esp8266 · d-a-v · Apr 9, 2021 · Mar 2, 2021 · Mar 2, 2021 · Mar 3, 2021
diff --git a/cores/esp8266/core_esp8266_features.h b/cores/esp8266/core_esp8266_features.h
@@ -31,6 +31,7 @@
 #define CORE_HAS_UMM
 
 #define WIFI_HAS_EVENT_CALLBACK
+#define WIFI_IS_OFF_AT_BOOT
 
 #include <stdlib.h> // malloc()
 #include <stddef.h> // size_t
@@ -104,6 +105,8 @@ uint64_t micros64(void);
 void delay(unsigned long);
 void delayMicroseconds(unsigned int us);
 
+void enableWiFiAtBootTime (void) __attribute__((noinline));
+
 #if defined(F_CPU) || defined(CORE_MOCK)
 #ifdef __cplusplus
 constexpr

diff --git a/cores/esp8266/core_esp8266_main.cpp b/cores/esp8266/core_esp8266_main.cpp
@@ -332,7 +332,18 @@ extern "C" void app_entry (void)
 extern "C" void preinit (void) __attribute__((weak));
 extern "C" void preinit (void)
 {
-    /* do nothing by default */
+    /* does nothing, kept for backward compatibility */
+}
+
+extern "C" void __disableWiFiAtBootTime (void) __attribute__((weak));
+extern "C" void __disableWiFiAtBootTime (void)
+{
+    // Starting from arduino core v3: wifi is disabled at boot time
+    // WiFi.begin() or WiFi.softAP() will wake WiFi up
+    wifi_set_opmode_current(0/*WIFI_OFF*/);
+    wifi_fpm_set_sleep_type(MODEM_SLEEP_T);
+    wifi_fpm_open();
+    wifi_fpm_do_sleep(0xFFFFFFF);
 }
 
 extern "C" void user_init(void) {
@@ -360,7 +371,8 @@ extern "C" void user_init(void) {
 #if defined(MMU_IRAM_HEAP)
     umm_init_iram();
 #endif
-    preinit(); // Prior to C++ Dynamic Init (not related to above init() ). Meant to be user redefinable.
+    preinit(); // deprecated
+    __disableWiFiAtBootTime(); // default weak function disables WiFi
 
     ets_task(loop_task,
         LOOP_TASK_PRIORITY, s_loop_queue,

diff --git a/cores/esp8266/coredecls.h b/cores/esp8266/coredecls.h
@@ -18,6 +18,7 @@ void esp_schedule();
 void tune_timeshift64 (uint64_t now_us);
 void disable_extra4k_at_link_time (void) __attribute__((noinline));
 bool sntp_set_timezone_in_seconds(int32_t timezone);
+void __disableWiFiAtBootTime (void) __attribute__((noinline));
 void __real_system_restart_local() __attribute__((noreturn));
 
 uint32_t sqrt32 (uint32_t n);
@@ -34,6 +35,6 @@ using TrivialCB = std::function<void()>;
 void settimeofday_cb (const BoolCB& cb);
 void settimeofday_cb (const TrivialCB& cb);
 
-#endif
+#endif // __cplusplus
 
 #endif // __COREDECLS_H
diff --git a/cores/esp8266/enable_wifi_at_boot_time.cpp b/cores/esp8266/enable_wifi_at_boot_time.cpp
@@ -0,0 +1,20 @@
+/*
+ *  empty wrappers to play with linker and reenable wifi at boot time
+ */
+
+#include "coredecls.h"
+
+extern "C" void enableWiFiAtBootTime()
+{
+    /*
+     * Called by user from anywhere, does nothing and allows overriding
+     * the core_esp8266_main.cpp's default disableWiFiAtBootTime() by the
+     * one below, at link time.
+     */
+}
+
+extern "C" void __disableWiFiAtBootTime()
+{
+    // overrides the default __disableWiFiAtBootTime:
+    // Does nothing: WiFi is enabled by default in nonos-sdk
+}
diff --git a/libraries/ESP8266WiFi/examples/EarlyDisableWiFi/EarlyDisableWiFi.ino b/libraries/ESP8266WiFi/examples/EarlyDisableWiFi/EarlyDisableWiFi.ino
diff --git a/libraries/ESP8266WiFi/examples/WiFiShutdown/WiFiShutdown.ino b/libraries/ESP8266WiFi/examples/WiFiShutdown/WiFiShutdown.ino
@@ -24,11 +24,6 @@ WiFiState state;
 const char* ssid = STASSID;
 const char* password = STAPSK;
 
-void preinit(void) {
-  // Make sure, wifi stays off after boot.
-  ESP8266WiFiClass::preinitWiFiOff();
-}
-
 void setup() {
   Serial.begin(74880);
   //Serial.setDebugOutput(true);  // If you need debug output

diff --git a/libraries/ESP8266WiFi/src/ESP8266WiFiGeneric.cpp b/libraries/ESP8266WiFi/src/ESP8266WiFiGeneric.cpp
@@ -419,7 +419,7 @@ bool ESP8266WiFiGenericClass::mode(WiFiMode_t m, WiFiState* state) {
     }
 
     if (wifi_fpm_get_sleep_type() != NONE_SLEEP_T) {
-        // wifi may have been put asleep by ESP8266WiFiGenericClass::preinitWiFiOff
+        // wifi starts asleep by default
         wifi_fpm_do_wakeup();
         wifi_fpm_close();
     }
@@ -855,25 +855,7 @@ bool ESP8266WiFiGenericClass::resumeFromShutdown (WiFiState* state)
     return true;
 }
 
