newlib: implement settimeofday, integrate LwIP SNTP, add SNTP example

components/esp32/Kconfig

@@ -324,7 +324,7 @@ choice ESP32_TIME_SYSCALL
 	default ESP32_TIME_SYSCALL_USE_RTC_FRC1
 	help
 		This setting defines which hardware timers are used to
-		implement 'gettimeofday' function in C library.
+		implement 'gettimeofday' and 'time' functions in C library.
 		
 		- If only FRC1 timer is used, gettimeofday will provide time at
 		  microsecond resolution. Time will not be preserved when going
@@ -336,8 +336,8 @@ choice ESP32_TIME_SYSCALL
 		  deep sleep, but time will be measured at 6.(6) microsecond
 		  resolution. Also the gettimeofday function itself may take 
 		  longer to run.
-		- If no timers are used, gettimeofday function return -1 and
-		  set errno to ENOSYS. 
+		- If no timers are used, gettimeofday and time functions
+		  return -1 and set errno to ENOSYS. 
 		  
 config ESP32_TIME_SYSCALL_USE_RTC
     bool "RTC"

components/lwip/Kconfig

@@ -24,6 +24,15 @@ config LWIP_SO_REUSE
         Enabling this option allows binding to a port which remains in
         TIME_WAIT.
 
+config LWIP_DHCP_MAX_NTP_SERVERS
+	int	"Maximum number of NTP servers"
+	default 1
+	range 1 16
+	help
+		Set maxumum number of NTP servers used by LwIP SNTP module.
+		First argument of sntp_setserver/sntp_setservername functions
+		is limited to this value. 
+
 endmenu
 
 

components/lwip/include/lwip/port/lwipopts.h

@@ -33,6 +33,8 @@
 #define __LWIPOPTS_H__
 
 #include <stdlib.h>
+#include <time.h>
+#include <sys/time.h>
 #include "esp_task.h"
 #include "sdkconfig.h"
 
@@ -552,7 +554,22 @@ extern unsigned char misc_prof_get_tcp_snd_buf(void);
 #define LWIP_NETCONN_FULLDUPLEX         1
 #define LWIP_NETCONN_SEM_PER_THREAD     1
 
+#define LWIP_DHCP_MAX_NTP_SERVERS       CONFIG_LWIP_DHCP_MAX_NTP_SERVERS
+#define LWIP_TIMEVAL_PRIVATE            0
 
+#define SNTP_SET_SYSTEM_TIME_US(sec, us)  \
+    do { \
+        struct timeval tv = { .tv_sec = sec, .tv_usec = us }; \
+        settimeofday(&tv, NULL); \
+    } while (0);
+
+#define SNTP_GET_SYSTEM_TIME(sec, us) \
+    do { \
+        struct timeval tv = { .tv_sec = 0, .tv_usec = 0 }; \
+        gettimeofday(&tv, NULL); \
+        (sec) = tv.tv_sec;  \
+        (us) = tv.tv_usec; \
+    } while (0);
 
 #define SOC_SEND_LOG //printf
 

components/newlib/time.c

@@ -20,6 +20,7 @@
 #include <sys/reent.h>
 #include <sys/time.h>
 #include <sys/times.h>
+#include <sys/lock.h>
 #include "esp_attr.h"
 #include "soc/soc.h"
 #include "soc/rtc_cntl_reg.h"
@@ -54,6 +55,15 @@ static uint64_t get_rtc_time_us()
 #endif // WITH_RTC
 
 
+// time from Epoch to the first boot time
+#ifdef WITH_RTC
+static RTC_DATA_ATTR struct timeval s_boot_time;
+#else
+static struct timeval s_boot_time;
+#endif
+static _lock_t s_boot_time_lock;
+
+
 #ifdef WITH_FRC1
 #define FRC1_PRESCALER 16
 #define FRC1_PRESCALER_CTL 2
@@ -83,7 +93,6 @@ void esp_setup_time_syscalls()
     s_microseconds = get_rtc_time_us();
 #endif //WITH_RTC
 
-
     // set up timer
     WRITE_PERI_REG(FRC_TIMER_CTRL_REG(0), \
             FRC_TIMER_AUTOLOAD | \
@@ -112,12 +121,12 @@ clock_t IRAM_ATTR _times_r(struct _reent *r, struct tms *ptms)
     return (clock_t) tv.tv_sec;
 }
 
