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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I2C- Not reading after proper write

I want to ask in general, Is it possible that in I2C write operation, after getting acknowledgment for each byte written, still it is not written in the location? Because in my case I am able to get ...
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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 ...
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Simple and cheap PIC controller with two I2C buses [on hold]

I'm looking for a simple and cheap PIC controller (or alternative) that has two independent I2C buses. So far all my Google search has failed. The existence has been been mentioned in an other post ...
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51 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 ...
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2answers
59 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 ...
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41 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 ...
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1answer
108 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 ...
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19 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 ...
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57 views

How to check if eeprom is corrupted or not? [closed]

I am writing a program to write some values to the addresses of the eeprom and write automatically write zero to the left addresses but it is not working correctly.... It writes some garbage values. ...
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3answers
141 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 ...
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2answers
31 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 ...
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50 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 ...
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2answers
84 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 ...
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1answer
40 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 ...
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1answer
64 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 ...
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1answer
69 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 ...
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80 views

I2C - Timing mismatch

I am trying to implement I2C module in my controller using bit bang. But the slave didnt acknowledge the address. I am sending the correct slave address, and I can view this in Logic Analyser. Further ...
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67 views

I2C- slave not acknolwedging

I am implementing I2C using bit banging. I am able to write slave address, but slave is not acknowledging the same. I have some doubts below regarding this: According to datasheet, the slave address ...
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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 ...
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33 views

Temp/Humidity Sensor I2C

I am trying to use a HTU21D sensor with a Pic18FXXXX micro controller, the communication is done through I2C. I have been having difficulty with getting it to measure; I can get the sensor to write ...
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30 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 ...
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1answer
52 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 ...
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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 ...
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2answers
81 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 ...
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77 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 ...
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2answers
60 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 ...
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3answers
53 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 ...
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1answer
56 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 ...
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2answers
125 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 ...
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1answer
39 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 ...
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1answer
79 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 ...
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98 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 ...
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41 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: ...
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2answers
57 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 ...
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19 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 ...
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1answer
98 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 ...
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1answer
20 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 ...
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1answer
74 views

Xmega128C3 TWI read error

I'm interfaceing an Xmega128C3 with MMA8451Q acceleration sensor via i2c. I was able to initialize the accelerometer, I checked every transmission on oscilloscope, it was done properly. The problem ...
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57 views

PIC18: I2C with external triggered interrupt stuck in ISR

I am trying to implement a simple, external, pushbutton trigerred I2C communication between a PIC18F46K22 and a ST LSM330D MEMS sensor. I tried to find straightforward libraries for the easy ...
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1answer
45 views

Protecting I2C bus with diodes

I'm trying to add some protection to an I2C bus, and keep getting an unexpected result. simulate this circuit – Schematic created using CircuitLab In principle, I'd expect this to clamp ...
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51 views

reading temperature from ds1621 using stm32f4 discovery

I am trying to use the stm32f4 board to read temperature from a ds1621.As mentionned in the data sheet ,it uses i2c protocol. I implememented this code based on what i found on the net. My problem is ...
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234 views

Does the STOP condition have any meaning on a single master I2C system?

I'm currently working on rewriting some of the code on my I2C driver, and I'm trying to figure out the exact purpose of the STOP condition. I believe that on a multi-master system, once a START ...
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3answers
114 views

I2C and SPI on the same bus

I have already configured an I2C protocol between a master device (PIC) and two slave devices (sensor ICs). After obtaining the measurements from the sensors I want to store them on an SD card. For ...
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9answers
2k views

Why does I²C only have pull-up resistors (interview question)?

The interviewer wanted to know why pull-up resistors are used on SDA and SCL when the opposite logic can also be implemented. Is there an explanation for why pull-up resistor usage is the chosen ...
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3answers
64 views

I2C SoC explicitly not multimaster

While reading the guide of a chip I'm about to take in use (Intel Edison), I noticed the SoC is specifically not supporting multi-master. The SoC is always I2C master, it does not support ...
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75 views

High pass filter for I2C

I am building a gimbal and passing I2C through sliprings. Right now I have 1.6Vpp spikes at about ~32kHz on the i2c bus. (The spikes are harmonics from motors which are driven at 16~17kHz). The i2c ...
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1answer
50 views

toggling a pin using the hardware compare feature of timer1 AVR

This link - says: "In CTC mode, you can also trigger interrupts, but it is also possible to not use interrupts and still toggle an output pin. Using it this way, the functionality occurs ...
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117 views

I2C: How to connect Raspberry Pi (power cut) to ATmega328p

I would like to interface a Raspberry Pi with an ATmega328p microcontroller using the I2C bus. These two parts act both as masters, but not at the same time. The Raspberry Pi is powered through the ...
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2answers
93 views

What are the address input pins used for in ds1621?

I just bought a ds1621 temperature sensor and started reading its datasheet. I found out that it have 3 pins (A0,A1,A2) which as specified in the datasheet are chip address input. Can somebody ...