Questions tagged [serial-bus]

The process of sending digital data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels.

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Microcontroller requirements for multiple Modbus controllers

I am in the process of trying to design a circuit that will have four RS485 RTU Modbus ports, two acting as masters and two acting as slaves, on which I will connect up to fifteen sensors. I am ...
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Raspberry PI4 and RS232 adapter cable: how to send serial commands

I would like to use a Raspberry Pi4 to control a syringe pump [(see datasheet here and in particular the quick start manual on page1)][1] The connector cables I used are RJ11 from the Pump to RS232 (...
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MAX232 IC does not convert to and form RS232 levels

I made a simple circuit to read data from RS232 lines and print data on different RS232 lines. This is the IC I am using: MAX3232EIDWG4. The IC fails to convert the CMOS to RS232 level logic. I am ...
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How are "async/sync" and "serial/parallel" communications related?

I think "async/sync" and "serial/parallel" are orthogonal concepts. There can be 4 combinations of communication types: async serial sync serial async parallel sync parallel From ...
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Why use pseudoternary here?

Suppose we have this series of bits: 000000100 We use pseudoternary encoding in order to find if the clocks of the sender and receiver are in sync and to correct these mistakes, correct? Can we also ...
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How to identify Modbus device speed rate?

In particular how to identify it without causing device misbehaving. Either new device is being connected, and master has no idea what baud rate the device is configured with (assume it knows about 8/...
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Stand alone CAN bus module or STM32 embedded CAN?

I have spent days studying and trying to achieve simple communications with CAN bus from scratch using stm32f1, but I still have not achieved the desired results and it is difficult to understand and ...
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7 answers
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How does the current of RS485 signals return from the receiver to the sender?

I am planning a system consisting of 1 master device which is connected to 19 slave devices using RS485 transceivers. Also, all devices are powered by 1 PSU. A simplified schematic is shown below. As ...
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Alternatives to CAN for multi-master transmission

As usual these days I'm fighting against component shortage. As in completely redesigning boards since they give us lead times in the 2023 years. At the moment I have this product line where the ...
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SAM3x8e can't program over serial

UPDATE: Jan 2022. I put together a new pcb. This one has the JTAG header and I have an ATMEL-ICE. Otherwise the processor and support layout is mostly the same. I stripped the program down to simply ...
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8 votes
4 answers
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Why common-mode choke on differential-signal serial lines?

I have 2 questions: Why using a common-mode choke on serial communication lines (like CAN, RS485) if the signal is differential? Wouldn't the common-mode noise simply be cancelled in the receiver? I ...
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Can0 return no data, but with no error

I'm actually trying to get data from a CAN on vehicle connected by DB9 on my raspberry. The DB9 provides also energy to the raspberry (here the material that i'm using). I've followed every of these ...
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SPI modes of data transfer

I am learning SPI protocol in serial communications now. I got stuck with the clock phase and polarity controls concept. Why there are 4 modes available other than a single universal transfer mode. ...
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Detect LOW signal in a two-way IO line that's HIGH when idle

I am trying to implement the ISO 7816-3 protocol as can be found in the EMV Co. Book 1 using an ESP32 and MicroPython. However, I noticed that the default state of the I/O line is HIGH, and there's ...
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Serial line behaving strangely

I'm currently working on an Arduino (Mega2560 based) from Industrial Shields. Model is 21+. I use the Serial1 output (TTL 5V) to communicate with a sensor (LP8 CO2) who have CMOS 2,5V serial interface....
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"<ret>" meaning?

I'm attempting to use multicharacter serial commands in this manual (page 18 in the pdf, 16 in the manual), but can't get them to work. When I'm trying to use the "GX " command to move to, ...
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Shouldn't an I2C address be 7-bit binary?

I have a charging IC which I want to use with I2C. In the datasheet on page 31 it says that the I2C slave address is 6BH. Shouldn't this be a 7-bit binary number?
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Need help identifying weird serial protocol

I am trying to decode an embedded serial protocol. The device is a wired remote control for a crane. The controls are obsolete. I'm trying to design a new replacement one. There are a few buttons and ...
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How does I2C handle data loss?

Does I2C have any data loss prevention mechanism? If so, how does I2C recover?
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Inverting Pairs in Full Duplex RS485

The following is the Full Duplex configuration for a Maxim 3292 RS-485 transceiver module. It is possible to invert the polarity of the pairs, lets say, exchange AB by BA and ZY by YZ at the Master ...
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How to record RS-485 Modbus communication at PC?

I am working on a system with an IPC, RS-485 Modbus communication, and 15 Toyo step motors and drivers. A motor frequently moves without IPC intentionally sending moving instruction and causes a ...
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Unable to install MCP2221 Driver on Win10 64bit OS

I use this PIC32MZEF board - https://www.microchip.com/DevelopmentTools/ProductDetails/dm320007. It needs MCP2221 driver tobe installed for UART communication with PC. I downloaded from official ...
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Is it possible (with reasonable effort) to use ethernet hardware to provide point-to-point digital I/O bridge?

I'm interested in designing a "simple" circuit that would bridge digital inputs or outputs over a distance with relatively low latency. The idea is to take several pins from a GPIO bus like ...
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USB to RS485 converter on Linux [closed]

I have a USB to RS485 converter: It has a CH341 chip, that is all I know about it. When I plug it in, I can see that it is bound to port ttyUSB0. I want to be able to send and receive bytes from PC (...
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2 answers
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Unable to upload anything to Arduino Uno

Any time I try up upload a sketch to my Arduino, I get the following error message: That "1 of 10" then repeats all 10 times, and ultimately fails. I know that this board works, as I am ...
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4 votes
2 answers
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What was the communication protocol used on board the Apollo moon lander?