-int IRAM_ATTR _gettimeofday_r(struct _reent *r, struct timeval *tv, void *tz)
+static uint64_t get_time_since_boot()
 {
-    (void) tz;
+    uint64_t microseconds = 0;
 #ifdef WITH_FRC1
     uint32_t timer_ticks_before = READ_PERI_REG(FRC_TIMER_COUNT_REG(0));
-    uint64_t microseconds = s_microseconds;
+    microseconds = s_microseconds;
     uint32_t timer_ticks_after = READ_PERI_REG(FRC_TIMER_COUNT_REG(0));
     if (timer_ticks_after > timer_ticks_before) {
         // overflow happened at some point between getting
@@ -127,13 +136,22 @@ int IRAM_ATTR _gettimeofday_r(struct _reent *r, struct timeval *tv, void *tz)
     }
     microseconds += (FRC_TIMER_LOAD_VALUE(0) - timer_ticks_after) / FRC1_TICKS_PER_US;
 #elif defined(WITH_RTC)
-    uint64_t microseconds = get_rtc_time_us();
+    microseconds = get_rtc_time_us();
 #endif
+    return microseconds;
+}
 
+int IRAM_ATTR _gettimeofday_r(struct _reent *r, struct timeval *tv, void *tz)
+{
+    (void) tz;
 #if defined( WITH_FRC1 ) || defined( WITH_RTC )
+    uint64_t microseconds = get_time_since_boot();
     if (tv) {
-        tv->tv_sec = microseconds / 1000000;
+        _lock_acquire(&s_boot_time_lock);
+        microseconds += s_boot_time.tv_usec;
+        tv->tv_sec = s_boot_time.tv_sec + microseconds / 1000000;
         tv->tv_usec = microseconds % 1000000;
+        _lock_release(&s_boot_time_lock);
     }
     return 0;
 #else
@@ -141,3 +159,24 @@ int IRAM_ATTR _gettimeofday_r(struct _reent *r, struct timeval *tv, void *tz)
     return -1;
 #endif // defined( WITH_FRC1 ) || defined( WITH_RTC )
 }
+
+int settimeofday(const struct timeval *tv, const struct timezone *tz)
+{
+    (void) tz;
+#if defined( WITH_FRC1 ) || defined( WITH_RTC )
+    if (tv) {
+        _lock_acquire(&s_boot_time_lock);
+        uint64_t now = ((uint64_t) tv->tv_sec) * 1000000LL + tv->tv_usec;
+        uint64_t since_boot = get_time_since_boot();
+        uint64_t boot_time = now - since_boot;
+
+        s_boot_time.tv_sec = boot_time / 1000000;
+        s_boot_time.tv_usec = boot_time % 1000000;
+        _lock_release(&s_boot_time_lock);
+    }
+    return 0;
+#else
+    __errno_r(r) = ENOSYS;
+    return -1;
+#endif
+}

examples/06_sntp/Makefile

@@ -0,0 +1,9 @@
+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+
+PROJECT_NAME := sntp
+
+include $(IDF_PATH)/make/project.mk
+

