Revision as of 12:32, 6 March 2012

Preparing for programming the STM32F107VC Real Time Clock.

//Define where in the memory the RTC start address peripheral is located
#define RTC_BASE         0x40002800; // See reference manual page 52

//Define the RTC register map. See reference manual section 18.4.7 page 474
unsigned short int volatile * const rtc_crh  = (unsigned short int *) RTC_BASE + 0x0;
unsigned short int volatile * const rtc_crl  = (unsigned short int *) RTC_BASE + 0x4;
unsigned short int volatile * const rtc_prlh = (unsigned short int *) RTC_BASE + 0x8;

//Initialize the RTC peripheral. See reference manual section 18 page 463
void rtc_init(void) {
 // Your code here
}

Initializing the RTC

Goals

Enabling the RTC

One seconds TICK

No interrupts enable

Initializing second counter to present time (Epoch 1/1-1970 00:00:00)

Using external XTAL

Write protect against accidental writes

Enabling the RTC

1. To enable the RTC it is necessary to enable the Power interface in the RCC->APB1ENR register by setting the PWREN bit to 1. (Reference manual section 8.3.8 page 144)
2. To disable write protection to the Backup domain control register - enabling configuration of the RTC in the PWR->CR register setting the DBP bit to 1. (Reference manual section 5.4.1 page 75)

Links

• Const and volatile type qualifiers