Questions tagged [serial]

In serial communication data is transmitted as a sequence in time. Main advantage: much less wires needed. Main disadvantage: Higher bandwidth for the same throughput.

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80
votes
3answers
131k 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?
39
votes
8answers
36k views

How to resolve I2C address clashes?

I want to connect multiple I2C slave devices to a micro controller all on the same set of pins but the I2C devices all share the same address. The addresses are fixed in the hardware. Is there any ...
29
votes
2answers
76k views

What are the differences between USB and RS232?

Can someone tell me why people use either USB or RS232. They are both serial ports, right? And I understand that USB is much faster (especially USB3.0) but if people wanted too I'm sure they could ...
28
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 ...
23
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 <...
23
votes
2answers
3k views

How do I make the Fairchild FSA9280/FSA9480/FSA880 BOOT pin trigger? (Samsung Galaxy S)

this is a bit of a long shot but I'm hoping someone has access to the full data sheet for one of the chips listed in the title, and can tell me what combination of VBUS_IN and resistors on ID_CON will ...
22
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?
22
votes
12answers
8k views

Best serial monitor?

I just recently started using a Sparkfun serial LCD. I am able to control it through an arduino, but I want to be able to control it through a terminal on my computer. To be able to move the cursor or ...
19
votes
3answers
50k views

How to read serial data from oscilloscope

I have a microcontroller (PICAXE 20X2) and a pot meter. I programmed the micro so that it sends any change of pot meter to serial port of PC. Obviously it is a 8bit ADC. Now the interesting thing for ...
18
votes
8answers
5k views

Why is serial EEPROM preferred over parallel EEPROM?

In the wikipedia page for EEPROM: http://en.wikipedia.org/wiki/EEPROM it is given that "Parallel EEPROM devices typically have an 8-bit data bus and an address bus wide enough to cover the complete ...
18
votes
9answers
12k views

Ideal WiFi to Serial (or SPI) bridge?

What are some recommendations on an ideal WiFi to Serial bridge? My ideal qualities would be: Simple connectivity, SPI or Serial Reasonable fast speed, at least 1mbit/sec ideally (though probably ...
17
votes
1answer
10k views

With shielded twisted pair cable, do you ground one end, both ends, or neither ends of the shield

I've got a project coming up that's to be doing RS-485 communications over shielded twisted pair cable. The project will involve cable length runs of many 10s of ft and the cables will probably have ...
15
votes
2answers
37k views

How does TTL serial work?

I've been trying to find a good description of the TTL serial "standard" without much luck. I understand that serial transmit (TX) and receive (RX) lines idle high (at VCC) and that they drop to ...
14
votes
3answers
2k views

Difference between real binary value and oscilloscope value

I tried to see an ASCII "A" character with an oscilloscope but the real binary value and oscilloscope values are different why is that? ASCII "A" Binary value - 01000001 The oscilloscope displays ...
14
votes
6answers
51k views

Max Serial Cable Length?

What is the maximum length of serial cable I can use, to connection work properly? Is length of serial cable in connection with baud rate? I am using about 5 meter cable at speed 38400 bauds and RS232 ...
14
votes
2answers
10k views

Serial newbie: why can't I just hook the wires up?

I'm trying to transmit from an ATtiny85 to a PC using Arduino-esque code over a USB-Serial converter without understanding very much of anything. I was shocked and appalled that it did not work. I ...
13
votes
4answers
4k views

Why is the serial connection faster than the parallel connection? [duplicate]

As a software developer the concept of parallel processing usually meant faster processing because it meant things don't have to wait for the other processes to finish if they don't need to. So how ...
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 ...
13
votes
4answers
6k views

How to reverse engineer I2C and SPI protocols?

If I have an unkown device which talk I2C or SPI how can I reverse engineer the protocol. Basically I am looking for something similar as snoop or tcpdump. For software Mac is preferred but can also ...
13
votes
4answers
30k views

How to secure jumper wire connections

Connecting 2 terminals (like Arduino's) via jumper wires does not secure the wires properly. What do you use to ensure the wires do not come loose? Connecting Arduino to the pins at the bottom right ...
11
votes
4answers
1k views

Why is RS-422 interface interference insensitive?

I am trying to understand differences between RS-232 & RS-485. I just don't grasp what is the core principle behind RS-422 inteference resistance? Is it number of wires (4 instead of 3)? Is it ...
11
votes
3answers
13k views

Can the Arduino be used to “spy” on a UART connection between two devices?

I have a need to install an Arduino (actually just the IC) into existing hardware to enhance functionality. What I would like to do is connect the Arduino so that it "spys" on the I/O lines between ...
11
votes
6answers
3k views

How to Efficiently Decode Non-Standard Serial Signal

I'm an undergraduate member of a research team working on a project that involves an RF-transmitting ASIC, and its wireless receiver which should ultimately send data to a PC. The receiver outputs a ...
11
votes
6answers
77k views

capture raw data in COM port

I have a Bluetooth transmitting device and my PC (Windows 7) is connected to it and configured as if it was connected through a RS232 serial port (COM4). How can I capture the raw data transmitted by ...
11
votes
2answers
8k views

Noise (capacitance-related?) in serial signal

The "executive summary" pictures: I want to decode the serial signal coming out of my tablet's headphone jack. This is a somewhat weird "hack" that exists in a few phones and tablets: basically, if ...
11
votes
2answers
2k views

Unit testing AVR assembly language

How do you unit test your assembly code? I'm working on a serial servo controller as part of a hexapod robot project and the code has got to the point where it's becoming complicated ;) Anyway, I'm ...
10
votes
6answers
51k views

What is the difference between Ethernet and Serial communication?

