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

2
votes
2answers
231 views

Make Arduino and 89C52 talk to each other

I am trying to create a project in which I am required to make Arduino and Atmel 89C52 talk to each other. I know this can be achieved via UART but the problem is my Arduino is already using its ...
0
votes
1answer
58 views

U(S)ART/SPI/I2C - any common/prevalent/recommended connectors?

Good morning everyone! I'm currently building the board with the STM32F417 microcontroller, and I want to have separate (out-of-GPIO) I2C, SPI, UART and USART outputs on the board. But I'm lost on ...
2
votes
1answer
52 views

Communicate with 3 Sensors with the same I2C address

I got three sensors stick from sparkfun : https://www.sparkfun.com/products/10724 which each one got an arduino pro mini that filters the data before to send to a main Arduino. Like this: and ...
0
votes
0answers
23 views

PIC32 and I2C EEPROM interface problems

I am writing code for a PIC32MX250F128B to interface with the Microchip 24LC02B EEPROM with I2C interface. I have followed the datasheet of the EEPROM, the PIC32 and section 24 of the PIC32 family ...
1
vote
0answers
49 views

Waveform decoding

I am trying to get the information from my mouse's optical sensor, strictly ΔX and ΔY. I looked up the datasheet for the microcontroller that communicates with the optical sensor and all I could find ...
0
votes
5answers
180 views

How many i2c slaves can a i2c master support?

Is there a maximum number of i2c slaves that a i2c master can drive? What are the physical limiting factors?
0
votes
2answers
65 views

Why does the I2C interface use the open-collector/open-drain?

The open-collector adds inconveniences like requiring an external pull-up resistor and slows down the throughput. Why did the I2C designers choose to use open-collector/open-drain?
2
votes
3answers
369 views

Why are pull-up resistors required to be connected to the 2 lines of I2C? [duplicate]

Without pull-up resistors connected to the 2 lines of I2C, I2C communication fails. Why is there a need to have pull-up resistors for I2C? In contrast, UART and SPI do not need pull-up resistors. ...
2
votes
2answers
60 views

Not getting correct values in I2C interfacing in Atmega

I'm very new to the concept of I2C and I've been having some problems interfacing I2C between 2 Atmega32(s). I have one Atmega32 as a Master to which an LCD screen is connected and another I2C as a ...
0
votes
2answers
111 views

Arduino interface with I2C Pressure Sensor

I have a Honeywell ASDXRRX100PD2A5 I2C Pressure Sensor that I want to read using an Arduino. Looking at the datasheet, I know that the I2C address is 0x28, and I have had a play with bits of code ...
0
votes
0answers
38 views

Pic24F: #define I/O pins?

I am trying to #define Pic24f I/O Pins with user defined Name. here is the part of my code : ...
0
votes
0answers
21 views

Software I2C - Atmega8 [migrated]

I am using Atmega8 with 12MHz crystal, on my breadbord. I can use SDA and SCL pins with default arduino library wire.h, and it works. But I want another pins to use I2C protocol. I tried library, ...
0
votes
1answer
93 views

PIC24f: How to Generate Start condition using SPI for I2C device?

I am trying to communicate with the device having internal communication as I2C while externally it has two different pin for Input & Output along with a separate pin for Clock. Here is the link. ...
0
votes
1answer
46 views

Shift registers, flip-flop, Multiplexer & Demultiplexer with microcontrollers utility

While i read alot about the popular 74HC595 shift register and its use for multiplexing i can't find anything about the following chips: MC14053B Triple 2−Channel Analog Multiplexer/Demultiplexer ...
3
votes
2answers
54 views

Use GPIO for switchable Pullups of I2C

I'm designing a general purpose interface board and want to make available as many of the peripherals available and usable on an expansion header without the need for permanent (soldering) changes. ...
0
votes
1answer
23 views

does CompactRIO modules have builtin pull-up/down resistors

I have Compact RIO 9076 with 4 different modules: ni-9205 (Analog Input), ni-9264(Analog Output), ni-9402 (Bidirectional Digital I/O), ni-9403 (Bidirectional Digital I/O). I have several 3rd party ...
0
votes
1answer
50 views

I2C - addressing

In the i2c protocol, I would like to know how the slave & master address are assigned. Most of the internet doc talk about how the protocol work, but i wasn't able to find doc about i2c slave ...
0
votes
2answers
45 views

Which bus is it necessary to use and where can I find it?

