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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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29 views

Which protocol is best suitable for communicating with motion sensor IAM20680 [on hold]

We have a requirement to implement an algorithm to detect “Harsh Acceleration & Sudden Brake” in one of our projects. For the same, we using Invensense IAM20680 6-Axis MotionTracking Device (...
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1answer
58 views
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VL6180X ALS values soo small

I have bought VL6180X proximity sensor on breakout (Aliexpress) originally designed for use with arduino. I have tried it use with Raspberry Pi and STM32 (on STM32F429 discovery board). Sensor is in ...
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1answer
94 views

Debugging I2C, Effect of Oscilloscope Probes

Working on a simple I2C setup: Raspberry Pi connected to a WM8731 audio chip. The Raspberry Pi configures the WM8731 (which is write only) over I2C. Problem is WM8731 doesn't always respond with ...
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3answers
78 views

Can I use a Dupont cable with a resistor soldered in the middle as a pullup resistor for I2C comms?

The short question: is there a difference between using (on a breadboard) a standard through-hole 10K pullup resistor, versus using a modded Dupont cable with a 10K pullup resistor soldered in the ...
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60 views

STML052K8U + DS3232: I2C not working

I have a problem, I use a microcontroller and RTC STM32L052K8U DS3232M and I can not connect via I2C with RTC, using the HAL library. From the watch constantly comes NACK. The wizard sends the correct ...
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2answers
44 views

How are bits put on a bus, the i2c for example?

I have been to school and through these topics, understand that "bits on a bus" is a behaviour emerging from the very way a CPU works. But still, I suppose this requires some interaction... it doesn't ...
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29 views

How to model I2C in SIMetrix?

I need to create a model for I2C for the interface with other blocks in SIMetrix or SIMPLIS, any ideas?
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1answer
29 views

Does the Si4731 / Si47xx provide the necessary info to fetch left/right demodulated audio levels?

I'm working on a project which uses an Si4731 broadcast radio receiver IC (Si47xx family) and which calls for left & right demodulated audio level meters based on a source FM broadcast signal. I ...
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1answer
96 views

I2C design with secure message

Is it possible to secure I2C communication between slave and master so nobody else can connect their devices to the master. Basically encrypting the message. Is this feasible by software or hardware?...
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1answer
67 views

How can I enable a LDO using the I2C SCL signal

Can I enable/disable an LDO (more specifically NCV8163AMX280TBG) by using the I2C SCL signal? This would allow me to turn ON the regulator once a master starts the I2C protocol and turn it off once ...
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1answer
58 views

No signal output on I2C bus

I have an ESP-WROOM-32 (I2C master) and an ATmega328p (I2C slave, address 0x03) assembled on a prototype PCB using external 6k8 pull-ups. I'm using the ESP's default I2C pins 21 (SDA) and 22 (SCL) as ...
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24 views

What does the values of 0x10 and 0x08 mean for gyroscope MPU6050 registers?

I am trying to connect a gyroscope MPU6050 to arduino ATmega2560 and read its raw values from its 6DOF (gyro and acc). I found the following code: ...
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111 views

The use of redundant I2C in spacecraft avionics

I recently read this report about the JPL x2000 avionics development project, which developed more modular avionics platform using commercial silicon, to cut cost and power. They opted for an ...
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2answers
69 views

Choosing correct DAC: DNL and INL

let me know what I state below is correct or not. Regarding the DNL and INL of a DAC, DNL is the error difference between actual step width and ideal value (1 LSB). INL is the deviation of actual ...
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1answer
168 views

I2C bus occupied

I have a problem with an I2C communication and want you to ask whether there is a better solution than mine. I am programming an STM32F103 at the moment. There is one sensor (MPU6050) which is ...
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1answer
340 views

I2C IC for part identification

I am looking for a way for a host system to identify that a certain mechanical module C is connected to it. This mechanical module doesn't need to have any electronics in it, but due to host ...
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27 views

PMBus multi-slave issue

I have PMBus slave device: A, B, C all running at 400kHz. There is a dongle which connects to a laptop as PMBus master. There is also GUI to display. Board A, B, C have slave address (7-bit) 0x50, ...
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1answer
58 views

I2C & SPI - share clock lines?