It seems that the development of TTL was contemporary ~1961 the maiden moon landing of the Apollo vehicle, while the development of one of the oldest digital signalling standards RS232 using the UART ...
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What kind of PLL is used to recover the clock from E.G. USB 2.0 data stream

I would like to create a communication protocol to connect two FPGAs. I would like it to be fairly fast, (a couple of 100s of Mbps) but only use a single differential pair. This kind of thing is ...
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Daisy chain multiple PCB with an existing IDC cable

I'm not sure, if I just miss the obvious, but I'm stuck on seemingly simple problem and can't find a solution. I have a series of PCBs, I want to daisy chain. The number is between 8 and 12(max). The ...
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I2C: How does the Master recognize an ACK from a specific slave?

I just started learning about serial communication protocols. So I understand there are only two lines connecting a master and many slaves Master broadcasts the start condition then the slave address ...
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Serial communication protocols used in spacecrafts and airplanes

I always see that CAN bus is used in automobiles for communication between nodes and for on board diagnostics and basically for the overall functioning of vehicle. What are the similar serial ...
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160 views

MIPI I3C Basic Timing: Tsco

The MIPI I3C Basic standard describes an I2C-like bus with different timing requirements. In particular, that document describes a measure, tSCO, that describes a target device's clock-in to data-out ...
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Wired sensor bus technology

I am working on a project which requires a dozen VL53l0X I2C-TOF sensors to be polled by one master MCU over a few meters of cable. Thus, I decided to accompany each TOF by an Atmega8 acting as a ...
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2 answers
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Terminating resistor considerations for half-duplex RS-485 over 80-200 m cable at 115 kbps

I'm designing a system where we are communicating with a device (ultrasonic anemometer) which is at the end of a cable which could vary between 80-200m. The sensor communicates via RS-485 half-duplex. ...
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1 answer
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Bus communication scheme for large number of devices (255+ nodes)?

I'm trying to figure out the feasibility of setting up some type of differential bus communication for up to 400 devices outdoors. The main constraints are mainly power consumption, complexity, wire ...
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1 vote
1 answer
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UART permissible cable length

I am communicating between two esp32's. Can the UART at a baudrate of 512000, work fine over a distance of 1 metre? . The data will be sent at 10ms intervals. Wires are standard 24 awg.
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1 answer
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How to share a digital signal between circuits?

Please see this : The Task I'm trying to create a single module which can safely share a single digital signal. The idea is that each (identical) module can monitor the status of the signal, and can ...
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How would you combine DC power, bi-directional serial data, and an RF signal on a single 50-Ohm coax feedline?

I would like to power a remote device and communicate with it over some serial protocol on the far-end of a 50-Ohm coax feedline (RS232, i2c, SPI, etc), while at the same time sending/receiving an RF ...
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2 votes
2 answers
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How to identify an unknown protocol with a logic analyzer?

I have this Inbras electrolyte analyzer, a rebranded version of the same device manufactured by Diestro. It uses a PIC18F87K22 (master) which communicates with the sensor using a PIC12F629 (slave) ...
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How are DC offset square wave transmission waveforms generated?

The balanced serial transmission shown in the picture is similar to rs485 except that the square wave has a DC offset (e.g. 24VDC) with an alternating offset. The transceiver chip "drives" ...
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ISELED Driver Communication protocol

This is my ISELED Driver Datasheet INLC10AQ & my Microcontroller datasheet S32K142 - 64 pin Microcontroller I have a NXP Microcontroller connected to the above LED Driver. I need to figure of the ...
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-1 votes
3 answers
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Protocol with twisted pair for multiple switch control in a tree topology?

For an irrigation system, I'm interested in simple switches. My requirements: Communication over copper wires, e.g. a twisted pair of cables Nodes(switches) can be set in a tree topology, all sharing ...
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Exactly what is an RTU (Remote Terminal Unit)?

I find the Wikipedia article and other sources ambiguous and I find that the definitions are so broad that I don't know how and when to use the term "RTU". I would like to figure this out because I ...
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How are these Data Buffering Methods same or different from each other?

I am trying to understand the operation of a Serial Bus protocol converter chip. It connects with the serial bus on one side and on the other side it provides its data on the MCU host interface. ...
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How to convert from 2 data line full duplex to 1 data line half duplex?

I'm trying to design a circuit that can convert from a two wire full duplex (think SPI), with one transmit line and one receive line, to a one wire half duplex (think i2c), with bidirectional ...
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Wiring a USB device to act as a Serial port

I'm trying to make a cable that will go from a laptop usb port through an opto-isolator to a 4-pin connector on a circuit board, and I'm trying to communicate via Asynchronous IN/OUT. I have some ...
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3 votes
1 answer
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clock period, throughput and efficiency of I2C bus

If a I2C bus is runs at 400kHz what is the clock period ,data throughput in data-bits/seconds and bus efficiency? i am very new to those buses and is the clock period is 2.5 micro seconds ? any help ...
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A question about UART communication [closed]

Are there predefined keywords/codes that when sent from a pic to a computer running windows (UART) can elicit certain actions (like show a special pattern or open a picture on the screen) on the ...
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1 answer
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3.3V I2C Logic on 1.8V Device

I have designed a board with the ICM-20789, but am having trouble keeping stable voltage values on the I2C bus. Datasheet I have followed the schematic that was listed inside the datasheet, and that ...
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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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Pull up resistor selection for LIN bus

What exactly will happen if I use 1.2K ohms at LIN master node pull-up? Why does the LIN protocol spec recommend to use 1K typically?
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