I'm trying to make a tiny navigation system with 6 IMU sensors. The main requirment is accuracy and distance between sensor and master. Now in prototype I use I2C, but the length of wire connecting ...
0
votes
1answer
72 views

Why does I2C look like this?

I'm trying to debug an I2C device, and the wave is looking really weird. Why is it curved?
2
votes
2answers
65 views

I2C -internal and external pull up

I have a doubt in I2C pull up resistor. Actually I am developing a I2C module using GPIO pins. I have used external pull up resistor(10k) for the SDA and SCL lines. Do I need to enable the internal ...
0
votes
0answers
63 views

I2C read operation doubts

I am trying to read the 16-bit data from a location in EEPROM using I2C bit banging. Viewing the oscilloscope, the write operation seems to be correct. However, the read operation does not seem to be ...
0
votes
2answers
75 views

I2C on atmega168/328 using interrupts

I have the following I2C configuration with an ATmega168 (1 MHz) as the master and an Arduino Uno (16 MHz) as the slave. The command for the LED connected to the slave comes from the master and ...
1
vote
1answer
45 views

How do i turn multiple usb ports off based on multiple sensors

I'm looking for a way to turn a usb port on an off from an Arduino, I'm looking at purchasing something like this and somehow using a pressure or light sensor to turn the usb port on and off. I was ...
0
votes
1answer
133 views

Using GPIO pins as software I2C pins and finding analog value of those pins

I am using AT32UC3C microcontroller which has 64 pins. I am using gpio pin PB01 as SCK and gpio pin PA04 as SDA and ticking then manually high and low. These pins are configured as GPIO_OPEN_DRAIN and ...
0
votes
0answers
29 views

I2C Display Module (NHD-C160100-DiZ) for DIY Scientific Calculator Help

Good evening everybody reading, This is a project I've been developing for about 6 months. I am stuck because I can't get the display module (datasheet here) to work. I attached my schematic for the ...
3
votes
3answers
185 views

Using I2C and SPI communication on the same same clock and data lines

I am using a PIC18F25K80 with multiple slave devices. All of them uses I2C except one. What i want to know is that can i first use I2C with the devives that uses I2C and then close I2C, change clock ...
0
votes
2answers
36 views

How to program via ICSP when chip is in-circuit with interfering chips?

My Circuit is: USBTinyISP <-usi/icsp-> ATTiny85 <-usi/i2c-> MCP4725. That is, the USI pins used to program the t85 are also used for i2c in the final circuit. When I try to flash-program the ...
0
votes
1answer
73 views

I2C-to-SPI bridge and SD card

I am using a PIC18F25k80 microprocessor, which is communicating by using I2C protocol with peripheral ICs. After collecting the data from the ICs I want to store them in an SD card. However for the SD ...
0
votes
2answers
101 views

How to correctly wire an interrupt pin, clock pin, PWM pin, SPI pin

I've a question about how to correctly wire some microcontrollers pins. In particular: Interrupt pin on microcontroller (pull up/pull down resistor and with which value) Output clock pin from a ...
-1
votes
1answer
45 views

I2C programming ATTiny88

I am beginner at programming uC's. I have read all the tutorials on what is I2C and how it works, but I couldnt find any help specific on how to create a connection between my sensor and ATTiny88 ...
0
votes
1answer
67 views

Running Bus at Low Speed- I2C bit banging

I am implementing I2C using Bit bang. The slave can accept maximum baud rate of 400kbps. Iam not using external pull up, which is required because of which the fall/rise are not accordingly. I read ...
0
votes
1answer
99 views

Arduino UNO + PCF8574P + 4pcs HC-SR04

I'm trying to connect 4 ultrasonic sensors HC-SR04 to Arduino UNO using a NXP's PCF8574P chip. If 4 sensors are connected to Arduino pins, everything's fine. The problem appears when I try co bind ...
15
votes
7answers
2k views

Why is serial EEPROM preferred over parallel EEPROM?

