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.

Filter by
Sorted by
Tagged with
0
votes
1answer
47 views

I2C setting MCU as both slave and master at the same time

Hello everyone I'm working on a new project with the TI MSP432P401R microcontroller. I want to have 2 separate I2C buses. I2C bus 1 will set the MCU as the master, whereas the DAC and the pressure ...
0
votes
2answers
32 views

MSP430 MPU9250 MPU6050 I2C: After sending the address NACK

I have a problem with read from my MPU6050/MPU9250. Both are connected with AD0 to ground so both should have the address 0x68. With both sensors the same behaviour ...
0
votes
0answers
45 views

Gathering accelerometer data over I2C not updating every 1 ms

I am using an STM microchip to communicate with an IMU over I2C. I am requesting 3 axis of acceleration information from the IMU (x,y,z). I have the ODR Selection frequency set at 1.66 kHz. Currently ...
1
vote
3answers
42 views

What is the difference between a multiplexed bus and a multi-master bus

The jargon of terms in bus architecture literature is half the difficulty in understanding it. At some places the term 'multiplexed' bus is used while at some other places 'multi-master' bus is used. ...
0
votes
1answer
41 views

I2C max pull-up resistors and current sink

I design a system with several devices connected to 400kHz I2C interface with wires. For now, I get shark fins instead of square waves, so I decrease pull up resistors value. The MCU, which drives ...
0
votes
1answer
34 views

PCF8563 RTC false reading

This my first time to deal with RTC. I forget to add the crystal oscillator to the OSCI of the PCF8563 chip (I thought it has an internal oscillator). Therefore, I had to insert a 32.768kHz (sine wave)...
0
votes
2answers
94 views

RS-232 to I2C communication [on hold]

I'm trying to establish communication between two boards, one of which has an RS232 output and the other with an I2C input. I've looked for adapters online and the only ones I've found seem to be ...
3
votes
3answers
71 views

Most significant Bit first Vs Least significant bit first

I am studying protocols and came across a concept of MS bit first(in I2C) and LS bit first(in UART). I couldnot understand the advantage/limitations one has over the other? on what basis is it ...
-1
votes
0answers
26 views

libopencm3 bus communication (spi/i²c) fails with more complex programs

I'm using libopencm3 on a STM32F103C8 and have a (to me) strange behavior. I successfully used the spi (spi_xfer) and i²c (i2c_transfer7) subsystem (independent from each other). But as soon as the ...
0
votes
0answers
60 views

Why HAL_I2C_Master_Transmit always returns HAL_BUSY?

I'm trying to use I2C between an STM32F103C8T6 development board and an Arduino Uno. However, I always get a HAL_BUSY error when I call HAL_I2C_Master_Transmit in ...
0
votes
1answer
40 views

I2C in STM32F103 longer data

I am trying to use PCA9539 as an IOexpander for my project. I have a STM32F103 connected to PCA9539 via I2C. The problem I have is to write into PCA9539. Based on the datasheet I should to send (1) ...
0
votes
1answer
43 views

Suggestions on wiring PCA9685 i2c + TB67H303 motor ic

I'm trying to design a circuit in order to use the TB67H303 motor driver with the ATMEGA328p and the i2c protocol by using the PCA9685 controller. I never used the TB67H303 and the PCA9685 chips ...
1
vote
1answer
46 views

Lighting up LEDS via I2C Bus of a NeoTrellis 4x4 RGB Led Matrix

Many attempts to write to an i2c slave to make rgb leds light up have failed. The hardware in question is found at: https://learn.adafruit.com/adafruit-neotrellis There is an arduino library and a ...
0
votes
0answers
62 views

Embedded system with hot swapable sub modules

I am designing a embedded system where a master microcontroller (or possibly a SoC) needs to communicate with several different sub modules with a microcontroller of their own. The sub modules should ...
0
votes
2answers
66 views

Using higher I2C voltage then MCU supply (but still in limits)

I am working on a project where there is 1x MCU and 2x I2C devices device needs 2.8 V using I2C1 device needs 3.3 V using I2C2 (I have a need of seperating bus apart) If I understand correctly, a ...
0
votes
0answers
50 views