I know mixing SPI and I2C is a bad idea, but, when using a microcontroller short on pins, is it safe to share clocks between both buses, provided both are running at bus-tolerable frequencies? In my ...
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1answer
154 views

Why do many uC have more then one I2C interfaces? [duplicate]

On I2C buses you can hock up 112 devices. So why do so many microcontrollers have up to four I2C ports, when you could just operate enough devices for most applications on one I2C interface?
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37 views

reading a bit from VCNL4010 sensor through I²C

I'm using the MSP430FR2433 LaunchPad. I'm trying to interface with a VCNL4010 sensor to my MSP device via I²C. After entering into Transmit(); I'm ...
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1answer
24 views

QT1070 inconsistent readings on touch pins

I recently transitioned my projects capacitive touch IC from using the MPR121 to the QT1070. I am getting irregular/inconsistent readings on one of the touch pins. In this particular situation, it ...
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1answer
49 views

stm32f401 I2C does not send byte after repeated start

I am programming an I2C master on a STM32F401 nucleo board. I program it without HAL, just using registers. I am interfacing a peripheral, that has to be read like the following: Start Write ...
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3answers
156 views

I2C slave not ACK'ing quickly enough

I am programming a microcontroller to talk with a slave device via I2C. My I2C transactions always get NACK'd, but I believe the slave is ACK'ing the transaction, just a little bit too late and my ...
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5answers
139 views

I2C monitoring without Microcontroller [closed]

I am trying to read data from an I2C connected touch sensor. Specifically the Azotec IQS266. I plan to preprogram all of the settings the way I want them, and then not touch them again after that. In ...
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3answers
57 views

Synchronizing two OV7670 image sensors

I would like to create a simple frame synchronihed stereo camera. I found there are cheap OV7670 boards (without FIFO memory) that work with Arduino (or compatible) boards - these sensors do not have ...
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1answer
96 views

STM32 I2C Read Variable Length message from Slave

I have two devices that must communicate over I2C. The master writes some data to the slave, and then it must read back a response from the slave. Neither the slave nor the master knows the length ...
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33 views

Can I program an ATtiny85 using AVR SPI headers with I2C peripherals attached

I am preparing a schematic that includes an ATtiny85 MCU and a few I2C peripherals. It also has a MOSFET attached to pin 6 that drives a motor. I plan to use an AVR header to program my device. I'm ...
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1answer
50 views

I2C write to Amis 30624 motor from Atsame54p20a in Atmel Studio

I have been trying to write to the amis 30624 stepper motor (http://www.onsemi.com/pub/Collateral/AMIS-30624-D.PDF) using I2C protocol but for some reason its giving me Receive ...
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1answer
82 views

evaluating ESD protection for 3.3V i2c

Even though there are questions about ESD protection for i2c bus already in this forum, I wanted to ask how to suppress the clamping voltage of a TVS diode to a safe level. As an example, the ...
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2answers
97 views

Switch a differential I²C bus section, controlled via I²C

I want to separate a section of an I²C bus, controlled via an I²C message. (Similar to an I²C bus switch/multiplexer like e.g. PCA9540.) Indeed the I²C bus to switch isn't a plain vanilla I²C bus, ...
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1answer
48 views

Pull up/down a pin on a PCA9536 does not register?

Quite a obscure question here, concerning a very specific I2C expander IC, however I believe that this example can be replicated with most expander bus ICs. I am using a PCA9536 to switch the 4 pins ...
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3answers
79 views

How can I see an output from SCL?

I am new to electronics, circuits, etc. Currently I am reading I2C and synchronous serial communications. As I understand, two devices must be connected to the same CLOCK wire so that the slave knows ...
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1answer
52 views

Accessing I2C address of ADT7516 ( Temp sensor )

I have a BeagleBone Green and an EVAL board of ADT7516. I connected them by SDA and SCL pins and as they are to be connected with the PC by the usb port, they will have a common ground. After this ...
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1answer
103 views

Can I use I2C protocol for product with SPI interface ICs?

