Questions tagged [smbus]

System Management Bus (SMBus or SMB for short) is a single-ended two-wire bus derived from I2C.

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Detect power/run status of PC in hardware

This may well be a daft question and/or a failure to google effectively (and apologies if this would be a better fit on SuperUser or somewhere else?) but is it possible, in low-level hardware, to ...
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Slow read from IST8308 via I2C using Python and smbus2

I have an Arm64 Linux board and an IST8308 3D magnetometer that I am reading via I2C with the following script: ...
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Multiple PCIe devices in a single M.2 slot

I have a M.2 M-keyed slot on my laptop, and multiple M.2 PCI-e devices that I'd like to use at the same time. I've been looking for a M.2 switch or splitter of sorts but couldn't find anything, so I ...
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SMBus ARP working example

I've been playing around with an arduino and a few sensors when I came across this amazing communication protocol I2C with which a master can communicate with all of the sensors (or slaves in a more ...
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SMBUS on STM32F091

Any example code available to implement smbus(master and slave) interrupt mode on stm32f091rc ? Tried using the HAL functions was not successful? In Master mode to transmit I use while(1) { while(...
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Writing to BQ25700A with i2c_smbus_write_block_data

I'm trying to write to a TI buck boost charger (BQ25700A) using the i2c_smbus_write_block_data command, to try to provide current to a battery. ...
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No voltage at battery terminals

I replaced the cells on my Laptop unfortunately disconnected BMS while doing so. HP battery check says each cell voltage and Temp correctly and calibration warning but can't calibrate as no terminal ...
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How to calculate the Samples per second possible of a ADC (MAXIM 11605) using i2c with raspberry pi?

I would like to find out how many samples per second this ADC im using is capable of with a raspberry pi using i2c and python SMBUS2 library, but i dont know where to start. As far as i know this ...
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Why are VOL and IOL seperately defined in I2C and SMBUS?

What is the point of defining VOL and IOL separately in I2C and SMBUS?
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What kind of application forces SMBus to specify a "TIMEOUT" that keeps the minimum frequency to 10Khz?

Why "TIMEOUT" has been defined in SMBus that forces the minimum frequency to be 10kHz? Please tell a solid industrial application.
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What is the maximum capacitance allowed on SMBus? Why was the VIL fixed to a maximum of 0.8V?

How to interpret the significance of DC specification in SMBus? Why is the VIH value has been fixed to a minimum of 2.1V?
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STM32 trying to communicate with 2 I2C. But second one fails

I am trying to communicate with a battery using SMBUS. Battery has 2 sections so it uses 2 separate SMBUS lines. I am trying to read SOC information from two section by using STM32F103C8. First ...
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STM32 I2C transmitting no data and cannot change the data that is being transmitted

I am trying to establish a SMBus connection by using STM32 chip. When I try to transmit data to battery (0x0D) I see 0x0B with oscilloscope. When I change the data that is being transmitted to 0x00 or ...
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how to understand SMBus SDA line captured waveform

I am using MCU (L476RG) with PMM240 (power management board) and RRC 2054-2(battery), I am figuring out why SMBus is always busy after sending command to slave, so I captured the waveform when I send ...
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Why does each device have two SMBus addresses?

I am working on PMM240 (a power management board for RRC battery) with RRC2054-2 battery. First when I only connect PMM240, the manual has address 0x20, but when I scan the port, I have two addresses,...
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SMBus is always busy after HAL_SMBUS_Master_Transmit_IT()

I'm using PMM240 power management board to control battery RRC-2054, and I have problem to use SMBus, please see the code I listed below, looks device is ready, but when you send something, it is ...
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Disadvantage of using low resistor value for pull up (Strong pull up)

I was trying to choose a resistor value for a pull-up resistor I will use in my project. The project will have I2C communication and SMBus communication. When I was searching on the internet, I have ...
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SMBus pull-up resistor value

