Questions tagged [communication]

Exchange of information between devices. Communication can be wired or wireless.

184
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8answers
31k views

Why does USB have 4 lines instead of 3?

USB specifies 4 pins: 1. VBUS +5V 2. D- Data- 3. D+ Data+ 4. GND Ground Why is this not 3? Could the Data and Power not share a common ...
161
votes
4answers
217k views

USART, UART, RS232, USB, SPI, I2C, TTL, etc. what are all of these and how do they relate to each other?

As a novice electronics hobbyist, I have heard these terms and more being thrown around everywhere. At its root, I understand that they are all based on communication between devices, computers, ...
77
votes
3answers
125k views

Difference between UART and RS-232?

Most of the time RS-232 and UART come together in serial communication theories. Are they both the same? From my readings I concluded UART is a hardware form of the RS-232 protocol. Am I correct?
61
votes
3answers
8k views

How does my screen driver handle so much data?

I just did some quick calculations: On my MacBook I have a resolution of 2560x1440 multiplied by 24 Bit for colors we get 11.05MB for a single picture or 663MB per second at 60 fps. I guess there is ...
50
votes
2answers
20k views

In a USB cable, is it OK to swap the D+ and D- wires?

I heard that D+ and D- are differential signals, does it matter if I swap them when connecting a USB device to the computer?
43
votes
7answers
10k views

Why aren't headphone jack shaped plugs used for data?

With Apple's lightning cable, and USB 3.0, reversible cables are taking off, and I personally think this is very convenient. But we have had better than reversible for a long time, in the form of the ...
39
votes
2answers
12k views

Why are USB devices slower than 480 MBit/s

Motivation With a signaling rate of 480 MBit/s USB 2.0 devices should be able to transmit data with up to 60 MB/s. However today's devices seem to be limited to 30-42 MB/s while reading [Wiki:USB]. ...
33
votes
13answers
16k views

Software to create timing diagrams

In my professional life, I sometimes need to create timing diagrams for protocols: UART, SPI, etc. However, I can't find any good programs available. What programs can be recommended for this and what ...
27
votes
8answers
3k views

When should one switch from ASCII to advanced serial protocols?

All my microcontroller devices that communicate with the PC via UART use ASCII strings for sending commands and receiving data (as implemented in Arduino). That's what I learned when I began digging ...
24
votes
3answers
7k views

How is 255 Tbit/s processed in optical fiber communication?

I have never understood how the new record breaking data transfer speeds are achieved in terms of converting from/to electrical and optical signals. Suppose we have 255 Tbits of data and we want to ...
24
votes
3answers
2k views

Why is the reflector on this millimeter-wave antenna spinning?

The WIRED YouTube video Inside Facebook's Quest to Beam the Internet Via Solar Drone and article Inside Facebook’s First Efforts to Rain Internet from the Sky show a dish antenna (starting after 02:00)...
22
votes
11answers
25k views

Injecting a communication signal over DC power supply lines

I'd like to be able to daisy chain multiple devices using just the power supply wires and then inject a communications signal over the power lines to turn it into a half duplex network. Are there any ...
22
votes
6answers
8k views

Serial protocol delimiting/synchronization techniques

As asynchronous serial communication is widely spread among electronic devices even nowadays, I believe many of us have encountered such a question from time to time. Consider an electronic device <...
21
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8answers
4k views

Is it possible to receive information if the received power is below the noise floor?

This relates to my previous question, which I think I have asked in the wrong way: How to insert background EM noise into pathloss equation? I wasn't really interested in detectability of the signal,...
21
votes
5answers
8k views

Why do people use AT commands in serial communication?

