stm: Add RTC start-up info, and uPy bindings.

stm/main.c

@@ -430,7 +430,8 @@ soft_reset:
 #endif
         rt_store_attr(m, MP_QSTR_hid, rt_make_function_n(1, pyb_hid_send_report));
 #if MICROPY_HW_ENABLE_RTC
-        rt_store_attr(m, MP_QSTR_time, rt_make_function_n(0, pyb_rtc_read));
+        rt_store_attr(m, MP_QSTR_time, (mp_obj_t)&pyb_rtc_read_obj);
+        rt_store_attr(m, qstr_from_str("rtc_info"), (mp_obj_t)&pyb_rtc_info_obj);
 #endif
 #if MICROPY_HW_ENABLE_RNG
         rt_store_attr(m, MP_QSTR_rand, rt_make_function_n(0, pyb_rng_get));

stm/rtc.c

@@ -5,38 +5,50 @@
 #include "mpconfig.h"
 #include "qstr.h"
 #include "obj.h"
+#include "systick.h"
 #include "rtc.h"
 
+machine_uint_t rtc_info;
+
+#define RTC_INFO_USE_EXISTING (0)
+#define RTC_INFO_USE_LSE (1)
+#define RTC_INFO_USE_LSI (3)
+
 void rtc_init(void) {
-    /* Enable the PWR clock */
+    // Enable the PWR clock
     RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);
 
-    /* Allow access to RTC */
+    // Allow access to RTC
     PWR_BackupAccessCmd(ENABLE);
 
     if (RTC_ReadBackupRegister(RTC_BKP_DR0) == 0x32F2) {
         // RTC still alive, so don't re-init it
         // wait for RTC APB register synchronisation
         RTC_WaitForSynchro();
+        rtc_info = RTC_INFO_USE_EXISTING;
         return;
     }
 
     uint32_t timeout = 10000000;
 
-    /* Enable the PWR clock */
+    // Enable the PWR clock
     RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);
 
-    /* Allow access to RTC */
+    // Allow access to RTC
     PWR_BackupAccessCmd(ENABLE);
 
-    /* Enable the LSE OSC */
+    // Enable the LSE OSC
     RCC_LSEConfig(RCC_LSE_ON);
 
-    /* Wait till LSE is ready */
+    // Wait till LSE is ready
+    machine_uint_t sys_tick = sys_tick_counter;
     while((RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET) && (--timeout > 0)) {
     }
 
-    /* If LSE timed out, use LSI instead */
+    // record how long it took for the RTC to start up
+    rtc_info = (sys_tick_counter - sys_tick) << 2;
+
+    // If LSE timed out, use LSI instead
     if (timeout == 0) {
         // Disable the LSE OSC
         RCC_LSEConfig(RCC_LSE_OFF);
@@ -44,29 +56,35 @@ void rtc_init(void) {
         // Enable the LSI OSC
         RCC_LSICmd(ENABLE);
 
-        /* Wait till LSI is ready */
+        // Wait till LSI is ready
         while(RCC_GetFlagStatus(RCC_FLAG_LSIRDY) == RESET) {
         }
 
-        /* Use LSI as the RTC Clock Source */
+        // Use LSI as the RTC Clock Source
         RCC_RTCCLKConfig(RCC_RTCCLKSource_LSI);
+
+        // record that we are using the LSI
+        rtc_info |= RTC_INFO_USE_LSI;
     } else {
-        /* Use LSE as the RTC Clock Source */
+        // Use LSE as the RTC Clock Source
         RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);
+
+        // record that we are using the LSE
+        rtc_info |= RTC_INFO_USE_LSE;
     }
 
-    /* Note: LSI is around (32KHz), these dividers should work either way */
-    /* ck_spre(1Hz) = RTCCLK(LSE) /(uwAsynchPrediv + 1)*(uwSynchPrediv + 1)*/
+    // Note: LSI is around (32KHz), these dividers should work either way
+    // ck_spre(1Hz) = RTCCLK(LSE) /(uwAsynchPrediv + 1)*(uwSynchPrediv + 1)
     uint32_t uwSynchPrediv = 0xFF;
     uint32_t uwAsynchPrediv = 0x7F;
 
-    /* Enable the RTC Clock */
+    // Enable the RTC Clock
     RCC_RTCCLKCmd(ENABLE);
 
-    /* Wait for RTC APB registers synchronisation */
+    // Wait for RTC APB registers synchronisation
     RTC_WaitForSynchro();
 
-    /* Configure the RTC data register and RTC prescaler */
+    // Configure the RTC data register and RTC prescaler
     RTC_InitTypeDef RTC_InitStructure;
     RTC_InitStructure.RTC_AsynchPrediv = uwAsynchPrediv;
     RTC_InitStructure.RTC_SynchPrediv = uwSynchPrediv;
@@ -94,7 +112,13 @@ void rtc_init(void) {
 }
 
 /******************************************************************************/
-/* Micro Python bindings                                                      */
+// Micro Python bindings
+
+mp_obj_t pyb_rtc_info(void) {
+    return mp_obj_new_int(rtc_info);
+}
+
+MP_DEFINE_CONST_FUN_OBJ_0(pyb_rtc_info_obj, pyb_rtc_info);
 
 mp_obj_t pyb_rtc_read(void) {
     RTC_TimeTypeDef RTC_TimeStructure;
@@ -102,3 +126,5 @@ mp_obj_t pyb_rtc_read(void) {
     printf("%02d:%02d:%02d\n", RTC_TimeStructure.RTC_Hours, RTC_TimeStructure.RTC_Minutes, RTC_TimeStructure.RTC_Seconds);
     return mp_const_none;
 }
+
+MP_DEFINE_CONST_FUN_OBJ_0(pyb_rtc_read_obj, pyb_rtc_read);

stm/rtc.h

@@ -1,2 +1,4 @@
 void rtc_init(void);
-mp_obj_t pyb_rtc_read(void);
+
+MP_DECLARE_CONST_FUN_OBJ(pyb_rtc_info_obj);
+MP_DECLARE_CONST_FUN_OBJ(pyb_rtc_read_obj);