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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STM32F103C6 doesn't go out of a condition when it send data through I2C in proteus using HAL libraries

First of all, I don't have any STM32 physical device with so I'm working through simulations with Proteus and STM32CubeIDE. Following with the question: I'm simulating an STM32F103C6 as a slave and ...
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55 views

I2C Address 0x00 not supposed to be showing up

I am currently trying to check all the sensors on my PCB with an I2C scanner to see that they all acknowledge. One of my coworkers had it over the past week and dropped it. When it was given back, ...
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Would bypass capacitors of a voltage regulator which powers an I2C device and the bus cause issues?

I'm planning on powering a 3.3V I2C sensor and its pull up resistors with a linear LDO regulator. http://www.farnell.com/datasheets/2108564.pdf The output of the LDO aswell as the sensor's power pins ...
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Problem in editing EEPROM of MLX90614ESF sensor , pic 18f4620 , I2C communication

I want to edit Tomax and Tomin in the EEPROM 0x00h and <...
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25 views

SC18IM700 operation (RS485 to UART to I2C)

I need to create a circuit to talk to a piece of equipment using the I2C bus. I'm on a PC that has an NI serial card with RS485 ports(I'm not sure of the model number off the top of my head). I ...
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Control register of magnetometer in MPU-9250 reseting itself

I want to read magnetometer outputs from the MPU-9250 sensor (Datasheet, Register Map) but the CNTL1 Register (0x0A) of the magnetometer resets for certain values. I configured the sensor properly so ...
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25 views

Attiny88 as I2C gpio expander - analogRead and digitalRead functions do not work

I am working on making a system that has two PCBs mounted atleast 30 cm apart (but not more that 50 cm). The first PCB is the master and the second is the slave, both these have analog and digital IOs....
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54 views

Interfacing I2C with Siemens PLC [closed]

I have a Siemens S7-1200 PLC. Is there a good way to interface with an i2c sensor? I found that SIMATIC IOT2020 has an i2c extension board. But then I don't understand how to interface the SIMATIC ...
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ATMEGA128 & AD7417 Reading first channel using external reference voltage

I'm doing test work in Proteus ISIS. Where in circuit used External ADC, but there is no modeling module in the proteus. And i can't test it. This ADC using TWI(I2C) interface. ADC connection circuit: ...
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63 views

I2C master's output is always 255

We are using two Arduino UNOs as a master/slave for this I2C protocol. We used the first Arduino (slave) as a sensor that will input dummy data (in this case, temperature data). The Arduino (master) ...
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26 views

si7060 I2C temperature sensor with STM32 CubeIDE?

I am trying to read an SI7060. It's my first time using i2c and it doesn't seem to work. Do I make something wrong here? SI7060 datasheet ...
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37 views

Why would using full buffers cause problems?

When reading docs on Smbus2, a Python i2c library, I found this statement: It is possible to write 32 bytes at the time, but I have found that error-prone. Write less and add a delay in between if ...
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If there is a cable and jack standard for I2C?

I want to do a connection of multiple current and voltage meters, they connect by I2C. Is for to monitor solar panels and batteries, they will be a considerable distance from the master. I thinking ...
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How do I figure the I2C timings for a peripheral?

The I2C timing specs are confusing me a bit. Here's a few timing characteristics from my peripheral : It's basically the same as I2C timing specs provided by NXP. I am looking at specs at 100khz mode....
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51 views

Does Slave Select have to be sychronous with Clock?

I'm working on the SC18IS600 chip (SPI to I2C converter) and have been having issues just communicating with it. At the moment I am attempting to configure the I2C Address register and set it to 0x3F ...
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58 views

I2C bus for real-time communication

I'm working on a distributed real-time application, where 4 MCUs (PIC18F45k22) are connected to a network. The real-time kernel FreeRTOS is running on each of the four PICs, and all MCUs exchange data ...
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I2C not working unless its through a mosfet (not level shifting)

Ive been dipping my toes into the world of hardware over the last year and I'm working on a project that i've been stumped on for a few months now. I've made progress on alot of roadblocks but this ...
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Reading Humidity Sensor Measurement via I2C

I have a Honeywell humidity sensor which communicates with a STM32F4Discovery microcontroller. In this following datasheet, it is written, that to start a measure cycle, first a write bit (0) must be ...
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43 views

PIC16F877A I2C MSSP not sending data

Sup, guys. I'm in the violent war with PIC MCUs and they're clearly winning, so I'm asking once again for your intellectual support. I have PIC16F877A on a breadboard, external 8Mhz+2x20pf, bypassed, ...
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55 views

Adding a callback for processing the UART data seems to cause issues with I2C interrupts

So I wrote peripheral drivers on STM32 and wrote a simple application to read the user input via terminal and respond accordingly. I am using interrupts for both UART and I2C but the way I previously ...
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ADC IC I2C problem

I'm trying to run ads7924 using stm32f series. But i2c does not work so I check the i2c line. Between 0R, MCU side 3.3V but ads7924 side 0V. I set pull up setting of MCU internally . What is the ...
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73 views

Gain on an ADS1115 using differential input

I'm using an ADS1115 hooked up to a Raspberry Pi to detect a differential voltage of about 0.5V. VDD is connected to the Pi's 3.3V, GND to Pi Ground, SCL and SDA to their corresponding Pi pins. I then ...
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36 views

How to estimate I2C bus capacitance?

In my current project, I need a microcontroller to retrieve the temperature of 60 temperature sensors which are located on the same PCB with distances not exceeding 50 cm. The temperature sensor's ...
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36 views

Timing specifications in a communication protocol

I am having this I2C EEPROM Chip from Onsemi - CAT24C In table 6, AC Characteristics of the datasheet, only the Minimum time is provided for the SCL clock low and high period. My questions : Not ...
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How many devices can be daisy chained via SPI/I2C?

