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#include "project.h"
static volatile uint32_t hz = HZ;
static volatile uint32_t cycle_ref;
static volatile uint32_t rtc_ref;
#define RTC_IN_LH 0x21f7
#define RTC_IN_UH 0x6a6d
static EPOCH rtc_offset;
static uint16_t rtc_half;
volatile unsigned rtc_ready;
static EPOCH bkp_read_off (void)
{
EPOCH e;
uint64_t v;
v = BKP_DR1 & 0xffff;
v <<= 16;
v |= (BKP_DR2 & 0xffff);
v <<= 16;
v |= (BKP_DR3 & 0xffff);
v <<= 16;
v |= (BKP_DR4 & 0xffff);
e.s = (int64_t) v;
v = BKP_DR5 & 0xffff;
v <<= 16;
v |= (BKP_DR6 & 0xffff);
e.ns = (int64_t) v;
return e;
}
static void bkp_write_off (EPOCH e)
{
uint64_t v;
v = (uint64_t) e.s;
BKP_DR4 = (uint16_t) (v & 0xffff);
v >>= 16;
BKP_DR3 = (uint16_t) (v & 0xffff);
v >>= 16;
BKP_DR2 = (uint16_t) (v & 0xffff);
v >>= 16;
BKP_DR1 = (uint16_t) (v & 0xffff);
v = (uint64_t) e.ns;
BKP_DR6 = (uint16_t) (v & 0xffff);
v >>= 16;
BKP_DR5 = (uint16_t) (v & 0xffff);
}
void rtc_isr (void)
{
uint32_t now;
static uint32_t then;
uint32_t v;
static int warm_up = 3;
now = DWT_CYCCNT;
compiler_mb();
rtc_clear_flag (RTC_SEC);
v = rtc_get_counter_val();
// TOGGLE (LED1);
cycle_ref = now;
if (warm_up) warm_up--;
else hz = now - then;
switch (rtc_half) {
case RTC_IN_LH:
if (! (v & 0x8000000)) break;
BKP_DR7 = rtc_half = RTC_IN_UH;
break;
case RTC_IN_UH:
if (v & 0x8000000) break;
BKP_DR7 = rtc_half = RTC_IN_LH;
rtc_offset.s += 0x100000000ULL;
bkp_write_off (rtc_offset);
break;
default:
if (v & 0x8000000)
BKP_DR7 = rtc_half = RTC_IN_UH;
else
BKP_DR7 = rtc_half = RTC_IN_LH;
}
compiler_mb();
rtc_ref = v;
rtc_ready = 1;
// printf ("Ctr %d %u %u\r\n", (int) v, (int) (now - then),(unsigned) rtc_offset.s);
then = now;
}
EPOCH rtc_get (void)
{
EPOCH e, o;
uint32_t h, c, r1, r2;
uint32_t now = DWT_CYCCNT;
do {
r1 = rtc_ref;
compiler_mb();
c = cycle_ref;
h = hz;
o = rtc_offset;
compiler_mb();
r2 = rtc_ref;
} while (r1 != r2);
now -= c;
e.ns = now;
e.ns *= 1000000000ULL;
if (h) e.ns /= h;
else e.ns /= HZ;
e.s = r1;
return time_epoch_add (e, o);
}
void rtc_init (void)
{
rtc_offset = bkp_read_off();
rtc_half = BKP_DR7;
#if 1
rtc_offset.s = 1637490753 + 46850+ 48565+85980;
rtc_offset.ns = 498866999;
bkp_write_off (rtc_offset);
#endif
rtc_auto_awake (RCC_LSE, 0x7fff); //32768Hz
rtc_interrupt_enable (RTC_SEC);
nvic_enable_irq (NVIC_RTC_IRQ);
}
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