Questions tagged [slave]

A slave is the device being controlled on a bus. Specify and tag with the specific protocol used.

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Topology and protocol for boards connection

Would like to have some insight on which data protocol to use to communicate between a master and several slave boards on a project i'm working on. My initial idea was to daisy chain all the slaves. ...
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RS-485 Network Topology with Backbone and Daisy-Chain Stubs [closed]

I am designing a RS-485 network and would like to know whether the configuration below would work. The transceiver I am using is the Maxim MAX485, with the master ad slaves hardwired to always ...
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RS-485 communication with slave microcontrollers driving addressable LEDs?

I am trying to figure out how to achieve the master-slave configuration shown below. The aim is to individually address an array of 150mA LEDs, driven by the IS31FL3265A PWM driver. For this specific ...
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PL-PS communicatioin software in SDK

I need your help in understanding a task. I work on this task the second week and didn't get any results. I work on a design PL-PS communication. I use the Zynq board to test my software. In the ...
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(beginner) I2C target protocol: basic in bit transmission [closed]

I am studying I2C protocol and have some questions: I2C and SPI are communication protocols. They work the same but I2C does not have chip select like SPI. I2C has ...
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Set up STM32f1xx MCU for SPI communication in slave mode

I set up an stm32f1xx MCU SPI for slave mode. How can I write in the SPI shift register that whenever the controller starts a full-duplex communication, the data written to the SPI shift register is ...
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How to detect an I2C slave presence/ absence as an interrupt?

Involved in a task to build a test equipment with a ARM M4F microcontroller for the purpose of testing various PCBs. One of the PCBs has I2C compatible current/voltage monitoring chip on it. Is there ...
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RS485 burnt slaves after short-circuit

I have a question regarding a scenario I found myself in, hoping that someone can clarify if the scenario I'm going to illustrate is possible (short premise: I'm a programmer, I'm not an electrician ...
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Data boundries in SPI serial interface

I am trying to understand the SPI serial interface between a Master MCU and a (Single) Slave ADC. Do we have 8-bits or 16-bits data word communication in SPI? Or is it un-bounded and I can send any ...
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SPI Slave implementation in software

I need to implement SPI Slave (@10Mhz clock) on a microcontroller (a sensor with Cortex M33 core) in software. The problem is software is not fast enough to prepare data just after the command. (also ...
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How to setup STM32 as I2C target device?

I've been trying to set up MCU (STM32 L432KC) as an I2C target device. I have previously tested it as a controller device to interface with a port expander (MCP2307) and it works perfectly fine. The ...
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Use half-duplex or full-duplex RS-485?

I have a master microcontroller that can control 4 slave microcontrollers. Each slave microcontroller is connected to 3 sensors. The master microcontroller asks to retrieve the value of a specific ...
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MCU based I2C master receiver mode includes transmitter mode or not?

If I am programming an MCU I2C peripheral as a master of I2C bus that will be receiving data from other slaves on the bus. So I will set its direction as 'I2C_Receiver.' But since an I2C slave will ...
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MCU to MCU I2C communication

I have 2 MCUs and I want to connect them together over I2C bus. MCU1 will be Master while MCU2 will be Slave. Only these 2 MCUs are on the bus. This configuration is fixed and I cannot change it. ...
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7 votes
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Way to determine order of cards plugged into controller board

REVISED: I have a master controller PCB with four bus bars (+, -, and two signal lines), see image below. I have module PCBs A-C (or could be 10 or 15 of them), each with MCUs and unique identifiers, ...
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Modbus slave firmware development

I'm developing a simple RS485 based MODBUS slave application on a Microchip PIC micro-controller and need to know best practices to follow on its application side. I can guide myself to get the ...
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2 answers
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How to connect multiple devices to UART bus? [closed]

I want to use a UART bus (RX-TX-GND) to communicate between one master and multiple slaves. NUCLEO-F401RE board is the bus master. B-L072Z-LRWAN1 and ESP32 are the slaves. Communication over UART ...
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Assembler program showing ACK even with the wrong slave address, I2C code problem!

I have this project communicating MPR121 capacitive touch sensing keyboard with 8051 microcontroller, with some references I've implemented some I2C code for serial communication between master and ...
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Check if the slave is receiving data from microcontroller and transmitting back successfully, I2C?

I have this project where I have to communicate MPR121 touch sensor keyboard with 8051 microcontroller via I2C, I've implemented the code and when I execute it I don't really know whether slave is ...
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286 views

I2C Put One Termination Res at the End or on Each Slave Board

I Have a system with I2C bus wired just like this: My questions is which one is better: put the termination pull up res at the end of connection (on the last board), or put pull up res on each slave ...
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Single controller I2C with multiple target devices

I have a one I2C controller with 14 I2C target devices connected on the bus. I want to clarify the order of things that happen on the I2C bus. Let say the controller sends an ADDRESS. All the target ...
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Multiple slaves with identical address on multi-master I2C bus [duplicate]

I'm planning a hardware design, where I have a main board and multiple peripheral boards. On each of these boards is a microcontroller with I2C, which is the communication bus for the boards. The same ...
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2 votes
2 answers
331 views

Multiple slave I2C on different power rails

I read following threads, but still there are some unclear parts for me. Multiple I2C devices with the same address I2C Pull-ups with Multiple Power Supplies Design for Multiple I2C slave devices I ...
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Looking for data sheet of the following Modbus Sensors #updated

I'm a noob in this area, please ignore any stupidity and lack of info and any help is appreciated and I'm ready to provide all clarification on the post if by chance any info is missing. So i have ...
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Stm32f103RB does not send data in Full duplex SLAVE SPI mode

I am working on stm32f103rb nucleo board and want to send data and receive data using stm32f103 in slave mode. I can get data from the master but I can not send data to the master. I do not know what ...
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What is the slave address of the STM32 NUCLEO-F401RE?