I need to know why people in embedded systems use AT commands? When I have asked people say that it is a standard. So my question is: What does "AT" means? Why do people keep saying it's a standard?
21
votes
6answers
2k views

What drives the advancement towards ever faster cellular network speeds? [closed]

I've always accepted that technology advances. Being born in the 90s, everything just becomes faster, smaller, cheaper and generally better if you wait a few years. This was most obvious with consumer ...
20
votes
2answers
518 views

“56k modem” found in VHF band

While scanning the VHF spectrum with a SDR USB dongle, I found something that sounded like an old 56k modem (at around 160MHz, FM modulation, Europe region). After some research, I found out that is ...
19
votes
8answers
33k views

Communication between multiple microcontrollers

I'd like to start implementing a system consisting of N microcontrollers (N >= 2 MCUs), but I would like to know the possibilities to let them communicate one with the other. Ideally, (N-1) ...
19
votes
3answers
5k views

Dual-SIM phone, do they use 2 GSM modules ? Anyone has high level schematic?

As an slight extension of my project, I am trying to see if I can improve connectivity resilence by using a dual-SIM approach. Dual-SIM phones (or Tri-SIM, quad-SIM phones) are quite popular in many ...
18
votes
8answers
60k views

Is CAT5 cable good enough for RS-485 vs “true” RS-485 cable

I have a serial comms project coming up. A number of boards with RS-485 interfaces need to communicate. Date rate is 57600bps and cable length will be less than a few hundred feet. Will shielded ...
17
votes
5answers
59k views

Difference between Hz and bps

Does Hz and bps mean same? Can a signal be transferred at rate of say Mbps on a channel bandwidth of few Khz?
17
votes
2answers
13k views

transmitting 5v signal over a long cable

I'm seeking for help here as I need a reliable answer to this. I need to get an input signal (low frequency 5v digital pulse), to a micro-controller from a (...
17
votes
3answers
29k views

What's the maximum CAN bus frame (message) rate at 125 kbit/s?

My CAN bus is running at 125 kbit/s and is using extended frame format exclusively. I would like to know what's the maximum rate of CAN frame I can send out. Suppose the data length is always ...
17
votes
2answers
2k views

Why not use a ferrite bead around an RS-232 cable?

This is from the instruction manual of a printer: As you can see, one is not supposed to wrap the supplied bead around the serial cable. What is the reason for this?
15
votes
4answers
30k views

Why the conversion to Intermediate Frequency?

While studying about various communication systems (Superheterodyne receivers and Television receivers, to name a few) I often come across blocks that convert RF signals to Intermediate Frequency (IF) ...
15
votes
3answers
4k views

How can over 24 GHz communication be possible?

I read the article Google wants the US' wireless spectrum for balloon-based Internet. It says to use over 24 GHz frequency spectrum for communication. Is it ever possible to generate that high ...
15
votes
6answers
8k views

Wireless communication between more than two Microchip PIC microcontrollers

I would like to create wireless communication between Microchip PICs for my simple project. It's actually an one way communication but there is one server and more than one client (about 2-4, all ...
15
votes
3answers
323 views

Communication among briefcase halves

I'm building a small laptop-ish device in a briefcase. Imagine the green wires aren't there. The LCD half lies somewhat deeper in its case than the keyboard part. For now, testing and programming, I'...
14
votes
7answers
30k views

Hyper terminal equivalent in windows 8 [closed]

I need to do some communication between 8051 micro-controller and PC . There used to be a hyper terminal for this purpose in windows XP. I m using windows 8 now. So can anyone suggest me some ...
14
votes
4answers
5k views

ESP8266 - is it used in real industry? [closed]

I wonder if ESP8266 or similiar (ESP32 for example) modules are used often in real mass production in medical/automotive/military/households industries. I see many DIY projects with it, but there is ...
13
votes
7answers
5k views

Is it possible to send multiple data bits on a single wire at once?

Is there an existing protocol or modulation method where multiple data bits are sent over a single wire at once or maybe an additional ground line (like serial communication)? I know there are ...
13
votes
9answers
10k views

Why Decibels are used to measure Signal to Noise Ratio?

We just started a communications course in college and we came across SN ratio. The following is an ambiguity I am facing which my professor is unable to resolve: Signal to Noise Ratio is the ratio ...
13
votes
3answers
22k views

UART receiver clock speed

I was trying to understand UART fundamentals.It is understood that It is an asynchronous communication protocol and hence the TX and RX clocks are independent of each other The data reception is ...
12
votes
8answers
23k views

Wireless communication over long distances

Would like to communicate between an Arduino and a PC but over a distance of 2500+ feet outside in the open, wirelessly. What would be the best way of doing this? The communcation devices I have ...
12
votes
3answers
2k views

How much power do I need to transmit a radio signal through a solid ice crust 100 km thick?