PCB Ground Plane on Two Layer High Signal Density Board

To give an overview of the design. I am creating a PCB with a header connection for raspberry pi that will use RPI I2C capabilities and GPIO to control board mounted integrated circuits whose outputs ...
1
vote
0answers
26 views

mcp2221 i2c CLOCK down after ACK

I am trying to control an Analog Devices programming resistor AD5254 by a USB to I2C master device from MicroChip MCP2221. The problem I am facing is that each time MCP2221 is waiting for ACK from ...
1
vote
1answer
30 views

ATmega2560 I2C (TWI) assembler configuration problems

I am using ATmega2560 for testing an I2C code. I wrote subrutines in assembler for init, start, write, read and stop the I2C setup. The goal is that master writes 11110000 to a slave with address ...
6
votes
3answers
887 views

VHDL: What is correct way to model open collector output for FPGA?

I2C uses open collector outputs. FPGAs do not have such outputs. They do have tri state buffers though. How should open collector output be defined in a VHDL for an FPGA? How should open collector ...
-5
votes
2answers
39 views

How does line encoding relate to bus protocols like SPI, serial, i2C, ethernet etc [closed]

I'm referring to line codes like bipolar, machester, miller etc... https://en.m.wikipedia.org/wiki/Line_code How do these line codes relate to bus protocols? Is it another level down? Is it ...
1
vote
1answer
47 views

Raspberry Pi I2C with multiple slaves behaves erratically

I have a Raspberry Pi 3B+ that I'm using with two I2C devices on the same bus. The first device is a DAC from Adafruit (product here). The second device is an accelerometer, also from Adafruit (...
0
votes
0answers
47 views

High speed multiplexing for multiple I2C devices [duplicate]

I'm trying to connect 32 I²C "root of trust" NXP A71CH devices. https://www.nxp.com/products/identification-security/authentication/plug-and-trust-the-fast-easy-way-to-deploy-secure-iot-connections:...
0
votes
2answers
65 views

Writing to registers on I2C device

I'm currently working on a side project which uses an SSD1306 128x64 OLED display. I'm then using I2C to communicate to this. However, I'd like to better understand what exactly is going on when I'm ...
0
votes
1answer
42 views

Can an I2C switch control multiple I2C switches?

I was wondering if I am able to treat an I2C switch simply as another I2C device and use 1 switch to control more switches downstream. This picture below shows what I am trying to do.
1
vote
1answer
40 views

Why are input and output of I2C voltage level shifters connected?

Below is a schematic for a board from ST for testing VL53L1X sensor. It converts 3.3V to 2.8V internally because the sensor's recommended operating voltage is 2.8V. The green lines are SCL and SDA ...
0
votes
0answers
63 views

PX4FLOW (Optical Flow sensor) - Powering with 5v. Does it work with OmniNXTF7 I2C SCL/SDA at 3.3v?

I want to use PX4FLOW with OmniNXTF7 flight controller. This flight controller has 3.3v I2C SCL/SDA and no PullUp-resistors. I use the PX4FLOW only with I2C port, with 5v at VCC (not 3.3v). Does ...
0
votes
1answer
78 views

Connecting up to 32 Devices I2C

I'm trying to connect 32 I²C "root of trust" NXP A71CH devices. I'm thinking about a good way that does that, I mean what kind of communication should I use? A digital multiplexer that selects a ...
0
votes
0answers
50 views

Altium: Repeating SPI/I2C Blocks

What is the proper way of repeating I2C/SPI blocks? Since we know in the case of SPI blocks, MISO, MOSI & SCK must all be tied together in a single bus for communication to happen. I have read ...
0
votes
1answer
30 views

Is DS28EC20 (20Kb 1-Wire EEPROM) a secondary address of I2C?

I have a MCU (nucleo64 L476RG), connected with I2C, and I2C is connected with DS2482-100 (Single-Channel 1-Wire Master), then to a DS28EC20 (20Kb 1-Wire EEPROM). I create project from stm32cubeMX and ...
3
votes
0answers
136 views

Strange I2C communication

I am currently trying to test the SHT3x series humidity sensors by Senserion. I have their EK-H4 evaluation kit to get data from the sensors. I can plug in the sesnsors provided with the kit, and all ...
0
votes
2answers
90 views

How to find I2C address of DS2482-100?