All the mouse movements, USB connections and other PC peripherals such as printers etc. are what is called serial communication. One bit per time. So far so good. But when it comes to TCP protocol, ...
10
votes
1answer
2k views

How serial resistors actually reduce EMI?

I am recently working with a GSM based system, and there was this advice in the datasheet of the GSM module: 22 Ω resistors should be connected in series between the module and the SIM card ...
10
votes
3answers
19k views

High-speed computer interface with an Arduino

I'm planning a project with an Arduino that involves handling a lot of requests from a host computer, and the standard 115200 maximum baud over serial isn't sufficient. I'd like to be able to get ...
9
votes
5answers
2k views

RS232-to-USB Converter [closed]

Anyone have any recommendations on a good rs232-to-usb converter. There are a lot out there and from the looks of it some are hit or miss. Good driver support is a must.
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
6answers
13k views

Resistors in series with Tx and Rx

I'm making my own board and using an ATmega 328 with the Arduino bootloader. I have a DIP switch to select either an FTDI chip (for programming) to be connected to the ATMega's Rx and Tx, or a GPS ...
9
votes
4answers
15k views

AC-coupling capacitors for high-speed differential interfaces

Can you explain me why and where I should put AC-coupling capacitors (usually around 0.1uF) on high-speed (1...5 GHz) differential serial interfaces (like SerDes for Gigabit Ethernet SFP modules)? ...
9
votes
2answers
733 views

How is the fact that the resistor used to limit the LED current dissipates some of energy addressed in lighting applications?

LEDs can't be connected directly to a source of power - only in series with a current limiting resistor. Which means that when the LED is powered some power is dissipated by that LED and some power is ...
9
votes
3answers
26k views

Firmware & Circuit of ATtiny45 direct USB 2.0 Connection

I want to make my own modular USB device using an ATtiny45 that simply sends data to the PC over USB. I'm not reading data, so a single way ( ATtiny -> PC ) connection would be completely okay. I am ...
9
votes
2answers
3k views

How to make a fingerprint scanner (UART, Serial) for a headphone jack on Android?

Square up reads magnetic stripe cards through headphone jack on both Android and iOS. I want to capture fingerprints on an Android phone. Can I develop a hardware to capture fingerprints in the same ...
9
votes
1answer
5k views

MIDI IN : many circuits

I'm building a MIDI IN to serial port RX cicruit (for Raspberry Pi, or Arduino, or anything else...) using a 6N138 optoisolator. But I find many different circuits, I don't know why there are so ...
9
votes
6answers
39k views

How can I fix an AVRdude not-in-sync error when programming Arduino via USB-to-serial cable?

I'm trying to build this Ambient lighting for PC. This worked flawlessly on my Arduino Uno. My next step was to make it using "Arduino on a breadboard". So I bought a blank ATmega328 chip and burned ...
8
votes
2answers
373 views

Can an SPI slave start a transmission in full-duplex mode?

As far as I know, SPI transmission for an SPI slave works like below: Master selects a slave using SS pin Master and slave send data to each other simultaneously Master starts clock and data ...
8
votes
3answers
3k views

MSP430 serial communication failing in cold weather

I have a product using the MSP430 microprocessor, which has been selling for a couple years now. One of the MSP430's jobs is to communicate over async serial to a low-power radio. With the onset of ...
8
votes
5answers
866 views

What is the most popular embedded serial bus? [closed]

I'm designing an embedded device that I would like to make interoperable with third party peripherals through a serial bus. Should I choose SPI, I²C, or some other bus? The peripherals will be ...
8
votes
5answers
28k views

multiple arduino communication (1 master, n slaves)

I would like to develop a master/slave network that consists of: 1 Arduino master that reads sensors and generates velocity ramp profiles based on the sensor signals and then sends those ramps to ...
8
votes
2answers
1k views

Does a baudrate in serial communication (USB or RS232) need to be exact?

In serial communication, does the baudrate mean we have to use the exact clock speed or is it a range of speeds that we can use? and if it's an exact value, how exact should it be ? for example, can ...
8
votes
3answers
5k views

What is the purpose of 8b/10b encoding?

In the physical layer of USB 3.0 there is an 8b/10b encoder. Wikipedia says that this eliminated DC offset, while the tutorial I am reading says it is a common encoding scheme in high-speed serial ...
8
votes
2answers
4k views

Implementing Control Commands for an MCU over Serial

Im looking to integrate a command interface in a project that im making that will accept commands overs serial from a PC. The idea is that the device will do its thing but it gets sent a command, it ...
8
votes
1answer
462 views

Is a 10GHz clock required to drive a 10Gb serial pin?

I am reading about the 10Gb/s Ethernet PHY for Altera FPGAs (datasheet here). I was impressed to know that, at the hardware level, the 10Gb/s is done serially. Naively, I would think to do 10Gb/s ...
8
votes
1answer
4k views

Upload to an Arduino from the command line

If I have a sketch compiled to hex, is it be possible to upload this sketch to an Arduino board using avrdude directly from command line? Pekkaa figured out that arduino ide executes the following ...
8
votes
1answer
1k views

Arduino serial communication protocol design

I make a drum sequencer interface for electronic music. It uses an arduino mega as it's microprocessor, and currently it interfaces to a Processing program that I wrote for serial communication. From ...
8
votes
1answer
166 views

Unexpected Atmega16 response over UART

Unexpected Atmega16 response over UART Brief problem summary I have flashed an Atmega16 with code that should result in the Atmega16 sending back whatever character I send to it via a terminal. I ...
7
votes
3answers
11k views

A simple on-circuit RS-232 to USB converter

I want to interface a PIC microcontroller (18f452) to a PC via the USB port. I learned that there is a USB class for serial communication so I will not have to write device drivers for it. I want to ...