2C bus

If a I2C bus is runs at 400kHz what is the clock period ,data throughput in data-bits/seconds and bus efficiency? i am very new to those buses and is the clock period is 2.5 micro seconds ? any help ...
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Long Range Bus for Raspberry Pi

I wish to measure the rotational speed and electrical current used of/by industrial components. Those components are driven by strong electric motors. The solution should be cheap and fast to ...
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65 views

Sensor 30 meters away

for my home automation project i'm using 10 Sensirion SHT21 Temperature and Humidity devices, those devices are distant 30/50 meters away from my ESP32. Those devices are driven using 5V and at both ...
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what is status code “0xC8” in an AVR TWI MCU I2C

0xC8 is called Last data byte status in Atmel's TWI's Slave transmitter mode, but what does it really mean? If TWEA==0 is for the Master receiver, then a Data byte in TWDR has been transmitted; NOT ...
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Will this design for an XHP70.2 LED Driver with arduino control work to the params specified?

I am making a driver PCB to drive an XHP70.2 LED at 15A (~7v) Continuous, Controlled from an Arduino. I am new to OpAmp's so I would like to know: Does this circuit look as though it would function ...
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Addressing individual distributed RGB LEDs

I want to have a set of RGB LEDs and to be able to define the color for each one individually. The LEDs will be in different locations but in the same room. Some solutions I'm considering with wired ...
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Odd waveform with I2C setup

In the image below the circuit sometimes works perfectly, but sometimes the SDA and SCL lines appear to be pulled to a middle voltage value rather than Vcc and GND. Also, this circuit works when ...
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SSD1306-based OLED display E/RD# and R/W# pins

This is the OLED display in question and this is the datasheet of the display. I am going to connect to it using I2C. The datasheet provides mostly understandable explanations for the pins as far as ...
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Boot problem with STM32 HAL, I2C HDD44780 and 1602 LCD

I'm using the following (relevant) combination: STM32F103C8T6 devboard (bluepill) 1602 LCD with I2C (HDD44780) STM32CubeIDE HAL Also I have a keypad and some other components attached, but these are ...
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Writing I2C library - Philips trademarks

I guess is a very trivial answer for many but I am not sure in my case. I am writing an open-source firmware, which might also get documented and commercial use is not excluded from who is using it. ...
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Application doesn't work normally after initializing I2C in the bootloader

I am working on STM32F756ZG. I have a bootloader at 0x08000000 and application at 0x08040000. The bootloader and the application both use I2C protocol to store a few configurable parameters to the ...
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ESP8266 access MPU 6050 return error

I asked the question https://arduino.stackexchange.com/questions/72642/esp8266-not-working-with-mpu-6050-over-wire-library-and-i2c and https://arduino.stackexchange.com/questions/72665/esp8266-...
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Is there a way to use the i2c interfaces on a standard PC mainboard to control a device?

I have attached a few sensors and an LCD display, all of them having an I2C interface, to my raspberry pi, and written a software on the pi to read/write them. Right now, I have a network daemon ...
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What factors does the set-up time and Hold-time for an interface IC depend on?

I have working with EEPROM and QSPI Flash ICs. They have this electrical parameter called as Setup time and Hold time. I know we must not violate this in order for proper communication. But my ...
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Wire.endTransmission(); have trouble ending

I am trying to read data from an INA219. To save some memory, I looked at the .cpp file from Adafruit_INA219 library: (Adafruit basically used their function wireWriteRegister(0x05,cal);) ...
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Different pullup resistors on the same I2C SCL and SDA before and after a I2C repeator hub

My Environment: STM32L476RG RTOS: Zephyr 2.1.0-rc I2C device: AQM0802 (character display 8x2) I2C device: MLX90632 (FIR thermometer) with 1k pullup resistors Problem I am trying to use the AQM0802 ...
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How to wire 0.91/0.86 inch display to i2c?