-//meant to be called from user-defined ::preinit()
 void ESP8266WiFiGenericClass::preinitWiFiOff () {
-  // https://github.com/esp8266/Arduino/issues/2111#issuecomment-224251391
-  // WiFi.persistent(false);
-  // WiFi.mode(WIFI_OFF);
-  // WiFi.forceSleepBegin();
-
-  //WiFi.mode(WIFI_OFF) equivalent:
-  // datasheet:
-  // Set Wi-Fi working mode to Station mode, SoftAP
-  // or Station + SoftAP, and do not update flash
-  // (not persistent)
-  wifi_set_opmode_current(WIFI_OFF);
-
-  //WiFi.forceSleepBegin(/*default*/0) equivalent:
-  // sleep forever until wifi_fpm_do_wakeup() is called
-  wifi_fpm_set_sleep_type(MODEM_SLEEP_T);
-  wifi_fpm_open();
-  wifi_fpm_do_sleep(0xFFFFFFF);
-
-  // use WiFi.forceSleepWake() to wake WiFi up
+    // It was meant to be called from user-defined ::preinit()
+    // It is now deprecated by enableWiFiAtBootTime() and __disableWiFiAtBootTime()
 }
diff --git a/libraries/ESP8266WiFi/src/ESP8266WiFiGeneric.h b/libraries/ESP8266WiFi/src/ESP8266WiFiGeneric.h
@@ -133,7 +133,7 @@ class ESP8266WiFiGenericClass {
 
         static uint32_t shutdownCRC (const WiFiState* state);
         static bool shutdownValidCRC (const WiFiState* state);
-        static void preinitWiFiOff (); //meant to be called in user-defined preinit()
+        static void preinitWiFiOff () __attribute__((deprecated("WiFi is off by default at boot, use enableWiFiAtBoot() for legacy behavior")));
 
     protected:
         static bool _persistent;

diff --git a/libraries/esp8266/examples/SerialStress/SerialStress.ino b/libraries/esp8266/examples/SerialStress/SerialStress.ino
@@ -57,12 +57,6 @@ void error(const char* what) {
   }
 }
 
-void preinit() {
-  // (no C++ in function)
-  // disable wifi
-  ESP8266WiFiClass::preinitWiFiOff();
-}
-
 void setup() {
   pinMode(LED_BUILTIN, OUTPUT);
 

diff --git a/libraries/esp8266/examples/UartDownload/UartDownload.ino b/libraries/esp8266/examples/UartDownload/UartDownload.ino
@@ -98,12 +98,6 @@ void proxyEspSync() {
 //
 ////////////////////////////////////////////////////////////////////////////////
 
-void preinit() {
-  // (no C++ in function)
-  // disable wifi
-  ESP8266WiFiClass::preinitWiFiOff();
-}
-
 void setup() {
   // For `proxyEspSync()` to work, the Serial.begin() speed needs to be
   // 115200bps. This is the data rate used by esptool.py. It expects the Boot

diff --git a/libraries/lwIP_w5500/examples/TCPClient/TCPClient.ino b/libraries/lwIP_w5500/examples/TCPClient/TCPClient.ino
@@ -9,7 +9,6 @@
 //or #include <ENC28J60lwIP.h>
 
 #include <WiFiClient.h> // WiFiClient (-> TCPClient)
-#include <ESP8266WiFi.h> // ESP8266WiFiClass::preinitWiFiOff()
 
 const char* host = "djxmmx.net";
 const uint16_t port = 17;
@@ -19,12 +18,6 @@ using TCPClient = WiFiClient;
 #define CSPIN 16 // wemos/lolin/nodemcu D0
 Wiznet5500lwIP eth(CSPIN);
 
-void preinit() {
-  // (no C++ in function)
-  // disable wifi
-  ESP8266WiFiClass::preinitWiFiOff();
-}
-
 void setup() {
   Serial.begin(115200);
 

diff --git a/tests/device/test_serial/test_serial.ino b/tests/device/test_serial/test_serial.ino
@@ -33,12 +33,6 @@ static uint64_t in_total = 0, in_prev = 0;
 static uint64_t start_ms, last_ms;
 static uint64_t timeout;
 
-void preinit() {
-  // (no C++ in function)
-  // disable wifi
-  ESP8266WiFiClass::preinitWiFiOff();
-}
-
 void setup()
 {
   Serial.begin(SSBAUD);

diff --git a/tests/device/test_spi_flash/test_spi_flash.ino b/tests/device/test_spi_flash/test_spi_flash.ino
@@ -3,12 +3,6 @@
 
 BS_ENV_DECLARE();
 
-void preinit() {
-    // (no C++ in function)
-    // disable wifi
-    ESP8266WiFiClass::preinitWiFiOff();
-}
-
 void setup()
 {
     Serial.begin(115200);