examples/06_sntp/README.md

@@ -0,0 +1,41 @@
+# Example: using LwIP SNTP module and time functions
+
+This example demonstrates the use of LwIP SNTP module to obtain time from Internet servers. See the README.md file in the upper level 'examples' directory for more information about examples.
+
+## Obtaining time using LwIP SNTP module
+
+When this example boots first time after ESP32 is reset, it connects to WiFi and obtains time using SNTP.
+See `initialize_sntp` function for details.
+
+## Timekeeping
+
+Once time is synchronized, ESP32 will perform timekeeping using built-in timers.
+
+- RTC clock is used to maintain accurate time when chip is in deep sleep mode
+
+- FRC1 timer is used to provide time at microsecond accuracy when ESP32 is running.
+
+Timekeeping using RTC timer is demonstrated in this example by going into deep sleep mode. After wake up, ESP32 will print current time without connecting to WiFi.
+
+To use this functionality, make sure "Timers used for gettimeofday function" option in "ESP32-specific config" menu of menuconfig is set to "RTC and FRC1" or "RTC".
+
+## Working with time
+
+To get current time, [`gettimeofday`](http://man7.org/linux/man-pages/man2/gettimeofday.2.html) function may be used. Additionally the following [standard C library functions](http://en.cppreference.com/w/cpp/header/ctime) can be used to obtain time and manipulate it:
+
+	gettimeofday
+	time
+	asctime
+	clock
+	ctime
+	difftime
+	gmtime
+	localtime
+	mktime
+	strftime
+
+To set time, [`settimeofday`](http://man7.org/linux/man-pages/man2/settimeofday.2.html) POSIX function can be used. It is used internally in LwIP SNTP library to set current time when response from NTP server is received.
+
+## Timezones
+
+To set local timezone, use [`setenv`](http://man7.org/linux/man-pages/man3/setenv.3.html) and [`tzset`](http://man7.org/linux/man-pages/man3/tzset.3.html) POSIX functions. First, call `setenv` to set `TZ` environment variable to the correct value depending on device location. Format of the time string is described in [libc documentation](https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html). Next, call `tzset` to update C library runtime data for the new time zone. Once these steps are done, `localtime` function will return correct local time, taking time zone offset and daylight saving time into account.

examples/06_sntp/main/Kconfig.projbuild

@@ -0,0 +1,17 @@
+menu "Example Configuration"
+
+config WIFI_SSID
+    string "WiFi SSID"
+	default "myssid"
+	help
+		SSID (network name) for the example to connect to.
+
+config WIFI_PASSWORD
+    string "WiFi Password"
+	default "myssid"
+	help
+		WiFi password (WPA or WPA2) for the example to use.
+
+		Can be left blank if the network has no security set.
+
+endmenu

examples/06_sntp/main/component.mk

@@ -0,0 +1,10 @@
+#
+# Main Makefile. This is basically the same as a component makefile.
+#
+# This Makefile should, at the very least, just include $(SDK_PATH)/make/component_common.mk. By default, 
+# this will take the sources in the src/ directory, compile them and link them into 
+# lib(subdirectory_name).a in the build directory. This behaviour is entirely configurable,
+# please read the ESP-IDF documents if you need to do this.
+#
+
+include $(IDF_PATH)/make/component_common.mk

