uart | 易学教程

Enabling UART on Beaglebone Black

阅读更多关于 Enabling UART on Beaglebone Black

问题 I'm having trouble getting UART enabled. I've gone through many different directions on how to enable and troubleshoot from updating the uEnv.txt file to updating the kernel. I've come to conclude that it may be an issue with using a different kernel than the instructions, but I'm not sure? I don't know very much about the Beaglebone and I'm still learning. Whenever I try to test UART by using Python and typing the following: import Adafruit_BBIO.UART as UART UART.setup("UART1") I get the

USB、UART、SPI等总线速率(转)

阅读更多关于 USB、UART、SPI等总线速率(转)

1. USB总线 USB1.1： ——-低速模式(low speed)：1.5Mbps ——-全速模式(full speed)： 12Mbps USB2.0：向下兼容。增加了高速模式，最大速率480Mbps。 ——-高速模式(high speed)： 25~480Mbps USB3.0：向下兼容。 ——-super speed ：理论上最高达4.8Gbps，实际中，也就是high speed 的10倍左右。 2. UART RS232：传输速率一般不超过20Kbps，速率低，抗干扰能力差，RS-232C能传输的最大距离不超过15m（50英尺）。 RS422：定义了一种平衡通信接口，将传输速率提高到10Mbps，传输距离延长到4000英尺（速率低于100Kbps时），并允许在一条平衡总线上连接最多10个接收器。RS-422是一种单机发送、多机接收的单向、平衡传输规范，被命名为TIA/EIA-422-A标准。 RS485：增加了多点、双向通信能力，即允许多个发送器连接到同一条总线上，同时增加了发送器的驱动能力和冲突保护特性，扩展了总线共模范围，后命名为TIA/EIA-485-A标准。最高传输速率10Mbps，抗干扰能力强，可以传距离1.5km。平衡双绞线的长度与传输速率成反比，在100Kbps速率以下，才可能使用规定最长的电缆长度。只有在很短的距离下才能获得最高速率传输

ARM Assembly Language uART0 Input Output, What am I doing wrong.

阅读更多关于 ARM Assembly Language uART0 Input Output, What am I doing wrong.

问题 Write two (2) ARM assembly language subroutines, called output_char and read_char. These subroutines will allow a user to enter a character and display the character in PuTTy via the UART. All user input should be echoed back to the display I tried writing the code but it did not work. U0LSR EQU 0x14 register EQU 0xE000C000 STMFD SP!,{lr} read_character LDR r0, =0xE000C014 LDRB r1, [r0] BIC r1, r1, #0xFFFFFFFE CMP r1, #0 BEQ read_character LDR r6, =register LDR r2, [r6] output_character LDR

Loop back mode enabling?

阅读更多关于 Loop back mode enabling?

问题 I want the software loop back to be tested using my application code for uart4 instance of omap-4460.I am using the default driver. How will I do it using ioctl?or any other way. Please find the driver code here omap-serial.c. Please share any reference code. 来源： https://stackoverflow.com/questions/23243494/loop-back-mode-enabling

Uart / GPS driver sample buffer overflow

阅读更多关于 Uart / GPS driver sample buffer overflow

问题 I am trying the sample for the GPS driver with a raspberry pi 3 and the Ultimate GPS V3 breakout board. Here is the full source code: https://github.com/androidthings/drivers-samples/tree/master/gps The GPS board is connected following this schematics: When launching the sample app, I get the following error: com.example.androidthings.driversamples E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.androidthings.driversamples, PID: 1299 java.nio.BufferOverflowException at java.nio

PySerial write errors (baudrate sensitive)

阅读更多关于 PySerial write errors (baudrate sensitive)

问题 I'm having some issues with pyserial and windows (on linux it works fine with the same code); I seem to be writing erroneous bytes. The code even works fine on the same machine inside a debian VM, So Im pretty sure its a software thing. I'm using Python 2.7.6 32bit, pyserial 2.7 but have tried others (2.5 and 2.4) all exibit the same errors. Interestingly enough, the errors are much less frequent when the baudrate is increased to 115200. This is the relavant bit of my code: ser = serial

Linux, termios: how to handle negative result of select()

阅读更多关于 Linux, termios: how to handle negative result of select()

问题 I'm developing on an am335x system with ubuntu and the last kernel released from TI (vendor). I'm using a virtual tty device (ttyUSB0) for comunicate with a remote device. After about one hour of continuous comunication (cyclic open-transmit-receive-close) I get a strange behaviour of read(). If the UART is opened in blocking mode the read hangs forever (no matter what value I set on VMIN&VTIME). If I open it in non-blocking mode it return -1 for ever (after 1 hour). Now I'm using select() to

i have enabled the Uart in linux source and created a image how to test the uart working

阅读更多关于 i have enabled the Uart in linux source and created a image how to test the uart working

问题 hi I am newbie please help me i have enabled the Uart in linux source and created a image,and while kernel boot time its showing me the log Serial: 8250/16550 driver, 5 ports, IRQ sharing disabled serial8250.0: ttyS0 at MMIO 0x4000c000 (irq = 5) is a 16550A console [ttyS0] enabled serial8250.2: ttyS1 at MMIO 0x40098000 (irq = 7) is a 16550A serial8250.3: ttyS2 at MMIO 0x4009c000 (irq = 8) is a 16550A and ttyS0 is used for interaction between host terminal and my target board that is working

Virtual Com-Port communication through Matlab

阅读更多关于 Virtual Com-Port communication through Matlab

问题 While connecting my Com-port using matlab, many a times(4 out of 5) I get an error ??? Error using ==> serial.fopen at 72 Port: COM21 is not available. Available ports: COM3, COM10, COM17, COM18. However , sometimes it gets connected and responds as expected. Can anyone tell me whats the problem with this? By the way , I am using this snippet to connect my microcontroller to PC through USB s = serial('COM21'); // code to initialize the req COM i.e. COM21 for me fopen(s); 回答1: I ran into this

Using Serial Peripheral Interface (SPI) to talk to several slaves simultaneously

阅读更多关于 Using Serial Peripheral Interface (SPI) to talk to several slaves simultaneously

问题 I have four Atmega328p in a single board and I want one of them send the same data (i.e. sensor readings) to the other three simultaneously. I'm not interested in a bidirectional communication. I read this thread (How can I broadcast data to multiple SPI slaves and how it works?) about SPI broadcasting, and someone mentioned not being possible because in SPI communication is full duplex and MISO and MOSI lines are active at the same time. However, I was wondering if I could just let the MISO