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Questions tagged [uart]

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

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Xbee Router in API mode not sending frames from UART input?

My current system is setup as follows: MCU ------ Xbee A(Router) ------ Xbee B(Coordinator) Xbee A is a router in API mode, Xbee B is a coordinator in API mode. MCU is MSP430, Xbee modules are ZB ...
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55 views

Distance between UART and I2C bus

I create a board with two bus: UART and I2C. Now I am expanding the connection terminal, which has the following contacts: RX / TX / SDA / SCL / + 5V / GND. The question is, do the I2C and UART buses ...
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34 views

What if we disconnect Tx and Rx at the time of code execution in UART?

I have interfaced Nodemcu and arduino using UART communication protocol. After uploading the code, When the output is seen on serial monitor,I disconneted Tx and Rx physically. still I can see the ...
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1answer
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Issue with timer_func() and delay_func() in generic library for R551 Fingerprint Sensor - ATMega328p

Apologies for the long-winded question. I've recently stepped outside of the Arduino realm for hardware programming. I'm working on a project that interfaces a R551 Fingerprint Sensor with an ...
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2answers
62 views

How to choose UART maximum output speed?

When I open up a project in STM32CubeMX and configure a UART, there's a Maximum output speed configuration (under GPIO Settings) that defaults to Very High. The options are: Low Medium High Very High ...
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63 views

RS485 PCB Design

I'm currently in the process of designing PCBs for my project. There's going to be one larger control board, and 10 daughter boards. The daughter boards will measure the current/voltage of some ...
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1answer
37 views

Level Matching Circuit

Somebody know what do this circuit exactly or how it works ? Where VDD = 5V (MCU) and VDD_1V8 = 1V8 It is a recommended circuit to use uart communication when the voltage level are not the same, I ...
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40 views

Add CAN, UART and USB support to NUCLEO-H743ZI [closed]

I need to add CAN, UART and USB support to NUCLEO-H743ZI development board. What solutions could be recommended (besides the development of my own development board)? Update: the question is about ...
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50 views

STM32F02 Nucelo USART Erratic Behavior [on hold]

I have a project that currently has a blinky, 2 ADC channel on DMA circular which were successfully working . I have now implemented the USART2 on IRQ on my STM32F302 Nucleo. The USART2 is running at ...
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38 views

Multiple sensors on a single serial port [duplicate]

I want to use a single serial UART port on an mcu to communicate with two different sensors. I have connected both the sensors' TX lines together to mcu's RX line and vice versa. I am switching the ...
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1answer
33 views

How to avoid duplicate messages in a mesh network of mcus

I'm working on a project, where each pcb has a connector on every side, so you can connect these board in a grid. It's basically a mesh network of modules. These modules need to communicate with each ...
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39 views

Reduce wake-up noise on ARM CM3

I need some help exploring a solution. I have an ARM Cortex M3 MCU, which has low-power sleep mode implemented. Wake-up sources are any GPIO pin, or an RTC alarm. A terminal is connected to UART-0 ...
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1answer
60 views

STM32 skips UART frames after framing error

I am currently developing a DMX512 receiver with an STM32F767ZI. DMX512 is basically a protocol transmitting a byte array via RS485. In summary it works like this: > 92us low signal (called break) > ...
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Smart Charger (Tenergy TB-6AC) UART/USB interface

I have an old smart charger (Tenergy TB-6AC) which boasts the ability to interface with my computer. Upon further research, I have found that the software is no longer supported and no where to be ...
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2answers
76 views

How to design an STM32 board with UART over a USB connection?

