{"id":341,"date":"2021-08-19T05:04:41","date_gmt":"2021-08-19T05:04:41","guid":{"rendered":"https:\/\/blog.embeddedexpert.io\/?p=341"},"modified":"2021-09-13T04:12:42","modified_gmt":"2021-09-13T04:12:42","slug":"working-with-stm32-and-uart-part-2-sending-strings-and-variable-polling-mode","status":"publish","type":"post","link":"https:\/\/blog.embeddedexpert.io\/?p=341","title":{"rendered":"Working with STM32 and UART part 2: Sending strings and variable polling mode"},"content":{"rendered":"\n

In previous guide(part 1<\/a>), we looked for how to send a single character. Now we will extend the usage of uart module to send a string contains “Hello from stm32f4” and a variable as “my variable is variable”<\/p>\n\n\n\n

\"\"
UART<\/figcaption><\/figure><\/div>\n\n\n\n

In this guide we will cover the following:<\/p>\n\n\n\n

  • Extra steps needed to send a string<\/li>
  • Code<\/li>
  • Results<\/li><\/ul>\n\n\n\n

    1. Extra steps needed to send a string <\/h2>\n\n\n\n

    <\/p>\n\n\n\n

    Starting from part 1, we need to add the following two header file<\/p>\n\n\n\n

    #include "stdio.h" \/\/stdio which allows us to use sprinttf \n#include "stdint.h" \/\/standardd int defention <\/pre><\/div>\n\n\n\n
    then the prototype of the function to send a string <\/p>\n\n\n\n
    void UART_Write_String(char *p);<\/pre><\/div>\n\n\n\n
    then the buffer to hold the data and variable <\/p>\n\n\n\n
    char buffer[40]={'0'};\nunsigned int variable;<\/pre><\/div>\n\n\n\n
    Now for the function that allows us to print the string<\/p>\n\n\n\n
    void UART_Write_String(char *p)\n\t{\n\twhile(*p!='\\0')\n{\nUSART_write(*p);\np++;\n}\n}<\/pre><\/div>\n\n\n\n
    The function works as following<\/p>\n\n\n\n
    First, we pass the string as argument, then it sends the string character by character until reaches NULL (‘\\0’) then it stops<\/p>\n\n\n\n
    2. Code<\/h2>\n\n\n\n
    #include "stm32f4xx.h"                  \/\/ Device header\n#include "stdio.h"\n#include "stdint.h"\nvoid USART_write(int ch);\nvoid USART2_Init(void);\nvoid delay(int delayms);\nvoid UART_Write_String(char *p);\n\nchar buffer[40]={'0'};\nunsigned int variable;\n\nint main(){\n\nUSART2_Init();\nwhile(1){\nUART_Write_String("---------------------------\\r\\n");\nUART_Write_String("hello from stm32f411RE\\r\\n");\nsprintf(buffer,"my variable is %u \\r\\n",++variable);\nUART_Write_String(buffer);\nUART_Write_String("---------------------------\\r\\n");\n\/\/variable=variable+1;\ndelay(1000);\n}\n}\n\nvoid USART2_Init(void){\nRCC->APB1ENR|=RCC_APB1ENR_USART2EN;\nRCC->AHB1ENR|=RCC_AHB1ENR_GPIOAEN;\nGPIOA->AFR[0]=0x0700;\nGPIOA->MODER|=(1<<5);\/\/set bit5\nGPIOA->MODER&=~(1<<4);\/\/reset bit4\nUSART2->BRR  = 0x0681;    \/\/9600 @16MHz\nUSART2->CR1  |=0x2008; \/\/ enable tx\n\n}\n\nvoid USART_write(int ch){\nwhile(!(USART2->SR&0x0080)){\n}\nUSART2->DR=(ch);\n\t\n}\n\nvoid UART_Write_String(char *p)\n\t{\n\twhile(*p!='\\0')\n{\nUSART_write(*p);\np++;\n}\n}\n\n\nvoid delay(int delayms){\nvolatile int i;\n\tfor(; delayms>0;delayms--){\n\tfor(i=0;i<3192;i++);\n\t}\n}\n<\/pre><\/div>\n\n\n\n
    3. Results<\/h2>\n\n\n\n
    After compiling and uploading the code, open your serial terminal and set the baud to 9600 and you will get this<\/p>\n\n\n\n
    \"\"<\/figure><\/div>\n","protected":false},"excerpt":{"rendered":"
    In previous guide(part 1), we looked for how to send a single character. Now we will extend the usage of uart module to send a string contains “Hello from stm32f4” and a variable as “my variable is variable” In this guide we will cover the following: Extra steps needed to send a string Code Results […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,11,12],"tags":[],"class_list":["post-341","post","type-post","status-publish","format-standard","hentry","category-embedded-systems","category-peripheral-drivers","category-stm32"],"_links":{"self":[{"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=\/wp\/v2\/posts\/341"}],"collection":[{"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=341"}],"version-history":[{"count":2,"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=\/wp\/v2\/posts\/341\/revisions"}],"predecessor-version":[{"id":408,"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=\/wp\/v2\/posts\/341\/revisions\/408"}],"wp:attachment":[{"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=341"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=341"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=341"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}