Check RTC LSE(External Xtal, 32.768kHz) mode
Please refer follow links.
My notebook
http://developer.mbed.org/users/kenjiArai/notebook/nucleo-series-clock-structure-and-xtal-oscillation/
Q&A for RTC Xtal
http://developer.mbed.org/questions/4531/RTC-External-Crystal-Nucleo/
main.cpp
- Committer:
- kenjiArai
- Date:
- 2014-10-25
- Revision:
- 1:eaa3c3f36c03
- Parent:
- 0:bad75bd13618
- Child:
- 2:8b6a8cfa173a
File content as of revision 1:eaa3c3f36c03:
/* * mbed Application program * RTC Clock test * * Copyright (c) 2010-2014 Kenji Arai / JH1PJL * http://www.page.sannet.ne.jp/kenjia/index.html * http://mbed.org/users/kenjiArai/ * Created: October 24th, 2014 * Revised: October 25th, 2014 * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ // Include --------------------------------------------------------------------------------------- #include "mbed.h" #include "rtc_api.h" // Definition ------------------------------------------------------------------------------------ #define STANDARD_FUNCTION // Use standard library prepared by STMicroelectronics //#define SPECIAL_FUNCTION // Use special function. Time out is much longer than standard function #define BAUD(x) pc.baud(x) #define GETC(x) pc.getc(x) #define PUTC(x) pc.putc(x) #define PRINTF(...) pc.printf(__VA_ARGS__) #define READABLE(x) pc.readable(x) #define TIMEOUT ((uint32_t)5000) // Object ---------------------------------------------------------------------------------------- Serial pc(USBTX, USBRX); DigitalOut myled(LED1); Timer t; // RAM ------------------------------------------------------------------------------------------- // ROM / Constant data --------------------------------------------------------------------------- // Function prototypes --------------------------------------------------------------------------- uint32_t Set_RTC_LSI(void); void rtc_external_osc_init(void); uint32_t Set_RTC_LSE(void); //------------------------------------------------------------------------------------------------- // Control Program //------------------------------------------------------------------------------------------------- int main() { while(true) { PRINTF("Select RTC clock source\r\n"); t.reset(); t.start(); #if defined(STANDARD_FUNCTION) rtc_init(); t.stop(); PRINTF("Use standard function by STM\r\n"); PRINTF("The time taken was %f sec. (Time-out setting:%f sec.)\r\n", t.read(), (float)LSE_TIMEOUT_VALUE/1000); #elif defined(SPECIAL_FUNCTION) rtc_external_osc_init(); t.stop(); PRINTF("Use special function (extend time-out)\r\n"); PRINTF("The time taken was %f sec. (Time-out setting:%f sec.)\r\n", t.read(), (float)(float)TIMEOUT/1000); #endif switch ((RCC->BDCR >> 8) & 0x03) { case 0: // no clock PRINTF("No clock"); break; case 1: // LSE PRINTF("Use LSE"); break; case 2: // LSI PRINTF("Use LSI"); break; case 3: // HSE PRINTF("Use HSE"); break; default: // Not come here PRINTF("?"); break; } PRINTF("\r\n"); Set_RTC_LSI(); if (((RCC->BDCR >> 8) & 0x03) != 2) { PRINTF("Please remove USB then re-plug again"); } else { PRINTF("Use LSI again", (float)TIMEOUT/1000); } PRINTF("\r\nRepeat again? [y/n]\r\n"); PRINTF(" If yes, please pusch [RESET] buttom.\r\n If no, please hit any key.\r\n"); if (GETC()){ break; } } PRINTF("next\r\n"); #if defined(STANDARD_FUNCTION) rtc_init(); #elif defined(SPECIAL_FUNCTION) rtc_external_osc_init(); #endif } uint32_t Set_RTC_LSE(void) { uint32_t timeout = 0; //---------------------------- LSE Configuration ------------------------- // Enable Power Clock __PWR_CLK_ENABLE(); // Enable write access to Backup domain PWR->CR |= PWR_CR_DBP; // Wait for Backup domain Write protection disable timeout = HAL_GetTick() + DBP_TIMEOUT_VALUE; while((PWR->CR & PWR_CR_DBP) == RESET){ if(HAL_GetTick() >= timeout){ return 0; } } // Reset LSEON and LSEBYP bits before configuring the LSE ---------------- __HAL_RCC_LSE_CONFIG(RCC_LSE_OFF); // Get timeout timeout = HAL_GetTick() + ((uint32_t)5000); // Wait till LSE is ready while(__HAL_RCC_GET_FLAG(RCC_FLAG_LSERDY) != RESET){ if(HAL_GetTick() >= timeout) { return 0; } } // Set the new LSE configuration ----------------------------------------- __HAL_RCC_LSE_CONFIG(RCC_LSE_ON); // Get timeout timeout = HAL_GetTick() + ((uint32_t)5000); // Wait till LSE is ready while(__HAL_RCC_GET_FLAG(RCC_FLAG_LSERDY) == RESET){ if(HAL_GetTick() >= timeout){ return 0; } } return 1; } void rtc_external_osc_init(void) { // Enable Power clock __PWR_CLK_ENABLE(); // Enable access to Backup domain HAL_PWR_EnableBkUpAccess(); // Reset Backup domain __HAL_RCC_BACKUPRESET_FORCE(); __HAL_RCC_BACKUPRESET_RELEASE(); // Enable LSE Oscillator if (Set_RTC_LSE()) { // Connect LSE to RTC __HAL_RCC_RTC_CLKPRESCALER(RCC_RTCCLKSOURCE_LSE); __HAL_RCC_RTC_CONFIG(RCC_RTCCLKSOURCE_LSE); } } uint32_t Set_RTC_LSI(void) { uint32_t timeout = 0; // Enable Power clock __PWR_CLK_ENABLE(); // Enable access to Backup domain HAL_PWR_EnableBkUpAccess(); // Reset Backup domain __HAL_RCC_BACKUPRESET_FORCE(); __HAL_RCC_BACKUPRESET_RELEASE(); // Enable Power Clock __PWR_CLK_ENABLE(); // Enable write access to Backup domain PWR->CR |= PWR_CR_DBP; // Wait for Backup domain Write protection disable timeout = HAL_GetTick() + DBP_TIMEOUT_VALUE; while((PWR->CR & PWR_CR_DBP) == RESET) { if(HAL_GetTick() >= timeout) { return 0; } } __HAL_RCC_LSE_CONFIG(RCC_LSE_OFF); // Enable LSI __HAL_RCC_LSI_ENABLE(); timeout = HAL_GetTick() + TIMEOUT; // Wait till LSI is ready while(__HAL_RCC_GET_FLAG(RCC_FLAG_LSIRDY) == RESET) { if(HAL_GetTick() >= timeout) { return 0; } } // Connect LSI to RTC __HAL_RCC_RTC_CLKPRESCALER(RCC_RTCCLKSOURCE_LSI); __HAL_RCC_RTC_CONFIG(RCC_RTCCLKSOURCE_LSI); return 1; }