stm32 - STM32F0 Discovery USART sends the wrong value -

-

i'm making first steps in stm32 world, , quite hard. run discovery board. when learnt how control gpio , interrupts them decided play usart. , here hell began. i've spent 2 evenings struggling such simple thing serial communications!

what have:

  • configured gpio
  • configured usart
  • clock standard stm library - hsi 48 mhz
  • i see characters in putty
  • transmission parameters tested: 8n1 9600 , 115200

as can see code, i'm expecting see 'a' character while '_'. in opinion baud rate, wrong character. when change brr wrong value display junk characters.

any idea welcome!

#include <stm32f0xx.h>  void putc(uint8_t character) {   while(!(usart1->isr & usart_isr_txe))     ;    usart1->tdr = character; }  int main(void) {   int i;    rcc->apb2enr |= rcc_apb2enr_usart1en | rcc_apb2enr_syscfgcompen;   rcc->ahbenr |= (rcc_ahbenr_gpiocen | rcc_ahbenr_gpioaen);    //iosetup();   gpioa->moder &= ~(gpio_moder_moder9 | gpio_moder_moder10);   gpioa->moder |= (gpio_moder_moder9_1 | gpio_moder_moder10_1);    gpioa->ospeedr &= ~(gpio_ospeedr_ospeedr9 | gpio_ospeedr_ospeedr10);   gpioa->ospeedr |= (gpio_ospeedr_ospeedr9_0 | gpio_ospeedr_ospeedr10_0);    gpioa->pupdr &= ~(gpio_pupdr_pupdr9 | gpio_pupdr_pupdr10);   gpioa->pupdr |= gpio_pupdr_pupdr9_0 | gpio_pupdr_pupdr10_0;    gpioa->afr[1] |= (0x00000110);     // usart   usart1->brr = (uint32_t)(48000000/9600);   // 9600    //usart1->cr2 = 0;   //usart1->cr3 = 0;   //usart1->gtpr = 0;   usart1->cr1 = usart_cr1_ue | usart_cr1_te | usart_cr1_re;    (i = 0; < 0x1000; i++)     __nop();    = 0;    for(;;) {     putc('a');   }    return 0; }

hsi not precise , not stable clock. has big error related temperature , frequency in "perfect" temperature not either. if "wrong" value few percent away value calculated, can 100% problem hsi accuracy.

your choice use external crystal. if "wrong" value multiple of calculated (like 2, 4, 8 times smaller/bigger), guess should take @ code in systeminit() sets clock.


Comments

Post a Comment

Popular posts from this blog

c++ - QTextObjectInterface with Qml TextEdit (QQuickTextEdit) -

-
i registred handler simple qtextobjectinterface , draws 10x10 red rectangle. when used qtextedit in normal qwidget app, worked. when used qquicktextedit (textedit qml component) in qt quick app, doesn't worked (nothing drawed, rectangle in textedit reserved, because when change cursor position, notice there something, empty space, nothing drawed. qtextobjectinterface intrinsicsize method called (that explains why see there empty space 10x10), drawobject method isn't. i did research , found problem here: qquicktextedit.cpp qt 5.3.0 sources (line 1821) qsgnode *qquicktextedit::updatepaintnode(qsgnode *oldnode, updatepaintnodedata *updatepaintnodedata) { . . . if (textframe->firstposition() > textframe->lastposition() && textframe->frameformat().position() != qtextframeformat::inflow) { updatenodetransform(node, d->document->documentlayout()->frameboundingrect(textframe).topleft()); c...
Read more

javascript - angular ng-required radio button not toggling required off in firefox 33, OK in chrome -

-
i trying toggle required attribute on radio button using angular show html5 popup. i cannot following code function correctly in firefox 33. function correctly in chrome. required property being toggled via checkbox value, in firefox, when set false radio button still acts required , shows html5 required popup. see plnkr below example doesn't work me in ff 33. <!doctype html> <html> <head> <script data-require="angular.js@*" data-semver="1.3.1" src="//code.angularjs.org/1.3.1/angular.js"></script> <link href="style.css" rel="stylesheet" /> <script src="script.js"></script> </head> <body ng-app="myapp"> <script> angular.module('myapp',[]) .controller('mycontroller',['$scope',function($scope) { $scope.foorequired=true; $scope.submitform = function() { $scope.submitmessage = ...
Read more

xcode - Swift Playground - Files are not readable -

-
Image
files not readable in swift playground . how make files readable? same code runs on xcode terminal app, fails on swift playground. demo code below. import foundation println("hello, world!") var fname:string = "/users/holyfield/desktop/com.apple.iconcomposer.plist" var fm:nsfilemanager = nsfilemanager.defaultmanager() if(fm.fileexistsatpath(fname)){ println("file exists") if(fm.isreadablefileatpath(fname)){ println("file readable") var fd:nsdata? = nsdata(contentsoffile: fname) println(fd?.length) let pl = nsdictionary(contentsoffile: fname) println(pl?.count) println(pl?.allkeys) }else{ println("file not readable") } } else{ println("file not exists") } sample images: i have thank nate cook first quick response , solid answer. just case share answer post, title misleading. see nate's answer here: https://stackoverf...
Read more