Questions tagged [protocol]

A protcol is a ruleset for formatting and exchanging messages.

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35 views

How does USB C PD to DC power negotiation work

I have a battery and would like it to output power from its USBC PD to a DC input device. The device has a fixed resistance and the device must receive 20V fixed. How can I do this?
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4answers
1k views

Does the SPI protocol specify how many clock pulses a master device should send to the slave?

I'm trying to implement an SPI device in Verilog. I'm having a lot of problems for coordinating master and slave, since sometimes (with my current impl.) the SPI master device doesn't send enough ...
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4answers
79 views

Rs485 A & B Labels being used inconsistently

I would like to know if there is an official standard with regards to rs-485 terminals being labelled A & B. I have always believed: A=> + (positive) and B=> - (negative) however, I have ...
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Figuring out communication protocol

Complete beginner trying to learn by doing here... Background: I have a wine cooler (for beer) that I want to remote control the lights on by adding a microcontroller. I'm planning on using a ESP32 ...
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1answer
76 views

What is the interface type of this LCD?

I'm trying to find out if this LCD uses eDP, or MIPI DSI, or something else so that I can choose a replacement LCD, and I'm a beginner at this. I wasn't able to find it on the manufacturer's website, ...
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1answer
80 views

Why does SAE J1939 Commanded Address requires a delay when sending multiple package message?

I wonder why the command Commanded Address from SAE J1939-21 protocol, requries a delay between 50-200ms for every multiple package message for the transmitter. Why? Does the microcontroller unit not ...
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1answer
35 views

Do all flash memory chips pinout layout and usage follow a specific standar(s) and protocols?

As I see in this question I see that WINDBOND W25Q128FV has similar pin inteface/layout with the Maxronix MX35LF1GE4AB. Therefore, the following question came to my mind, do all flash memory chip ...
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2answers
459 views

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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1answer
68 views

Help to identify CAN packets of a lift-fork

I have monitored the CAN bus of a lift-fork but I can't recognize the meaning of the packets that was being sent periodically on the bus. Do somebody have an idea on how to interpret these packets ...
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1answer
84 views

CAN Bus Hardware Design with 1000 nodes

I am looking to develop a CAN Bus System employing up to 1000 nodes on a single network. I am using an existing design based on STM32F072CB that has the CAN Controller embedded along with TJA1050 as ...
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What is the difference between AR/AW/ACSNOOP in AXI & ACE?

I'm exploring AXI and ACE protocols and I found 3 different appearances of a SNOOP signal: ARSNOOP AWSNOOP ACSNOOP I can't get the purpose of the 3 different lines with the same(?) signal. At least ...
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168 views

Shownig RTNETLINK answers: Operation not supported while setting CAN bus modes

I'm new to CAN bus and I'm trying to write some data frame on CAN bus from a CAN node to another CAN node. I have enabled CAN device driver through my build source. But whenever I try to select mode ...
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1answer
68 views

J1939 - Source Address field and Address Claim for a diagnostic/scanner board

I have a board that include CAN hardware, I would like to use it to scan some PGNs of the J1939 protocol on a fork-lift. This is the packet: Below we have the the PGN 65262. Considering that all the ...
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1answer
33 views

ASi (AS-Interface), understanding Power Supply

Can somebody help me understand the ASi (AS-Interface) power supply. I think I understand how the data decoupling works (because of the induction voltage of the inductor). But I dont understand the ...
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1answer
62 views

What is the meaning of pulling a pin HIGH (of an IC)?

Let's say I have a microcontroller (ESP8266) driving a DAC via a I2S protocol. So the ESP is connected with 3 pins to the DAC, and sending the data to it throught these pins. But I wonder, how exactly ...
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1answer
28 views

BLE emission when disconnected and waiting connection

I'm working on a toy device that goes into an airplane. It is using a BLE device and yet my knowledge about is a quite limited. If I understood correctly, usually in protocols: the device advertise, ...
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1answer
67 views

CHADeMO protocol understanding

I want to know specification for CHADeMO standard,its a fast charging method for electric vehicle upto 400 kW preparing 900 kW on the map.I tried searching data for CHADeMO but just found above ...
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1answer
89 views

How should I interpret this CAN bus protocol - J1939

I have been using J1939-21(Data link layer) many times, but now I'm confused. First I know that a J1939 protocol is build up from a data frame and that data frame looks like this in practice. ...
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1answer
124 views

Figuring out transmission protocol in cheap wireless door bell

Due to boredom I've tried some reverse engineering of simple cheap wireless ring bell which uses 433.92MHz transmitter and receiver via OOK modulation. It sends several times the same information. On ...
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1answer
1k views

Teraterm to show hex data [closed]

I am getting UART data from micro-controller to PC. Micro-controller sends data in hex(eg.0x1B) format which can range from 0x00 to 0xFF. I want teraterm to display the received data in hex format. Is ...
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1answer
51 views

spy/monitor and decode spi protocol between master and slave

I often find my self in a situation when i need to debug systems of a MCU and other device which comunicate by SPI interface. most of the times we use a logic analyzer between the master and the slave ...
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1answer
126 views

Still confused about SPI implementation FIFO to buffer

Point 2 of page 16 in this document (image shown below) states that: The contents of SPIxTXB are moved to the shift register SPIxSR Exactly how is it moved, is it moved serially or in parallel? I ...
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50 views

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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1answer
73 views

Logic analyser reads bits as if they are shifted left by 1 bit, what could be the issue?