In the wikipedia page for EEPROM: http://en.wikipedia.org/wiki/EEPROM it is given that "Parallel EEPROM devices typically have an 8-bit data bus and an address bus wide enough to cover the complete ...
0
votes
0answers
44 views

What registers should be written first in mpu6050 to read the data of gyro registers

I have mpu6050 interfaced to 8051 micro-controller. I am using this to balance my quadcopter. I googled very much but I did not find how to get value of gyro or accel, every where i found is that it ...
2
votes
1answer
69 views

PIC16 I2C interrupt does not occur if serial port enabled

I'm using a PIC16F1825 mid range PIC and I've used it with a UART and SPI for a good while without issues. When I added code to handle I2C (instead of SPI - it's either one or the other on this PIC) I ...
1
vote
1answer
56 views

I2C - bit banging query [duplicate]

When bitbanging I2C, rather than switching the LOW/HIGH states of the pin, switch between LOW/HiZ by simply altering the DDR/DIR registers.Why is it like this? Why can't we switch LOW/HIGH states of ...
0
votes
2answers
99 views

I2C baud rates and delay calc(bit banging)

The microcontroller which I am using doesnot support I2C hardware. So,I am trying to implement I2C in the module using GPIO ports. The microcontroller communicates with EEPROM, and the EEPROM has SDA ...
0
votes
2answers
88 views

What is the difference between the I2C interface and the “Grove” system?

The Grove system has various sensors and boards that to me all appear to be I2C-based, with a standard connector shape/size added to them - however I am not sure if this is exactly true or not - is ...
1
vote
2answers
64 views

I2C EEPROM endurance

I am using an AT24C32 I2C EEPROM device as a simple storage unit for recording slow analog voltages. I am writing the data byte-wise, no pages. Every write cycle takes 10ms to complete. The data ...
1
vote
3answers
60 views

What makes cables suitable or unsuitable for a given purpose?

I've been working on a homebrew set of VR Goggles w/ head tracking, and am just beginning to plan the cable that will connect the parts on the user's head to the electronics on the main unit (which ...
0
votes
1answer
72 views

Motor noise interfering with I2C

I built a robot using the Arduino Due with all the sensors running at 5V over I2C. There is a level shifter on both I2C lines. The motors are controlled using a VNH5019 motor driver carrier from ...
1
vote
2answers
138 views

I2C Module Not Responding

I am writing a basic I2C slave as part of my code on a 20-pin 8-bit PIC16f MCU. As best as I can tell, this microcontroller has a module that watches the I2C bus and only updates my registers if there ...
0
votes
1answer
47 views

LSM303DLHC outputs frozen

I've was trying all afternoon yesterday to get some data out of my LSM303DLHC using an STM32L152 Nucleo board. Finally I got all the I2C stuff down, managed to set some registers, verify their ...
1
vote
1answer
131 views

Getting gyro values from MPU-6050

I have an MPU-6050. I have known that it uses I2C bus for communication, but I have no experience of the I2C bus. I know that SDA and SCL serial wires are used in this communication. I have got ...
3
votes
2answers
105 views

How come the decoder gives a question mark?

I'm using a scope to debug I2C (bit banging) by letting it capture the signal. I think that the output should be good, but the scope's decoder gives the following: where there is a question mark ...
0
votes
2answers
44 views

Does each I2C START signal need to be closed by a STOP signal?

Could two I2C START signals be sent one after another without a STOP signal sent in between? Below is an example of bit banging, where there is not STOP between the first and second START: ...
1
vote
2answers
59 views

Why does the clock stay at high?

I'm very new and I'm trying to do an I2C trace of ADXL345 with Ch1 to SCL and Ch2 to SDA, but the traces look like these: Is the clock not supposed to oscillate continuously? Is it normal for it ...
0
votes
0answers
30 views

Systick Timer problem

I am trying to use the systick timer to update a variable which stores millisecond elapsed on a STM32F051 in Coocox ide 1.7.8 . I also want I2C and UART communication in my project. I managed to get ...
1
vote
1answer
116 views

Why is my SSD1306 OLED only displaying half of the screen area?

I am trying to get this display working with my arduino via i2c: http://www.buydisplay.com/default/0-49-inch-oled-display-module-64x32-pixel-ssd1306-i2c-white-on-black I have successfully initialized ...
0
votes
1answer
21 views

ad5359 address not shown

I am working AD5259 , its a digital potentiometer. Its connected to i2c bus on raspberry pi. But the address of device is not shown. Datasheets says its 0X18. I guess the device does not respond to ...