Sorry if this seems a stupid question but I'm designing a custom PCB based on the STM32F303RE microcontroller and am slightly confused as to how the UART should be connected in the hardware in order ...
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1answer
78 views

Implementing Modbus RTU on a UART device

I have a particle counter HPMA115S0 which has a UART communication interface. I bought a TTL UART to RS485 Converter Module to make it work with a PLC over Modbus RTU protocol. I usually work with ...
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2answers
48 views

Preventing overvoltage on serial pin

I am trying to send data through serial from a 3.3v Arduino to a 5v Arduino. I assume I can't just connect the 3.3v tx to the 5v rx because, when I program the 5v one I am assuming it will send 5v ...
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2answers
65 views

How to connect multiple devices to UART bus? [closed]

I want to use a UART bus (RX-TX-GND) to communicate between one master and multiple slaves. NUCLEO-F401RE board is the bus master. B-L072Z-LRWAN1 and ESP32 are the slaves. Communication over UART ...
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1answer
92 views

Multiplexing UART TX/RX line

I need to connect UART devices in a master to multiple slaves configuration. I need to isolate the desired slave while I'm transmitting, so others will not receive, non-selected slaves must have its ...
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1answer
36 views

Data transmission from bluetooth module to fpga

I am using an android app which is taking a string and converting it to its ascii values and sending it to bluetooth module hc-05. Now i need to send this data to an UART receiver in an fpga. In what ...
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68 views

How can I estimate the minimum baudrate for a given bitrate?

My circuit performs data acquisition at 250 samples/s, 24 bits/sample and transmit this information to the local host (PC) through a bluetooth module that implements the UART protocol. As far as I ...
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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 ...
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1answer
49 views

Implementing UART flow control in microcontroller

I'm communicating data from my microcontroller (Teensy) to my Bluetooth module (nRFx) which is also a microcontroller that I can program. I use UART to communicate the data I want to send over ...
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2answers
160 views

How to configure DMA to receive variable length USART messages?

I am trying to receive USART messages on a microcontroller originating from PC which will command it to execute certain tests. I am using STM32F4, I chose to use DMA as messages on the same USART ...
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1answer
74 views

Weird character from UART. STM32L100RC

I'm having problems communicating with UART on my STM32L100RC discovery board. I get character such as xþ when I'm sending the letter 'F'. I'm using Hercule to receive data. Hercule's configuration is ...
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1answer
107 views

Why use UART to communicate between Arduino and ESP Wi-Fi module?

I have been learning about the different communication protocols used between Arduino and other components/sensors, namely, SPI, UART and I2C. I want to add Wi-Fi to my Arduino UNO project using ...
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2answers
67 views

Component recognition from marking code

I need help to recognize a dead component from a lab instrument control board. It is part of a TTL-serial interface, arguably a logic gate or some level shifter, in a TSSOP-14 package. You can see ...
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2answers
77 views

UART Issue - Communication stops working when board reset button is pressed

I am using a NUCLEO-F401RE board as a master and a B-L072CZ-LRWAN1 as a slave communicating over UART. Slave is configured to receive in interrupt mode using HAL_UART_Receive_IT. Master is programmed ...
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1answer
76 views

ESP-WROOM-32 layout USB-UART

I want my layout will include female headers to connect CP2102 MICRO USB to UART TTL Module 6Pin so I could just 'stick' it to my PCB while uploading the code. The 5V for the ESP will be supply from ...
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1answer
44 views

J1708 (open collector RS485) at higher baud rates than 9600 bps?

I have here a PCB which has a kind of "open collector" RS-485, known as J1708 (schematic attached). The default baud rate is 9600 bps and there is no terminators, J1708-TX is a 3.3V signal. I would ...
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137 views

STM32 USART synchronous mode receive does not work

I am using a STM32L052K6U6 to communicate with an SPI slave using the UART1 synchronous mode (configured with CubeMX, using the LL library). Setup code generated by CubeMX (I left out the Tx and Clk ...
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1answer
34 views

RE: Receiver Output Enable and DE: Driver Output Enable pins

Hello I am planning to use LT1785 UART-RS484 transceiver. I will use that chip in order to get RS485 data and convert it to UART signal. So I have read the datasheet but I couldn't be sure. It says ...
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1answer
68 views

GSM Modem Transmission Issue

I'm having a problem getting this GSM modem to work with an FPGA (Spartan 3). I've already implemented UART transmission on the FPGA side,the MAX232 to convert TTL->RS232, and 3.3V->5V logic level ...
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2answers
73 views

Rs485 to UART convension

I need to send data from one PIC to another PIC by using RS485. As a protocol I use UART. However, I cannot be sure about RS485 transceiver and its circuit. I will be able to supply 5 V and according ...
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1answer
31 views

How can i use HTU21D-F sensor with SC16IS750 breakout board? [closed]

i have a HTU21D-F humidity and temperature sensor. I want to take data from this sensor on I2C and transformed to UART with SC16IS750 breakout board. And i want to see this signal on an oscilloscope. ...
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148 views

How to asynchronously receive USART data using STM32 HAL?