How can we determine how many devices can be daisy chained from a datasheet
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How to detect in the code (Not have to design any extra hardware) if a (peripheral) PCB has been inserted/ plugged/ interfaced to the main PCB?

I have a main PCB with a microcontroller on it with lots of connectors on it to connect to many other (peripheral) PCBs which have sensors and report data to the MCU on the main PCB. I wanted to ...
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PCF8574 and OLED SSD1306 I2C conflict

I have a ESP12 module which is connected to multiple I2C devices such as an 24C08 EEPROM, DS1307 RTC and a PC8574 expander. Everything works fine until I decided to add an OLED module to this setup. ...
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32 views

Connect an I2C camera to computer via USB as a webcam

I took out of an old security camera its circuitry and I am trying to figure out a way to connect it via USB to my computer and use it as a standard webcam. Is it possible? Here are the front and the ...
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RTC not Responding

I'm using a MCP7940 with a Atmega328P on a custom board. I'm using the Arduino Wire library. When I first start communication to write the time to the registers, things seem to work fine but then in ...
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Simulation / Emulation of an I2C EEPROM MEMORY (M24LC16B)

I'm using iBurner3.2 I2C Bus EEPROM Programmer to write and read from an I2C EEPROM MEMORY (24LC16B) using COM Port, I want to simulate the behavior of this specific I2C EEPROM, is there any software ...
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105 views

How to debug this I2C hard fault?

I am using an STM32F103C8T6, STM32CubeIDE with HAL. During accessing an LCD (1602), with I2C, I get a hard fault. I try to debug it, but somehow I don't see the stack. See the following screenshot: ...
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62 views

Additional Voltage on I2C Bus

I have redesigned one of my boards to the ICM-20689 (datasheet) instead of the ICM-20789 because of a voltage issue that I previously had. Link to previous issue. A little background on my setup. The ...
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61 views

I2C single-master: Does the master have to implement repeated start?

I am implementing a minimal I²C master, trying to keep it as simple as possible (but as complex as necessary). This master is a hardware peripheral - you could consider it part of an FPGA design, ...
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How is clock bus different than peripheral clock in STM32?

Been looking to clarify this confusion: how is the clock that a specific peripheral is on (APB1, APB2 etc) different than the peripheral clock itself? Say, I2C1 ...
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49 views

Unable to communicate with LCD2004a via I2C (Nucleo-F103RB)

Hell guys, i'm trying to communicate with LCD2004a with the I2C extender. i followed this guide: https://www.youtube.com/watch?v=7mQppaEJjT4 what i did: I generated project using CUBEMX to Keil ...
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What is Bus capacitance in I2C? How it limits number of devices can be connected to the bus?

Bus capacitance limits number of devices that can be connected by I2C. What problem is encountered if one tries to exceed this limit can anyone explain this in detail please. Thank you
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75 views

What is the meaning of “400 kHz when other system delays permit?”

I am going through the datasheet of the P82B715 I2C extender. The datasheet says "400 kHz when other system delays permit." What does this mean? (In the Texas Instruments datasheet they do not ...
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I2C PIC32 ack not recognized - solved

Edited solution: There are 1k8 ohm pullup resistors on the Curiosity board and there are 4k7 ohm pullup resistors on the trackpad which will give a total pullup resistance of ~770 ohm at max which is ...
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Same i2c devices on one multiplexer pin

I have an arduino with a multiplexer for i2c expansion (I have multiple same boards exceeding its adress range) where every pin leads to separate sensor box. My question is: is it possible to put ...
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53 views

understanding TWI

I'm working on a school project where I have to interface an external ADC with a Digilent Nexys4 DDR board FPGA. The instructions are given in the following picture with a schematic of the simulation ...
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46 views

I2C concept and Working

I'm working with I2C and I have been using python library to communicate with a magnetic sensor. Now I am working with a different chip and it makes me wonder if I get the right concept or not. The ...
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74 views

STM32 I2C only sends address

Hello I am trying to communicate with TI BQ28Z610 by using Nucleo-F746ZG. All I do is trying to read data from TI chip. I am sending 0x08 to slave address 0x55.I2C frequency is 80kHz and pull ups are ...
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27 views

Max speed of communication between the switched device of I2C switch IC

I have a I2C switch PCA9546 that lets me connect I2C devices with the same address to a host device. My slave and host device can go up to speed of 1 MHz, but I do not know if the switch allows for me ...
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40 views

Getting a NACK after reading 1 byte from MCP9808 temperature sensor

I am implementing drivers for I2C interrupts for STM32F401RE and looks like the API for transferring the data seems to work. But for receiving, I see that I'm only able to receive one byte. I am ...
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Does Linux regmap handle repeated start/stop i2c transaction?

I'm bringing up ADV7610 on Linux Kernel v4.14 on TI AM5728 platform. The Kernel module for this device is failing to successfully probe the device: ...
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44 views

What process detects whether two I2C master devices send conflicting messages?

I'm curious - if two I2C master devices are sending commands or messages at the same time that conflict, is there any process that detects it ? What does that process do ?
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i2cget works, but i2cdetect does not show the device

I'm working to bring up ADV7610 (similar to ADV7611) on a Linux based embedded system (TI AM5728 platform). By all account, I think the Chip-Select, Reset and I2C bus are all configured correctly. ...
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71 views

What is the meaning of Angular Velocity Vector 100Hz of BNO055?

I am using an Arduino Nano with BNO055 Adafruit library. The I2C speed is 400 kHz. The Adafruit BNO055 Absolute Orientation Sensor mentions Angular Velocity Vector (100 Hz). What does this 100 Hz ...
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61 views

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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100 views

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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