I am working on FPGA project where I have to configure the onboard ICs with SPI interface specified in their datasheets and few with the I2C interface. I was wondering that, is it possible to bring ...
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2answers
886 views

Why does putting resistors between Vcc/SDA & Vcc/SCL in I2C result in a square wave?

I'm trying to understand why placing resistors between Vcc and the data/clock lines helps my waveform be square, when I'm communicating between Arduino and an EEPROM chip. If resistors are not placed ...
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1answer
60 views

Esp32 i2c read command produces no clock signal

I am trying to read temperature from a SHT21 sensor using an ESP32-WROOM board. The I2C driver is from ESP-IDF SDK. This is my reading sequence: ...
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3answers
116 views

Multiple I²C slaves with different addresses VS. using a multiplexer

I'd like to interface a lot of identical I²C sensors, let's say 32, with a MCU that has only 2 I²C busses. I can configure each sensor to have up to 8 different addresses. Hence I can have 8 sensors ...
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2answers
129 views

ATMEL 24C02 EEPROM - Trouble understanding how the addressing works

I am currently writing a library for ATMEL's 24C series EEPROMs (not a programming question). The library works fine with a single EEPROM at the moment and I am trying to support multiple EEPROMs now, ...
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4answers
218 views

Raspberry Pi Zero connection to sensor (with I²C or SPI bus interface) over a large distance

SUMMARY: Here is what works: Raspberry Pi (I²C) <-> 1 m cable <-> sensor (I²C) Here is what I'm trying to do (doesn't work, hence question): Raspberry Pi (I²C) <-> 30 m cable <-> ...
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3answers
191 views

Can SPI and I2C be implemented using GPIO pins?

Can SPI and I2C be implemented using digital GPIO pins? I.e. can the SDA and SCK pins of I2C and the ...
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1answer
67 views

I2C / TWI freezing with SDA stuck at LOW

In my project I have connected multiple sensor breakout boards to an Arduino-Pro-Mini running at 3.3V and 8Mhz as follows on a fabricated pcb This is how the proto-pcb looks: You will see that all ...
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0answers
41 views

STMF4xx MPU6050

I have problem with reading data from MPU6050 to STM32F4 nucleo board. The connection is with I2C. The problem is that in the first function IsDeviceReady the device is recognised and the LED does ...
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0answers
40 views

I2C on STM32L100 - “faulted start”

I'm using stm32l100C6-A to communicate with gas gauge via I2C. My code tries to start I2C transfer, like this: ...
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2answers
62 views

Parallel EEPROM write to with I2C

I was wondering if there is a hybrid between the serial and parallel EEPROM's? What I mean is, is there an EEPROM that can be written to over I2C and then once it is setup can be controlled with some ...
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2answers
141 views

STM32f030C8 I2C EEPROM -no data received when read after a write

I am developing library for I2C eeprom at24c04 with stm32f030c8. My read and write functions work but when i try to read immediately after a write to eeprom, the eeprom doest return any data. however ...
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77 views

SCL and GND connection [closed]

What happens if SCL of I2C is connected to GND? Does it ruin our controllers clock as well? I am using PIC24 with three I2Cs. If one I2C's GND and SCL gets short circuited. I stop getting the data of ...
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4answers
119 views

how long should an I2C slave wait for a STOP bit (if at all)?

I2C frames each group of message bytes in START and STOP conditions, defined as SDA changing state 1>0 or 0>1 (respectively) while SCL is high, as described here. I am writing interrupt driven ...
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1answer
23 views

DRV8830 motor controller — drive is working but brake is not

DRV8830 datasheet (control register info around page 11). I have gotten this chip to run a motor with the following code: ...
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3answers
63 views

Problems understanding I2C pullup calculation

I have been trying to read about I2C pullups such that I can select an appropriate pullup resistor for an EEPROM (24LC02B-I/P) which I want to use as serial ROM to drive some 7-segment displays. ...
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2answers
139 views

ESP8266 I2C Multiplexer

EDIT: I ran an i2c bus scanning program and it detected a device at 0x70 (the mux). I connected the device I am trying to interface with directly to the i2c bus and ran this code and it worked ...