{"id":1172,"date":"2022-08-24T04:15:50","date_gmt":"2022-08-24T04:15:50","guid":{"rendered":"https:\/\/blog.embeddedexpert.io\/?p=1172"},"modified":"2022-08-24T04:18:02","modified_gmt":"2022-08-24T04:18:02","slug":"hanging-core-frequency-of-stm32l053-using-registers-only","status":"publish","type":"post","link":"https:\/\/blog.embeddedexpert.io\/?p=1172","title":{"rendered":"Changing core frequency of STM32L053 using registers only"},"content":{"rendered":"\n
\"\"<\/figure><\/div>\n\n\n\n

In this guide, we shall see how to push STM32L053 to run at 32MHz rather than the default frequency of 2.096 MHz.<\/p>\n\n\n\n

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

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

1. Steps:<\/h2>\n\n\n\n

In order to push STM32L053 to maximum, we shall use external oscillator. Since the Nucleo-L053 has built-in 8Mhz generated from ST-Link, we shall use that as our oscillator. <\/p>\n\n\n\n

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

The steps are as following:<\/p>\n\n\n\n

  • Set flash latency to 1WS (waiting cycle).<\/li>
  • Bypass the HSE oscillator.<\/li>
  • Enable HSE.<\/li>
  • Disable the PLL.<\/li>
  • Configure the PLL.<\/li>
  • Enable the PLL.<\/li>
  • Select the PLL as the clock source.<\/li><\/ul>\n\n\n\n

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

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

    2. Coding:<\/h2>\n\n\n\n

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

    Create a new source and header file with name of core.c and core.h<\/p>\n\n\n\n

    Inside core.c, create a function:<\/p>\n\n\n\n

    void config_core_32mhz()\n{\n}<\/pre><\/div>\n\n\n\n
    Inside the function:<\/p>\n\n\n\n
    Set flash latency to 1WS and wait for the value to set:<\/p>\n\n\n\n
    \tFLASH->ACR |= FLASH_ACR_LATENCY; \/* (1) *\/\n\twhile (!(FLASH->ACR & FLASH_ACR_LATENCY));<\/pre><\/div>\n\n\n\n
    Bypass the HSE:<\/p>\n\n\n\n
    \tRCC->CR|=RCC_CR_HSEBYP;<\/pre><\/div>\n\n\n\n
    Enable the HSE and wait for the HSE to be ready:<\/p>\n\n\n\n
    \tRCC->CR|=RCC_CR_HSEON;\n\twhile(!(RCC->CR & RCC_CR_HSERDY));<\/pre><\/div>\n\n\n\n
    Disable the PLL and wait for the PLL to be disabled:<\/p>\n\n\n\n
    \tRCC->CR &= ~RCC_CR_PLLON; \/* (3) *\/\n\twhile ((RCC->CR & RCC_CR_PLLRDY));<\/pre><\/div>\n\n\n\n
    Set the PLL multiplication to 8, divider to 2 and source to be HSE:<\/p>\n\n\n\n
    \tRCC->CFGR |= RCC_CFGR_PLLMUL8;\n\tRCC->CFGR |= RCC_CFGR_PLLDIV2;\n\tRCC->CFGR |= RCC_CFGR_PLLSRC_HSE;<\/pre><\/div>\n\n\n\n
    Enable the PLL and wait until the PLL is ready:<\/p>\n\n\n\n
    \tRCC->CR |= RCC_CR_PLLON;\n\twhile (!(RCC->CR & RCC_CR_PLLRDY));<\/pre><\/div>\n\n\n\n
    Switch to PLL to be the source:<\/p>\n\n\n\n
    \tRCC->CFGR |= RCC_CFGR_SW_PLL;\n\twhile (!(RCC->CFGR & RCC_CFGR_SWS_PLL) );<\/pre><\/div>\n\n\n\n
    Thats it for the source file.<\/p>\n\n\n\n
    For the header:<\/p>\n\n\n\n
    #ifndef CORE_H_\n#define CORE_H_\nvoid config_core_32mhz();\n\n\n#endif \/* CORE_H_ *\/\n<\/pre><\/div>\n\n\n\n
    3. Testing Using Systick:<\/h2>\n\n\n\n
    In main.c:<\/p>\n\n\n\n
    #include "delay.h"\n#include "stm32l0xx.h"\nextern void config_core_32mhz();\nint main(void)\n{\n\tconfig_core_32mhz();\n\t__disable_irq();\n\tSysTick->LOAD=32000-1;\n\tSysTick->VAL=0;\n\tSysTick->CTRL=7;\n\t__enable_irq();\n\tRCC->IOPENR |=RCC_IOPENR_IOPAEN;\n\tGPIOA->MODER|= GPIO_MODER_MODE5_0; \/\/PA5 as output\n\tGPIOA->MODER&=~ GPIO_MODER_MODE5_1; \/\/PA5 as output\n\n\twhile(1)\n\t{\n\n\t}\n\n}\n\n\n\nvoid SysTick_Handler(void)\n{\nGPIOA->ODR^=GPIO_ODR_OD5;\n\n}\n<\/pre><\/div>\n\n\n\n
    Compile and upload the code to your mcu and using oscilloscope and probe PA5 and you should get the following:<\/p>\n\n\n\n
    \"\"<\/figure>\n\n\n\n
    Since each division of the horizontal line is 500microseconds, and we are getting 2 division high and two division low, thats mean the on time 1 millisecond and 1 millisecond off which as we set it. Thats mean we successfully changed the core frequency from 2.096MHz to 32MHz. Now, you can get the full potential of your mcu.<\/p>\n\n\n\n
    <\/p>\n\n\n\n
    Happy coding \ud83d\ude42 <\/p>\n","protected":false},"excerpt":{"rendered":"
    In this guide, we shall see how to push STM32L053 to run at 32MHz rather than the default frequency of 2.096 MHz. 1. Steps: In order to push STM32L053 to maximum, we shall use external oscillator. Since the Nucleo-L053 has built-in 8Mhz generated from ST-Link, we shall use that as our oscillator. The steps are […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,12],"tags":[],"class_list":["post-1172","post","type-post","status-publish","format-standard","hentry","category-embedded-systems","category-stm32"],"_links":{"self":[{"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=\/wp\/v2\/posts\/1172"}],"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=1172"}],"version-history":[{"count":2,"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=\/wp\/v2\/posts\/1172\/revisions"}],"predecessor-version":[{"id":1174,"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=\/wp\/v2\/posts\/1172\/revisions\/1174"}],"wp:attachment":[{"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1172"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1172"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.embeddedexpert.io\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1172"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}