examples/06_sntp/main/sntp_main.c

@@ -0,0 +1,163 @@
+/* LwIP SNTP example
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include <string.h>
+#include <time.h>
+#include <sys/time.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+#include "esp_system.h"
+#include "esp_wifi.h"
+#include "esp_event_loop.h"
+#include "esp_log.h"
+#include "esp_attr.h"
+#include "esp_deepsleep.h"
+#include "nvs_flash.h"
+
+#include "lwip/err.h"
+#include "apps/sntp/sntp.h"
+
+/* The examples use simple WiFi configuration that you can set via
+   'make menuconfig'.
+
+   If you'd rather not, just change the below entries to strings with
+   the config you want - ie #define EXAMPLE_WIFI_SSID "mywifissid"
+*/
+#define EXAMPLE_WIFI_SSID CONFIG_WIFI_SSID
+#define EXAMPLE_WIFI_PASS CONFIG_WIFI_PASSWORD
+
+/* FreeRTOS event group to signal when we are connected & ready to make a request */
+static EventGroupHandle_t wifi_event_group;
+
+/* The event group allows multiple bits for each event,
+   but we only care about one event - are we connected
+   to the AP with an IP? */
+const int CONNECTED_BIT = BIT0;
+
+static const char *TAG = "example";
+
+/* Variable holding number of times ESP32 restarted since first boot.
+ * It is placed into RTC memory using RTC_DATA_ATTR and
+ * maintains its value when ESP32 wakes from deep sleep.
+ */
+RTC_DATA_ATTR static int boot_count = 0;
+
+static void obtain_time(void);
+static void initialize_sntp(void);
+static void initialise_wifi(void);
+static esp_err_t event_handler(void *ctx, system_event_t *event);
+
+
+void app_main()
+{
+    ++boot_count;
+    ESP_LOGI(TAG, "Boot count: %d", boot_count);
+
+    time_t now;
+    struct tm timeinfo;
+    time(&now);
+    localtime_r(&now, &timeinfo);
+    // Is time set? If not, tm_year will be (1970 - 1900).
+    if (timeinfo.tm_year < (2016 - 1900)) {
+        ESP_LOGI(TAG, "Time is not set yet. Connecting to WiFi and getting time over NTP.");
+        obtain_time();
+        // update 'now' variable with current time
+        time(&now);
+    }
+    char strftime_buf[64];
+
+    // Set timezone to Eastern Standard Time and print local time
+    setenv("TZ", "EST5EDT,M3.2.0/2,M11.1.0", 1);
+    tzset();
+    localtime_r(&now, &timeinfo);
+    strftime(strftime_buf, sizeof(strftime_buf), "%c", &timeinfo);
+    ESP_LOGI(TAG, "The current date/time in New York is: %s", strftime_buf);
+
+    // Set timezone to China Standard Time
+    setenv("TZ", "CST-8CDT-9,M4.2.0/2,M9.2.0/3", 1);
+    tzset();
+    localtime_r(&now, &timeinfo);
+    strftime(strftime_buf, sizeof(strftime_buf), "%c", &timeinfo);
+    ESP_LOGI(TAG, "The current date/time in Shanghai is: %s", strftime_buf);
+
+    const int deep_sleep_sec = 10;
+    ESP_LOGI(TAG, "Entering deep sleep for %d seconds", deep_sleep_sec);
+    system_deep_sleep(1000000LL * deep_sleep_sec);
+}
+
+static void obtain_time(void)
+{
+    nvs_flash_init();
+    system_init();
+    initialise_wifi();
+    xEventGroupWaitBits(wifi_event_group, CONNECTED_BIT,
+                        false, true, portMAX_DELAY);
+    initialize_sntp();
+
+    // wait for time to be set
+    time_t now = 0;
+    struct tm timeinfo = { 0 };
+    int retry = 0;
+    const int retry_count = 10;
+    while(timeinfo.tm_year < (2016 - 1900) && ++retry < retry_count) {
+        ESP_LOGI(TAG, "Waiting for system time to be set... (%d/%d)", retry, retry_count);
+        vTaskDelay(2000 / portTICK_PERIOD_MS);
+        time(&now);
+        localtime_r(&now, &timeinfo);
+    }
+}
+
+static void initialize_sntp(void)
+{
+    ESP_LOGI(TAG, "Initializing SNTP");
+    sntp_setoperatingmode(SNTP_OPMODE_POLL);
+    sntp_setservername(0, "pool.ntp.org");
+    sntp_init();
+}
+
+static void initialise_wifi(void)
+{
+    tcpip_adapter_init();
+    wifi_event_group = xEventGroupCreate();
+    ESP_ERROR_CHECK( esp_event_loop_init(event_handler, NULL) );
+    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+    ESP_ERROR_CHECK( esp_wifi_init(&cfg) );
+    ESP_ERROR_CHECK( esp_wifi_set_storage(WIFI_STORAGE_RAM) );
+    wifi_config_t wifi_config = {
+        .sta = {
+            .ssid = EXAMPLE_WIFI_SSID,
+            .password = EXAMPLE_WIFI_PASS,
+        },
+    };
+    ESP_LOGI(TAG, "Setting WiFi configuration SSID %s...", wifi_config.sta.ssid);
+    ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_STA) );
+    ESP_ERROR_CHECK( esp_wifi_set_config(WIFI_IF_STA, &wifi_config) );
+    ESP_ERROR_CHECK( esp_wifi_start() );
+}
+
+static esp_err_t event_handler(void *ctx, system_event_t *event)
+{
+    switch(event->event_id) {
+    case SYSTEM_EVENT_STA_START:
+        esp_wifi_connect();
+        break;
+    case SYSTEM_EVENT_STA_GOT_IP:
+        xEventGroupSetBits(wifi_event_group, CONNECTED_BIT);
+        break;
+    case SYSTEM_EVENT_STA_DISCONNECTED:
+        /* This is a workaround as ESP32 WiFi libs don't currently
+           auto-reassociate. */
+        esp_wifi_connect();
+        xEventGroupClearBits(wifi_event_group, CONNECTED_BIT);
+        break;
+    default:
+        break;
+    }
+    return ESP_OK;
+}