The logic analyser is from Hobby Electronics, and is being run on the PulseView software. It is not reading the data correctly. All of the bits are shifted one to the left so everything is read ...
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58 views

Communication protocol analysis via microcontroller board

I have an idea for my master's thesis. I want to make a communication protocol analyzer and monitor the data on a PC via software I coded. For the first stage, I need a kind of data acquisition system ...
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1answer
67 views

What are the modern uses of SPI and I2C protocols [closed]

I have been using I2C and SPi for a few years now, but as I begin working with USB, I realize it is much faster. I still see devices with 2 MCUs that could potentially communicate faster with USB, but ...
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1answer
91 views

Why does bluetooth (still) only support pairing two devices?

When bluetooth was first devised there was typically only one device to connect to at a time so it was quite natural to just implement a pairing protocol. I believe we are now on Bluetooth 5 Why is it ...
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0answers
149 views

Which differential protocol to use when redriving Ethernet?

I want to redrive a 100-BaseTX signal on a board. The signal is to be redriven 3 times (by the same setup). On one end is a STM32 NUCLEO-F767ZI board, and on the other end is a GbE switch including ...
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1answer
118 views

"smart" label on home gadgets package and mcu [closed]

Are any home gadget that is written "smart" on the packaging, capable to interact with a microcontroller through some protocol or "smart" label is just another marketing ploy?
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2answers
100 views

How to find and decode a particular protocol

I'm trying to understand what protocol is used on a particular device in order to decode it and send custom values. So far I was able to record the data with a logic analyzer but couldn't figure out ...
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1answer
70 views

RS485 communication issue

I have used PIC18F45k40 device for RS485 communication. I have 2 ckts one is isolated and another non isolated RS485 design. I have schematic & placement for reference. I have connected multiple ...
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1answer
81 views

Address-free communications between microcontrollers in any topology

Suppose I have 9 microcontrollers each on their own PCB, connected in a square grid. Is there a way I can get a single node to communicate to all the other nodes, be able to address them individually, ...
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1answer
88 views

Frequency Key Shift technique to superpose the digital communication on top of 4–20 mA signals

I start working with HART devices and I really try to understand how digital data is transferred trough 4-20ma current loop. I start read this article: https://instrumentationtools.com/hart-...
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1answer
92 views

What are examples of complex communication protocols that do not need a 7 layer OSI model to describe them? [closed]

I am trying to dissect an existing design of a custom communication protocol that shall make use of infrared pulses to communicate between only 2 devices. The design is architected in such a way that ...
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0answers
201 views

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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6answers
855 views

Logic analyser or oscilloscope? [closed]

I am an embedded enthusiast and very much into embedded C and firmware development. I love to interface different sensors and modules to MCU by creating my own libraries from scratch. Now for ...
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1answer
172 views

What is "Pointer" in DM14 at J1939 CAN-bus standard?

What is "Pointer" in DM14 at J1939 CAN-bus standard? Can it be the memory Address[DEC]?
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1answer
81 views

Help using usb c to power display

Here is a bad diagram of a project I’m working on. In a beginner to EE and this stuff. I have a laptop display connected to a controller board I got on eBay. It has a input of hdmi and a dc power jack ...
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0answers
59 views

Splitting pins on USB-C

I’m new to EE and I have a project I’m working on that has confused me. I have an old display from a laptop that I want to make into a custom 2nd monitor, I bought a driver board for that model ...
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1answer
288 views

J1939 - CAN BUS - What is ECU and ACU?

I have a question about the CAN-bus protocol J1939. What is ECU and ACU? Assume that we have three motors that can be controller via J1939. Each motor have it's source address 0x80, 0x81 and 0x83 and ...
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1answer
375 views

I2C hold master mode Vs no hold master

Suppose to have a I2C device like Sensirion sht21, the datasheet says that the sensor supports both hold master read mode and no hold master read mode. In addition to that, suppose that the library ...
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2answers
564 views

Rinnai water heater power and communication interface/protocol

My Rinnai tankless water heater can be connected to a wifi module that controls the recirculating pump and other functions. The only connection between the PCB of the water heater and the external ...
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1answer
389 views

Trying to control vintage amplifier (TEAC A-H500) with Raspberry Pi - what's the communication protocol? 8-bit bus?

I'm trying to control my vintage amplifier from Raspberry Pi - I want to create a nice little Spotify streamer that on playback start will automatically turn on the amplifier and set the input ...
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2answers
621 views

How many devices can be daisy chained via SPI/I2C?

How can we determine how many devices can be daisy chained from a datasheet
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1answer
283 views

What IR Protocol is this?

This was found on a window fan remote control. The fan is a Bionaire BW2300 It seems to have no AGC leader, 12 bits, my guess is each bit is either: ~420us on + ~1260us off ~1260us on + ~430us off
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2answers
548 views

Are there any advantages to an inverted serial prototocol?

Why would someone implement an inverted serial protocol? Are there advantages in doing so? One obvious disadvantage seems to be that an extra device needs to be included in a circuit if the ...
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3answers
799 views

Analyze protocol used for Futaba VFD display, 3 data pins

I take apart a Samsung SMT-C7140 HD Unit (made obsolete by cable company, a shame) and found a nice display that I could probably reuse. It is a Futaba GL07-00006A (13-BT-246GINK). I tried to find the ...
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0answers
64 views

Is there really a proper way to send private bits even 1 with CANBUS?

I was thinking of making an authentication protocol for canbus. Is there a way to send even 1bit privately to another node ? Have seen many implementations quite a few good ones. In particular ESA ...
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1answer
237 views

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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1answer
137 views

Some Physical Layers used with OBDII

I need to review some physical layers used in OBDII, a very common interface communication of vehicles and used as interface in a automotive scanners. I don't need exactly to know how the protocol ...

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