Imagine I put a floating probe inside the subglacial ocean of Encelado or Europa: how much power should my radio have to be able to communicate from external surface with the probe? Or, in different ...
12
votes
4answers
7k views

Implementing a CAN protocol layer in software

Background I'm developing a project which will require the modest microcontroller specs of: 8 12-bit, 10kHz ADCs 1kB of RAM 48-QFN or smaller footprint 20kbps daisy-chainable noise-resistant and ...
10
votes
3answers
2k views

Selecting a network layer over CAN bus

I am planning on using CAN bus in an industrial automation application, however I'm having a hard time deciding how to implement the network layer. Does anyone here have any recommendations for a ...
10
votes
3answers
4k views

Do all PHY Ethernet chips have a hard-coded MAC address?

For example, this TI PHY chip DP83630 has two MAC addresses that can be used as destination and source MAC addresses for PHY control frames. (page 72 and 94) Does this means all PHY chips will have ...
10
votes
4answers
473 views

Sharing and Notating Schematics?

So a friend and I were talking about schematics at work and how we can better communicate among us and our co-workers. I know Kortuk had asked a question previously that was similar, but that question ...
9
votes
6answers
10k views

Good RS232-based Protocols for Embedded to Computer Communication

I'm working on a project that involves a good bit of data communication between a remote Arduino and a computer. The wireless connection is through a pair of XBees, so we have a RS232 link between the ...
9
votes
4answers
1k views

Communication between microcontroller and separately powered PCB

On one board I have a microcontroller with one power supply and on another I have a Flip Flop with a separate power supply. I want to connect a pin of the microcontroller to the reset pin of the flip ...
9
votes
4answers
3k views

How long between Arduino digital pin and IC?

My current project involves using 74HC595 shift registers to control an LED display, however the display could be up to 5 or so metres away from the Arduino board. The plan is to use some DB9/RS232 ...
9
votes
4answers
1k views

Is this communication I²C?

I need to decode communication between two devices, but I have no information about these devices. All I know is that four wires are needed (GND, VCC and two wires of communication). I suspect that it ...
9
votes
3answers
17k views

Measuring the phase difference between two signals

I'm looking for an analog method of measuring the phase difference between two signals operating at frequencies in the range from (0 - 20 MHz). I'm wondering if there's an IC that does that or a ...
9
votes
4answers
1k views

Why the integral is zero

I wonder why under assumption that \$\omega \gg \frac{1}{T}\$ then \$\int_{0}^{T} \sin(\omega t)dt \approx 0\$? Since the integral should be like \$\frac{\cos(\omega t)}{w}\$ from \$0\$ to \$T\$ and ...
9
votes
5answers
1k views

Visible light communication receiver

I am a student and I have to design a visible light communications project. The requirements are 20 cm distance between the receiver and transmitter, 20 kbps/s data rate and it must work in an already ...
9
votes
4answers
2k views

What is a good communicaton device among teensy and arduino besides “XBees”

I have been using XBees to communicate my teensies so far. However, as you know, XBees are really expensive and when I want multiple devices to communicate with each other, I have to pay for several ...
8
votes
9answers
3k views

What are the ways I can make my circuit communicate with a computer?

I am a novice at electronics hacking. I would like to know how I can make a circuit communicate with a PC. Take for example, a simple circuit, with one LED and a switch. The switch on the circuit ...
8
votes
5answers
3k views

How fail-safe is \n\r as stop bytes?

In my UART communication I need to know the start byte and the stop byte of the message sent. The start byte is easy but the stop byte, not so much. I have implemented two stop bytes at the end of my ...
8
votes
3answers
43k views

Starting with I2C on PIC18s

For a project I'd like three PICs (two slaves PIC18F4620, one master PIC18F46K22) to communicate over the I2C bus. Later on, more slaves may be added (like EEPROM, SRAM, ...). I'm writing the code for ...