Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [uart]

A UART (Universal Asynchronous Receiver Transmitter) is a piece of logic that sends and receives data on a serial port.

A UART is often used with communication standards like RS-232, RS-422, or RS-485. Usually 8 data bits are sent, but other word lengths are used too (5 to 9). A UART usually contains a clock generator, input and output shift registers, and transmit/receive and read/write control logic.

Further reading:

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What standard UART rates are there?

I know 9600, 19200, 38400, 57600, 115200 and 1.8432 Mbaud, but no others. Why are these values used, and is it simply doubling each time or is there something more complex going on (for example, 38400 quadrupled is not 115200 baud?) The reason I…
Thomas O
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Pull up resistors on UART

I was going through an app-note AN2606 where I came across this connection diagram: As per my knowledge, UART is push-pull type and Tx provides the pull-up required and hence we don't need to use any external pull ups. Am I missing something here?
Whiskeyjack
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One or two UART stop bits?

UARTs often let you choose between 1, 1.5 and 2 stop bits. With 1 stop bit payload efficiency is 80% (8/10), with 2 stop bits that drops to 72.7% (8/11). So what's the advantage of the second stop bit?
Federico Russo
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When should I use USART instead of UART?

I want to make a communication between my PIC18F4550 and my PC but I'm getting stuck whether I should use UART or USART for long distance. When it's more advantageous to use the one instead of the other one?
Tata Simano
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Handling of UART Errors

I am not concentrating on a Specific MCU as UART of most controllers has similar architecture. They have FIFOs for Both Tx and Rx. Most common errors generated by UART are:- 1. Framing Error 2. Parity Error 3. Over-run Error (Overflow of Tx/Rx…
Swanand
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Detecting start bit in software UART

I'm experimenting with writing a software UART on my microcontroller using GPIO pins. This is to temporarily add a UART channel on a project until we get the new design implemented that uses a uC with more UART ports. What I'm having difficulty with…
Dan Laks
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Are CTS and RTS necessary on UART port?

I am currently working on a project where we use TIVA C TM4C123G and I am currently getting inspired by launchpad as reference design. I have several UART peripheral to connect to the main chip using UART, however on the pins of the chip RTS and CTS…
user92481
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Why do baud rates need to be same in asynchronous communication?

As far as I know, TX and RX pins operate independently. On the other hand, experimentally I get garbage reading if the baud rates of a lets say MCU and a PC are different. Is there a way to explain this for a non-expert?
GNZ
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What's the meaning of "x" in RxD and TxD of UART?

RxD means Receive Data. TxD means Transmit Data. Where the "x" come from?
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Is it OK that I accidentally swapped TX and RX on a UART bus?

I accidentally swapped the TX and RX pins on a UART bus when hooking up a to a 3.3V bus with this 3.3V cable: https://www.sparkfun.com/products/12977. Did I cause any permanent damage to this board as I debug it? Can we all agree to use TXO, RXI?
tarabyte
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Why stop bit in UART?

UART frame has 1 start bit, 8 bit payload data, 1 or 2 stop bits. Frame structure and baud rate is agreed by both transmitter and receiver for successful data transmission. Start bit is used to synchronize and tell receiver that frame is started.…
Avadhana Technologies
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Sending "larger than 8-bit" quantities over an 8-bit link

I have data that I logically manipulate in 12-bit quantities which I need to move over an UART link. (actually soft-serial from Mbed to PC over USB cable, but that's irrelevant) I was thinking about using the common 8N1 (8 data bits, no parity, 1…
GummiV
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Is RTS & CTS important in UART communcation

I am starting with UART communication in PIC32MX795F512l. This UART will communicate with PC. I was just wondering that it is important to connect RTS & CTS or just connecting Rx Tx GND will make the communication? Some websites say RTS & CTS are…
Aircraft
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does changing UART stop bit number configuration (receiver side) affect message correctness

I'm using USART on board to display messages on desktop PC terminal using Realterm I noticed that, when I change stop bit number on Realterm, it does not affect the correctness of the message, contrary to baud rate, or bit number. why stop bit…
Lkaf Temravet
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Why do I need to use multi drop bus protocol (MDB) in vending machine and How?

I have a project to build a vending machine but I am suffering from Scarce information about vending machines. I could find some results : Inner protocol in vending machine and between the PC is called MDB and is specified by NAMA. This is a…
Yahya Tawil
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