After sleeping for a maximum period ESP.deepSleep(ESP.deepSleepMax()), the ESP8266 wakes up to send a ping to IFTTT cloud. ESP.deepSleepMax() returns (uint64_t)system_rtc_clock_cali_proc()*(0x80000000-1)/(0x1000).
system_rtc_clock_cali_proc
| Function | Get RTC clock period |
|---|---|
| Prototype | uint32 system_get_rtc_time(void) |
| Parameter | none |
| Return | RTC clock period (in us); bit11 ~ bit0 are decimal. |
| Example | os_printf("clk cal : %d \r\n",system_rtc_clock_cali_proc()>>12); |
Note
// Setup: Edit all "secret" below for IFTTT and WiFi configurations
#include <ESP8266WiFi.h>
// Edit "secret" ssid and password below
const char* ssid = "secret";
const char* password = "secret";
// Set IFTTT Key from https://ifttt.com/services/maker_webhooks/settings
String iftttServiceName = "max_deep_sleep";
String iftttKey = "secret";
const char* host = "maker.ifttt.com";
const int httpPort = 80;
// Wakeup every 10,800,000,000 µs = 10800e6 = 10,800s = 3 hours
#define SLEEP_INTERVAL_DURATION 10800e6
void setup() {
Serial.begin(115200);
Serial.println("");
Serial.println("[INFO] Wake up!");
pinMode(LED_BUILTIN, OUTPUT);
connectWiFi();
blinkLED();
sendToIFTTT();
// Wakeup every 3h 45min
// But this only makes it wakeup periodically for 3 times only, not infinitely
// ESP.deepSleep(ESP.deepSleepMax());
Serial.println("[INFO] Going to sleep for 3 hours...");
ESP.deepSleep(SLEEP_INTERVAL_DURATION, WAKE_RF_DEFAULT);
}
void loop() {}
void blinkLED() {
Serial.println("LED ON");
digitalWrite(LED_BUILTIN, LOW);
delay(4000);
Serial.println("LED OFF");
digitalWrite(LED_BUILTIN, HIGH);
}
void connectWiFi() {
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.print("[INFO] WiFi connected with IP address: ");
Serial.println(WiFi.localIP());
}
void sendToIFTTT() {
WiFiClient client;
if (!client.connect(host, httpPort)) {
Serial.println("[ERROR] Connection failed");
return;
}
String url = "/trigger/max_deep_sleep/with/key/" + iftttKey;
client.print(String("GET ") + url + " HTTP/1.1\r\n" +
"Host: " + host + "\r\n" +
"User-Agent: ESP8266\r\n" +
"Connection: close\r\n\r\n");
// NOTE: cpplint rule runtime/int is ignored
// unsigned long is used instead of uint32 or uint64 because of millis()
unsigned long timeout = millis();
while (client.available() == 0) {
if (millis() - timeout > 5000) {
Serial.println("[ERROR] Client Timeout!");
return;
}
}
while (client.available()) {
String line = client.readStringUntil('\r');
Serial.print(line);
}
client.stop();
Serial.println("");
Serial.println("[INFO] Closing connection");
return;
}.PHONY: lint compile upload clean
lint:
cpplint --extensions=ino --filter=-legal/copyright,-readability/todo,-runtime/int *.ino
compile:
arduino-cli compile --fqbn esp8266com:esp8266:d1_mini ./
upload:
arduino-cli upload -p /dev/cu.wchusbserial1410 --fqbn esp8266com:esp8266:d1_mini ./
clean:
rm -f .*.bin
rm -f .*.elf
flash: lint compile upload clean