I have a 0.91 inch display with a 4 pin I2C connection. I then realised that I needed to use a 0.86 inch display with the connector in the above image. I have searched on google on this but nothing ...
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Difference between I2C STM32 HAL functions

I'm using I2C in a project on STM32, and i was wondering what's the difference between HAL_I2C_Master_Transmit and HAL_I2C_mem_write, and the difference between HAL_I2C_Master_Receive and ...
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I2C Master: How to read with repeated start condition?

I have a PIC16F18875, on a board where it is configured as I2C master. 7 bit addressing, 100 kHz clock Several different I2C slave devices are on the bus. am using MPLAB X IDE with MCC plugin using ...
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Slow FIFO read from LSM6DS3

I have been trying to read FIFO buffer from LSM6DS3 inertial sensor via i2c. The processor will read LSM6DS3 buffer every 20s so the FIFO will contain approximately 3120 bytes of accelerometer data. ...
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What length wire and how many devices after which I need a repeater or extender for i2c?

I am using an ESP32, which has two i2c buses. I am thinking of adding multiple devices to each bus (a total of 20 devices, 10 devices per bus). The maximum length of any device on a bus from esp32 ...
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What happens if too many devices connected to multiple i2c buses on ESP32?

See this diagram: In the above diagram, multiple devices are connected to a single i2c bus. In my previous question, I was wondering what would happen if there are too many devices on a single i2c ...
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How to determine number of devices that can be connected to 3v3 pin of ESP32?

I am not an electrical engineer. I’m experimenting with an ESP32 Dev Kit. I was looking at this image: I had a couple if questions. In this diagram, there are two devices connected to the 3v3 pin. ...
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Issues reading from an I2C device

I'm testing out the BQ25887 2 cell balance charging IC, and I'm trying to read the data from the I2C interface. But I'm not getting any results. I am unable to see any values from the serial monitor ...
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Do chained I2C address translators also act as buffers?

I'm working on a data collection/testing setup for multiple pogo pin test PCBs (~10 max per master) connected over I2C, daisy chained together. The design is based around the AD5593R ADC/DAC/GPIO chip,...
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I2C clarification

This question is mainly to check if I understood i2c protocol and hardware correctly. Because pin modes confusing me a little, ia m jsut a beginner. I2C SDA and SCL lines are pulled high with pull up ...
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Swapping out RJ-45 connector on Differential I2C circuit

I'm trying to use Sparkfun's Differential I2C Breakout circuit into my own design, and I'm looking to replace the RJ-45 connector. It's too big (having a footprint size of 15.24 mm x 15.24 mm), and I ...
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what is I2c address of BNO055?

I made a custom circuit with bno055 it shows i2c address 0x70 is it possible? I used the Arduino i2c scanner. I am not getting any data aswell nothing else is connected to Arduino nano board as well,...
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MCP2221A Sending Register Address

I am trying to control 2 IC(PCA9555) via i2c. The i2c lines can be accessed by a connector. Also i have a usb connector and it is connected to a mcp2221A. The MCP's i2c pins are common with the ...
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240 views

SDA pin on I2C lines seems weird

I am trying to analyze the I2C commands sent by a PC software to R3910 DSP chip The software uses a programming box (provided by the same company that manufactures the R3910 chip) to communicate ...
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I2C Level-shifting? 2N7002DW

Can someone explain this IC? It seems to be a two-way n-mos (has two circuits in one). I have a master device that runs on 5V and multiple slaves that run at 3V3 and they communicate via i2c. Why ...
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How does an Intel processor “talk” to an I2C device?

I don't come from an Electronics background, so please bear with me. Assume an Intel processor wants to talk to a temperature sensor over the I2C bus. How does the underlying communication look like? ...
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What is the difference between SDA protocol and I2C?

A manual for Sound Design Technology's "DSP Programmer" programming box has the following statement: Hearing aids based on the Sound Design Technologies Wolverine platform can be programmed ...
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What is XCLR and EOC

As the title says, looking at IC9 (BMP085), could someone explain why XLCR and EOC are connected to P-XCLR/P-EOP and why there is no other match in the schematic? Are these connected at all? If not, ...

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