uart

Cannot transmit every characters through UART

狂风中的少年 提交于 2019-11-28 12:34:41
I am using stm32f0 MCU. I would like to transmit every single byte received from the uart out of the uart. I am enabling an interrupt on every byte received from uart. My code is quite simple. uint8_t Rx_data[5]; //Interrupt callback routine void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) { if (huart->Instance == USART1) //current UART { HAL_UART_Transmit(&huart1, &Rx_data[0], 1, 100); HAL_UART_Receive_IT(&huart1, Rx_data, 1); //activate UART receive interrupt every time on receiving 1 byte } } My PC transmits ASCII 12345678 to stm32. If things work as expected, the PC should be

parsing complete messages from serial port

梦想的初衷 提交于 2019-11-28 11:49:05
I am trying to read complete messages from my GPS via serial port. The message I am looking for starts with: 0xB5 0x62 0x02 0x13 So I read from the serial port like so while (running !=0) { int n = read (fd, input_buffer, sizeof input_buffer); for (int i=0; i<BUFFER_SIZE; i++) { if (input_buffer[i]==0xB5 && input_buffer[i+1]== 0x62 && input_buffer[i+2]== 0x02 && input_buffer[i+3]== 0x13 && i<(BUFFER_SIZE-1) ) { // process the message. } } The problem I am having is that I need to get a complete message. Half of a message could be in the buffer one iteration. And the other half could come into

call to request_mem_region() fails

馋奶兔 提交于 2019-11-28 06:07:52
问题 The start address 0x4806E000 (UART4 base address) is already present in /proc/iomem with the name omap4-uart. How to disable the memory regions already allocated ?. Edit : Even though request_mem_region is successful the console during booting shows this messages. [ 0.758514] Serial: 8250/16550 driver, 3 ports, IRQ sharing enabled [ 0.760040] omap_uart.0: ttyO0 at MMIO 0x4806a000 (irq = 104) is a OMAP UART0 [ 0.760498] omap_uart.1: ttyO1 at MMIO 0x4806c000 (irq = 105) is a OMAP UART1 [ 0

Raspberry Pi UART program in C using termios receives garbage (Rx and Tx are connected directly)

守給你的承諾、 提交于 2019-11-28 05:14:58
问题 I have a simple program written in C which uses termios to send a basic string to the Raspberry Pi UART and attempts to read and output the response. The Rx and Tx pins on the Raspberry Pi are connected with a jumper so whatever is sent should be immediately received. Despite the program outputting that it successfully sent and received 5 characters for the chosen string ('Hello'), trying to print the contents of the buffer just produces one or two garbage characters. The program: #include

ArmLinux BOOTLOADER全程详解

橙三吉。 提交于 2019-11-28 03:09:25
网上关于Linux的BOOTLOADER文章不少了,但是大都是vivi,blob等比较庞大的程序,读起来不太方便,编译出的文件也比较大,而且更多的是面向开发用的引导代码,做成产品时还要裁减,这一定程度影响了开发速度,对初学者学习开销也比较大,在此分析一种简单的BOOTLOADER,是在三星公司提供的2410 BOOTLOADER上稍微修改后的结果,编译出来的文件大小不超过4k,希望对大家有所帮助. 1.几个重要的概念 COMPRESSED KERNEL and DECOMPRESSED KERNEL 压缩后的KERNEL,按照文档资料,现在不提倡使用DECOMPRESSED KERNEL,而要使用COMPRESSED KERNEL,它包括了解压器.因此要在ram分配时给压缩和解压的KERNEL提供足够空间,这样它们不会相互覆盖.当执行指令跳转到 COMPRESSED KERNEL后,解压器就开始工作,如果解压器探测到解压的代码会覆盖掉COMPRESSED KERNEL,那它会直接跳到COMPRESSED KERNEL后存放数据,并且重新定位KERNEL,所以如果没有足够空间,就会出错. Jffs2 File System 可以使armlinux应用中产生的数据保存在FLASH上,我的板子还没用到这个. RAMDISK 使用RAMDISK可以使ROOT FILE