I'm trying to accumulate any bytes that come into the UART peripheral at any moment into a circular buffer. I want to match proprietary protocol packets on this window of data, but it's unclear how I ...
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1answer
60 views

UART TO RS-232 convension

I am working on a project and I use several PIC18F26K83's for this project. For communication between PIC's I use UART. Now I also need to send data with RS232 to the user. As I have understood the ...
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35 views

Concurrent DMA streams handling UART

I've currently got a STM32F777VI microcontroller working with UART receive working through DMA. The problem starts when I try to receive data from 2 UART peripherals using DMA. According to the ...
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2answers
111 views

Garbage data when using UART on atmega2560

(updates at bottom) I am using an Arduino Mega with the SoftwareSerialExample sketch on it to send and receive bytes through UART on my ATmega2560 (which is actually on a Arduino Mega Board). ...
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1answer
112 views

How do USB to serial adapters work?

I'd like to know how a USB to serial adapter (such as the FTDI FT232RL chip) works. The way I think it does is the following: Picture a system composed of a MCU, a USB to serial adapter and the PC ...
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5answers
3k views

UART pins to unpowered MCU?

I'm using a USB-UART IC with an MCU, which is powered from a battery. The USB-UART IC is powered from USB connector, not from the battery, so that I don't need to open up a console every time when ...
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1answer
63 views

Can I use the same serial1 port to communicate with two modules?

My MCU is STM32L432KC, it has two serial ports 1 and 2. But I’m wondering if I can use the same serial port1 only to communicate with two modules (not on the same Tx & Rx pins but 4 different pins ...
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1answer
36 views

When to monitor UxSTAbits.TRMT and UxSTAbits.UTXBF

According to the reference manual on UART for PIC here(page 7), the UxSTA register have two read-only bits; TRMT and UTXBF. While writing a simple transmission program over UART, I didn't notice any ...
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1answer
61 views

Linux Drivers for FT232R [closed]

Background I am trying to build a USB Bridge circuit as part of a larger project. What I mean by that is, I wish to control a parallel out circuit based on information transmitted by the host ...
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1answer
54 views

Baud rate for Square Wave data signal via UART if frequency is given

I was trying to solve the 2013 paper set by ISRO for electrical engineers. Question no 13 made me confused. So since Idle in UART is usually high and start bit is low, we can find the 8 bit data ...
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58 views

Number of bits relation to data UART

Regarding the number of bits that is sent using UART and configuring the UART handle is unclear as well as setting the parity bit, is it odd or even. "...
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1answer
618 views

RS-485 using USART or UART port on STM32

On STM32F405 MCUs there are USART ports as well as UART ports available. If I need to implement RS-485 communication then which one of these should be used, USART or UART? Or are both of them equally ...
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1answer
114 views

Using Character Match functionality in a STM32F7 chip

I'm trying to implement a UART receiver that works by finding a '\0' in the datastream, OR when it receives 256 characters at which point the data should be processed by an interrupt. The point is to ...
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1answer
65 views

Can STM32F4 USART be used as UART?

There are 4/2 USART/UART ports in STM32F407 (Page 15) MCUs as shown in the image. I need 4 UART ports in an application. I wonder if its possible to use 2+2 (UASRT+UART) ports for my purpose in this ...
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1answer
77 views

Repurposing FT232 UART pins as parallel out

Background I am trying to build a USB Bridge circuit as part of a larger project. What I mean by that is, I wish to control a parallel out circuit based on information transmitted by the host ...