Hello I need to communicate with a device using SMBus. However, I could not choose correct value for pull up resistors. Vdd is 4.9V and I use SMBus. In same conditions for I2C communications I used 2k ...
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SMBus Read Word Protocol

I want to communicate with a device that is using SMBus. I use PIC18F26K83. I am inexperienced but before that I implemented I2C communication. In I2C communication, what I do in order to write to ...
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PIC I2C Clock selection

Hello I will be communicating with a device using SMBus. For this, I will be using PIC18F26K83. Timing is not important for me so I m somehow free to choose any clock frequency for my MCU. Well higher,...
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1 answer
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IC has pull-down resistors on SMBus lines?

The datasheet of TI bq40z50-R2 (Li-Ion Battery Pack Manager) tells that "The SMBus clock and data lines have internal pulldown". Pin equivalent Diagram is in image below: Aren't usually the SMBus ...
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PIC I2C PPS mapping

I will be communicating with some device via SMBus. I use PIC18F26K83 and I will use RB1 and RB2 pins as SCL and SDA pins. My question is about PPS mapping. In datasheet it says that I need to set ...
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SMBus: Is 100 kHz clock a risky frequency?

I will communicate with a device via SMBus. I use PIC18F26K83 for this. In SMBus spec it says clock minimum clock frequency is 10 kHz and maximum clock frequency is 100 kHz. Would it be a risk to use ...
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SMBus v1.1 voltage threshhold value

I am planning to use PIC18F26K83 and communicate with a smart battery that uses SMBus ver 1.1. So from the datasheet of PIC it says I need to choose appropriate input threshhold for SMBus from RxyI2C ...
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SMBus Address and BaudRate

Hello I need to communicate with some batteries ( BT-70791CK from BrenTronics). They use SMBus ver 1.1 for communication, but in datasheet of the batteries there is no information about the SMBus ...
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SMBus default Baudrate and Address

I am trying to communicate with some batteries that uses SMBus. In the documens of batteries it only specifies the SMBus version which is SMBus v1.1 and do not mention about addresses nor the baudrate ...
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What does it mean when i2c_smbus_read_byte() returns 0

i2c_smbus_read_byte() returns a negative value when there is an error in reading data. But what if it returns 0? Following is the code from adt7316-i2c driver ...
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How should I used two MLX90614 sensor on one Arudino Uno given that the sensor has a fixed I2C bus adress? [duplicate]

I have an arduino uno and want to use a non MLX90614. I plan to used more than one sensor on the same Arduino but I don't know how to use two MLX90614 on the same I2C bus.
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4 answers
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STM32F103C8T6 - I2C communication with TI FuelGauge BQ78350

I am trying to establish communication between TI BQ78350 FuelGauge and STM32F103C8T6 using I2C/SMBus. The following is the I2C configuration used for the standard HAL I2C library. ...
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How does integrated displays controlled by the computer?

Consider a run off the mill pc: lcd displays connected, you have brightness control in the menu of the lcd. And some other stuff like color temp and modes. Now consider a laptop, AIOs and kiosk PCs. ...
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LTC4015 variable i2c speed operation

I am planning to use LTC4015 IC for buck charger application . I have to interface the IC with my host MCU. LTC4015 PRODUCT PAGE I have other charge controlller ICs connected over same I2C bus. ...
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What are the various ways in which an I2C bus may hang

I am very new to electronics and have entered in the territory of I2C bus. Want to understand the behaviour of compliant devices as per I2C protocol specification. One condition as per the link below ...
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Bus isolation circuit

I got a question about BUS isolation circuits. Is this a correct design? Looks not to me. The book said that if POWOK is high, two SMBUS will connect together. But I think it's wrong, the NMOS should ...
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Is this chip 0.5mm pin pitch?