I am using stm32cubemx to create an I2C project. I am using nucleo64 L476RG to connect with I2C ds2482-100, and another 1-wire DS28EC20 is connected with I2C. I am very new to this project. The first ...
0
votes
2answers
103 views

Extremely low data rate transmission over long distance for attinys

For a lighting project I need to be able to trigger 20 units every couple of seconds independently which are daisy chained with 1-2 m space between each of them like so: Control station ====== Unit 1 ...
0
votes
2answers
102 views

I2C Communication Between STM32F3 and SSD1306

I am trying to write data to my 128x32 OLED display. I researched it online and found that it has the SSD1306 controller connected to the display. It uses the I2C protocol and it only has 4 pins (VCC, ...
1
vote
0answers
50 views

How to properly implement I2C communication between two or more STM32s?

I have a master board with STM32F030R8 and two daughter boards with STM32F030C6. The objective is to communicate parameters between the boards periodically and also on-demand. With some effort I ...
0
votes
0answers
43 views

Long-Distance Multi-Slave Communication

I am currently trying to connect many serial slave devices to my Arduino device over a 14 meter distance. I am looking to have slave-to-master communication. These devices include: 3 BME280 ...
0
votes
2answers
90 views

What is the triangle components in this diagram?

I am reading through datasheet of a voltage translator for I2C (FXMA2102) and I cannot understand the triangle components in the block diagram: Are they diodes to make current flow in one direction? ...
0
votes
1answer
76 views

Detect an unknown communication protocol and read data on it

We have old type textile machinery in our factory. (open end machine) on the machine's screen is showing the operating efficiency of the machine. Under the hood, When I follow the cables, the sensors ...
0
votes
1answer
76 views

Distance between UART and I2C bus

I create a board with two bus: UART and I2C. Now I am expanding the connection terminal, which has the following contacts: RX / TX / SDA / SCL / + 5V / GND. The question is, do the I2C and UART buses ...
2
votes
0answers
51 views

Address Sent bit is not set on STM32F4 Disco

I am trying to interface my STM32F4 Discovery board with a sensor that works over i2c, since the sensor required a specialized i2c protocol, I decided to implement my functions using registers. But ...
1
vote
1answer
59 views
1
vote
3answers
87 views

How to generate NACK on STM32F407

Is there a way to send a NACK on I2C on STM32F407? There is no way to do that using the HAL, and the datasheet says nothing about it.
0
votes
1answer
40 views

FMPI2C on STM32F407

Is it possible to use Fast mode I2C on STM32F407 ? I looked everywhere for the I2CX pins GPIO but Can't find them at all.
0
votes
0answers
56 views

Interfacing A71CH with I2C

I'm trying to interface the following chip with STM32F4 https://www.nxp.com/docs/en/supporting-information/AN12207.pdf I'm currently trying to transmit a repeated start using hal sequential ...
0
votes
1answer
54 views

Checking my mpu6050 schematic

I am fairly new to pcb design and I just created a mpu6050 chip that will work with an Arduino microprocessor. I want to make sure the hookup is all correct before I start work on the other parts, as ...
1
vote
0answers
83 views

I2C get stuck on busy with DMA interrupt

I'm trying to interface with NXP device using I2C. I'm initializing it that way ...
0
votes
1answer
51 views

I2C master and slave use different power sources

I have two slaves on the I2C bus. Before, both master and slaves used the same power source (2.8V), and the I2C bus works fine. Today, I changed the master to another power source (3.3V), keep the ...
1
vote
1answer
25 views

TCA6408ARGTR input inversion trouble

I'm curious, Has anyone used this http://www.ti.com/lit/ds/symlink/tca6408a.pdf part? I just tracked back a sign error to the read values remaining active low after I set the inversion register on ...
1
vote
1answer
115 views

PIC I2C communication problem with I2C multiplexer

I need to read data from 3 of the same kind of batteries with SMBus so I decided to use an I2C multiplexer for this purpose. I can communicate with 1 battery without any error. But I cannot ...
5
votes
5answers
1k views

Can only the master initiate communication in SPI whereas in I2C the slave can also initiate the communication?

Is it possible for a slave to initiate communication in SPI? I thought due to the chip select i.e. NSS feature only master can communicate the communication. However, in I2C, the slave can also ...
0
votes
2answers
87 views

How to verify a VHDL I2C master?

Once an I2C master has been written, the next step is verification. Provided that a BFM for the slave does not exist, how should one go about doing this? Also seeing how I2C is open collector in ...