I am currently trying to learn I2C communications with two STM32 NUCLEO-F401RE boards and I am having trouble on how to figure out the slave address of the board. I searched the datasheets and the ...
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2 votes
1 answer
1k views

I2C bus extender

I am working on a project which requires a long I2C bus which can be long as 200m or more.I searched on the internet and found a chip nxp PCA9600.I would like to know is there any alternate for this ...
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2 answers
357 views

No Acknowledgement from slave device

I am using a FTDI's UM232H usb-i2c adapter to communicate with MAX6615 temperature monitor device and DLVR pressure sensor. I developed a I2C routine to talk to these above mentioned devices. I can ...
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STM32 SPI Slave send data Problem

I am working on a project with the STM32F411 microcontroller. It is set in SPI slave mode and receives data without any problems. When I want to send data over the spi peripheral i works sometimes but ...
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I2C - Certain Slaves not Pulling the Lines down fully

I have a large number of boards deployed with a TI CC3200 microcontroller and a variety of sensors for an industrial monitoring application. I have been having an issue for some time now, on some of ...
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What is slave select signal on the APB bus for?

I am currently working on an APB BFM and I have a question regarding the bus protocol. I understand every slave on APB bus has its own unique address space, where its internal registers are mapped. ...
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Arduino-to-Arduino SPI unexpected characters

I've been trying to follow the posts on Nick Gammon's page which are admittedly a bit old, but seem to be everyone's recommendation for trying out Arduino to Arduino SPI. I'm able to get ...
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-1 votes
1 answer
632 views

PIC SPI Master and Slave at same time

I need to implement a SPI slave device, and SPI master, the idea is a SPI "middle man". I'm familiar with avr and mbed development, i lost the contact with PICs long time ago, so this will an ...
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-1 votes
2 answers
295 views

i2c communication problems unless test equipment is attached

I have a RaspberryPi acting as a master for an Atmel ATTiny861A slave over i2c, continuously sending a command plus 3 bytes of data to light an RGB LED. This works perfectly but ONLY if the AVR ...
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USB OTG port in slave mode, possible to use USB-A ports in host mode simultaneously?

I have been researching USB OTG for a little while and was not able to find an answer to my question. I'm seeking for the conditions, if it's even possible, under which I can have one USB OTG port ...
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3 answers
1k views

How can I connect BeagleBone to 2 slaves with 1 "Chip Select" pin?

I have a BeagleBone white and I want to use it as a master which is connected to 2 slaves via an SPI connection, besides SCLK, DIN, and DOUT there is one pin of chip select "CS" "just one" and I need ...
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How do I2C modules select between more than 2 slave addresses?

I am using the TMP112 I2C temperature sensor and noticed that you can choose between 4 slave addresses by connecting the A0 pin to V+, GND, SCL, or SDA. How does the sensor tell between SCL, SDA, and ...
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Not enough digital outputs for SPI slave select lines (CS#)

I have a microcontroller with only 4 digital outputs available and 4 digital inputs. The problem is that I need to communicate with at least 4 SPI devices (ADC's and DAC's). 4 SPI devices means 2 ...
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Regarding SPI Slave Selection?

Consider that an SPI has more slaves. Suppose if more than one Slave wants to communicate with Master simultaneously then How does an SPI react in that situation? by means of priority or any other ...
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5k views

stm8s I2C Communication [closed]

I want to use I2C Communication between two stm8s208cb MCUs. I use stm8s standard peripharel library. My code: Master: ...
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1 answer
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Modbus Rs-485 serial communication and polling with reference to manual

I have connected my slave and RS-485 using serial connection and using my computer as master device. I'm able to poll but I cant figure out which registers I'm polling as shown in image 1. I tried to ...
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1 answer
205 views

SPI communication with multiple slaves

I am working on a project that is using an ATtiny861A and this only has one SPI. If I want to hook up a radio and an external memory to the same SPI, will there be an issue sending data from the ...
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3 answers
230 views

usb to rs232 to usb

I have a system where there is usb slave device that is in a rotating structure behind a slipring. I need to pass the signal through the slipring (we only have 4 "wires") and onto a computer. Due to ...
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libmodbus trouble with reading from slave

I have the following code for connection to a temperature sensor as my slave using the libmodbus library in C, ...
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Using nRF8001 as a master with an FPGA

I would like to use Nordic's nRF8001 modules in Master and Slave modes and also would like to connect it with Spartan-3E FPGAs using SPI. I am considering buying the nRF8001 DevKit. I believe it is ...
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USB OTG: Possible to perform emulation of slave device on master with drivers recognized?

I'm not exactly sure if this should be under a separate StackExchange topic altogether (programming maybe?), if it is, please move it and sorry for the inconvenience. I'm planning to build a device ...
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How can we find the clock frequency (SCK) set by master from slave in SPI

How can we (in software, no probing using CRO) know what clock frequency the Master applies from slave (assuming I have no prior information of this). In general I program the Div_Reg register and I ...
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6 votes
3 answers
5k views

Are any USB-to-SPI *slave* bridge chips readily available?

I would like to interface a battery-powered device to USB, without requiring users to install drivers. Data transfer requirements are moderate, so the ~60kbytes/sec of HID mode would be fine, but I ...
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3 votes
4 answers
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AVR SPI target with interrupt

For a project, I want to have two microcontrollers talk to each other via an SPI interface. I wrote the following code for the target microcontroller: ...
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1 answer
607 views

high value resistors in optical slave trigger? Why?

In a commercial optical trigger, for triggering flash units remotely using the on camera flash, there are very high resistors two 30Mohm in series. Why such a circuit would need resistors so big? This ...
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