Am I correct in thinking that this chip has 0.5mm pin pitch? I don't know where to look for it on the details of the chip! When I google for '144-LQFP' I found a link which suggests it is 0.5mm pitch ...
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Compatibility between I2C and SMBus

I am looking to interface a Melexis IR sensor to a AVR micro(ATmega2560). The sensor has an SMBus interface. The datasheet of the micro does not explicitly state that it supports SMBus. But it has a ...
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How to set NACK on bad PEC in TWI used for SMBUS (ATMega8) [duplicate]

I want to implement the SMBUS protocol in my AVR device (ATMega1284P), which will have the role of slave. I need to support the PEC (Packet Error Code) feature, which means that the master device (...
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2 votes
2 answers
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Possibility of SMBus/PMBus device with I2C Master?

Can I communicate with a SMBus/PMBus device with I2C? I've been reading the specs and getting quite confused. It seems to me the only difference is the voltage levels and the need to have a restart ...
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Problem I2C NACK in 3rd byte MLX90614 - Repeated Start

I am trying to read Melexis MLX90614 infrared temperature sensor through SMBus (I2C or TWK like protocol). The protocol (SMBus) implement an special type of command or sequence called repeated start, ...
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7 votes
2 answers
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Is there a standard I2C/SM bus protocol for laptop battery packs

I'm building a laptop with a custom battery pack. I know that the pack has to communicate through an I2C/SM port on the motherboard, but I don't know how to make the bios/os recognize it. Is there a ...
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I2C slave compatible with SMBus protocol?

I do have some inquiries regarding using an I2C slave controller (from Arria 10 FPGA). We are currently assessing MCTP protocol support in our device, whose physical layer is built upon SMBus/I2C, ...
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What is the host in this schematic?

In this schematic it shows the smbus as a separate unit, what im wanting to know is this a seperate ic that i have to integrate in or is it just simple as a usb port? (source: www.ti.com)
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MLX90616 Infra Red Temperature Sensor problem

Recently I have been trying to interface with the MLX90616 an infra red temperature sensor by Melexis. After reading the datasheet I have I have written a program to take the object temperature ...
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1 vote
2 answers
105 views

Using on chip I2C on NXP P89LPC954

I am trying to use on chip I2C on NXP P89LPC954 microcontroller(80C51 based) for voltage monitoring. I have two voltage monitoring chips of same kind(same chip with same register address) connected ...
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Does SMBus spec lie about I2C?

In the SMBus spec it says: The I²C specifications do not require that a device always acknowledge its own address. This can confuse a system controller. If a device does not acknowledge its own ...
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PS2 / SMBus communication

I have an OEM touchpad I want to connect to a PC. The drivers for this touchpad are widely available. I asked the manufacturer for the original datasheet, and it says there, that the touchpad ...
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SMBus using Silicon Labs C8051F560

I am trying to communicate an arduino with a Silabs F560 Toolstick Daughter Card. On Arduino (Master) I have loaded the i2c scanner program from http://playground.arduino.cc/Main/I2cScanner which ...
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How does SMBus receive byte command protocol know what to send?

Im programming an I2C device to act as a PMBus slave. Looking at the SMBus protocols (which PMBus is built on) the Receive Byte command has a format described as follows: ...
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My CRC8 is dysfunctional and I'm not sure why!

So I'm interfacing an arduino with a Melexis temperature sensor, and it's going okay--aside from the fact that I can't seem to get the CRC check to work. I've gotten read operations to complete ...
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Is it possible to only utilise SMBus on PCI Express 1X?

According to the Wikipedia page on PCI Express, the PCI-e 1X slots have 18 pin positions on two lanes (so 36 pins) and positions 5-9 represent SMBus and JTAG. I'd like to hook up a µC as an ...
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Raspberry Pi with SMBus SmartBattery

I'm trying to interface a Raspberry Pi with the mini-box OpenUPS. It claims to implement the Smart Battery SMBus specifications. I can read data from the device using the i2c_smbus_read_word_data() ...
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