基于FPGA/CPLD设计与实现UART

ⅰ亾dé卋堺 提交于 2019-11-28 02:38:10
http://hi.baidu.com/hieda/blog/item/750eac88fcf5d790a5c2727e.html - 基于FPGA/CPLD设计与实现UART -- 摘 要:UART是广泛使用的串行数据通讯电路。本设计包含UART发送器、接收器和波特率发生器。设计应用EDA技术,基于FPGA/CPLD器件设计与实现UART。 关键词:FPGA/CPLD;UART;VHDL UART(即Universal Asynchronous Receiver Transmitter 通用异步收发器)是广泛使用的串行数据传输协议。UART允许在串行链路上进行全双工的通信。 --- 串行外设用到RS232-C异步串行接口,一般采用专用的集成电路即UART实现。如8250、8251、NS16450等芯片都是常见的UART器件,这类芯片已经相当复杂,有的含有许多辅助的模块(如FIFO),有时我们不需要使用完整的UART的功能和这些辅助功能。或者设计上用到了FPGA/CPLD器件,那么我们就可以将所需要的UART功能集成到FPGA内部。使用VHDL将UART的核心功能集成,从而使整个设计更加紧凑、稳定且可靠。本文应用EDA技术,基于FPGA/CPLD器件设计与实现UART。 一 UART简介 1 UART结构 --- UART主要有由数据总线接口、控制逻辑、波特率发生器

Difference between device_register and driver_register

懵懂的女人 提交于 2019-11-28 02:04:58
问题 I am writing a UART driver. I came across the two functions in the chapter 14.Linux Device Model. int device_register(struct device *dev); int driver_register(struct device_driver *drv); Since UART is a char driver I have dynamically created the major number using ( alloc_chrdev_region) and added the device to kernel by using cdevadd() . I came across uart_register_driver() and platform_driver_register() in omap-serial.c. I could map the driver_register with the platform_driver_register() but

Pymodbus - Read input register of Energy meter over rs485 on uart of raspberry pi3

主宰稳场 提交于 2019-11-28 01:45:23
I have one energy meter and i am trying to retrieve voltage, freq values from meter on raspberry pi uart over RS485 My connections for raspberry pi and rs485 are as follows Rs485 DI - Tx of raspberry pi Rs485 R0 - Rx of raspberry pi Rs485 DE/RE -Pin 7 of raspberry pi my code is as follows: import serial import RPi.GPIO as GPIO from pymodbus.client.sync import ModbusSerialClient as ModbusClient from pymodbus.register_read_message import ReadInputRegistersResponse from pymodbus.register_read_message import ReadInputRegistersRequest import logging logging.basicConfig() log = logging.getLogger()

stm32中阻塞模式和非阻塞模式 in blocking mode 与 in non-blocking mode区别

扶醉桌前 提交于 2019-11-27 21:05:35
阻塞模式和非阻塞模式...... 我的理解是: 阻塞模式就像是一个延时函数,当这个函数没处理完那么,所有的按照流程需要执行的代码都不会被执行,要等到这个延时完成,类似 平时看书上写的LED灯闪烁,用的delay()一样.. 而非阻塞模式就像他定义的那样,一般用的是中断,执行这条语句的时候,开启相应的中断达到一定的条件才进行处理,这样不会影响到流程的执行. 我的理解就是,阻塞就是死等,非阻塞就是中断 可以参考 /** * @brief Sends an amount of data in non blocking mode. * @note When UART parity is not enabled (PCE = 0), and Word Length is configured to 9 bits (M1-M0 = 01), * the sent data is handled as a set of u16. In this case, Size must indicate the number * of u16 provided through pData. * @param huart Pointer to a UART_HandleTypeDef structure that contains * the configuration information for

树莓派485串口访问不稳定的问题,搞了两天

放肆的年华 提交于 2019-11-27 19:33:23
换了块树莓派的主板,忘了设置串口,导致读取结果时有时无,有时乱码,有时无数据,后来检查配置才发现,记录一下开启Uart接口方法 sudo raspi - config 选择 Interfacing Options -> Serial ,关闭 shell 访问,打开硬件串口 打开/boot/config.txt文件,找到如下配置语句使能串口,如果没有,可添加在文件最后面。 enable_uart = 1 对于树莓派3B用户,串口用于蓝牙,需要注释掉: #dtoverlay=pi3-miniuart-bt 然后重启树莓派,再测试正常。 来源: https://www.cnblogs.com/qq812256/p/11374385.html