ESP8266 connecting to the network after ESP.deepSleepInstant() command

Question 1

Use WiFi.mode(WIFI_SHUTDOWN) before ESP.deepSleepInstant(). It cleanly turns Wi‑Fi off. On wake, set station mode, init ESP‑NOW, and add your peer on the known channel. “Try calling WiFi.mode(WIFI_SHUTDOWN) before calling deepSleepInstant().” How‑To: 1. WiFi.mode(WIFI_SHUTDOWN); ESP.deepSleepInstant(...). 2. After wake: WiFi.mode(WIFI_STA); esp_now_init(). 3. esp_now_add_peer(..., WIFI_CHANNEL, ...), then send. [Elektroda, khoam, post #19349251]

Answer

Use WiFi.mode(WIFI_SHUTDOWN) before ESP.deepSleepInstant(). It cleanly turns Wi‑Fi off. On wake, set station mode, init ESP‑NOW, and add your peer on the known channel. “Try calling WiFi.mode(WIFI_SHUTDOWN) before calling deepSleepInstant().” How‑To: 1. WiFi.mode(WIFI_SHUTDOWN); ESP.deepSleepInstant(...). 2. After wake: WiFi.mode(WIFI_STA); esp_now_init(). 3. esp_now_add_peer(..., WIFI_CHANNEL, ...), then send. [Elektroda, khoam, post #19349251]

Question 2

Real measurements showed about 300 ms from wake to reading BME280 and sending via ESP‑NOW. The largest current draw was around 60 mA for 100 ms. With correct setup, sub‑second cycles are achievable on batteries. [Elektroda, Zubiik, post #19349328]

Answer

Real measurements showed about 300 ms from wake to reading BME280 and sending via ESP‑NOW. The largest current draw was around 60 mA for 100 ms. With correct setup, sub‑second cycles are achievable on batteries. [Elektroda, Zubiik, post #19349328]

Question 3

Use the SparkFun BME280 library instead of Adafruit’s. One build measured about 233 ms from reset to sleeping again after switching. Keep the sensor in forced mode and take one sample per wake to minimize time active. [Elektroda, Zubiik, post #19350960]

Answer

Use the SparkFun BME280 library instead of Adafruit’s. One build measured about 233 ms from reset to sleeping again after switching. Keep the sensor in forced mode and take one sample per wake to minimize time active. [Elektroda, Zubiik, post #19350960]

Question 4

Adafruit_BME280::init() ends with delay(100), which adds startup latency. You can try reducing that delay and validate readings. Or switch to a driver without that pause. “You can change this delay(100) to e.g. delay(10) and check that it initialises correctly.” [Elektroda, khoam, post #19349632]

Answer

Adafruit_BME280::init() ends with delay(100), which adds startup latency. You can try reducing that delay and validate readings. Or switch to a driver without that pause. “You can change this delay(100) to e.g. delay(10) and check that it initialises correctly.” [Elektroda, khoam, post #19349632]

Question 5

Changing timing in the calibration phase can break measurements and return NaN. Keep the calibration wait intact. If you reduce the final delay, test across many wakes to ensure stability. Consider an alternative library if problems persist. [Elektroda, Zubiik, post #19349640]

Answer

Changing timing in the calibration phase can break measurements and return NaN. Keep the calibration wait intact. If you reduce the final delay, test across many wakes to ensure stability. Consider an alternative library if problems persist. [Elektroda, Zubiik, post #19349640]

Question 6

No. ESP8266 has no hardware I2C; Wire is bit‑banged. Fast‑mode 400 kHz is unreliable. Use conservative speeds that your code and sensor can sustain. “There is no I2C hardware controller on the ESP8266, so 400 kHz is a pipe dream.” [Elektroda, khoam, post #19349632]

Answer

No. ESP8266 has no hardware I2C; Wire is bit‑banged. Fast‑mode 400 kHz is unreliable. Use conservative speeds that your code and sensor can sustain. “There is no I2C hardware controller on the ESP8266, so 400 kHz is a pipe dream.” [Elektroda, khoam, post #19349632]

Question 7

Tests showed it did not change timing. It lowered instantaneous RF power and current instead. Keep it for energy or emission limits, but do not expect faster wake‑to‑send. [Elektroda, Zubiik, post #19348836]

Answer

Tests showed it did not change timing. It lowered instantaneous RF power and current instead. Keep it for energy or emission limits, but do not expect faster wake‑to‑send. [Elektroda, Zubiik, post #19348836]

Question 8

Yes, when your channel is fixed. Using ESP.deepSleep(..., WAKE_NO_RFCAL) enabled quick ESP‑NOW reconnection, with about 300 ms total time observed. Skipping RF calibration trims wake overhead. [Elektroda, Zubiik, post #19348836]

Answer

Yes, when your channel is fixed. Using ESP.deepSleep(..., WAKE_NO_RFCAL) enabled quick ESP‑NOW reconnection, with about 300 ms total time observed. Skipping RF calibration trims wake overhead. [Elektroda, Zubiik, post #19348836]

Question 9

Yes. Pulling CHIP_EN low powers the ESP8266 off even more than deep‑sleep. You will need an external RTC or alarm circuit to wake it periodically by toggling enable or reset. [Elektroda, krzbor, post #19357162]

Answer

Yes. Pulling CHIP_EN low powers the ESP8266 off even more than deep‑sleep. You will need an external RTC or alarm circuit to wake it periodically by toggling enable or reset. [Elektroda, krzbor, post #19357162]

Question 10

CHIP_EN low removes power from the whole chip. RTC memory does not retain contents in this state. Do not rely on RTC retention when power‑gating via CHIP_EN. [Elektroda, khoam, post #19357931]

Answer

CHIP_EN low removes power from the whole chip. RTC memory does not retain contents in this state. Do not rely on RTC retention when power‑gating via CHIP_EN. [Elektroda, khoam, post #19357931]

Question 11

Startup time includes the boot ROM “spitting out diagnostic information on the UART.” Disabling it requires rebuilding Arduino Core and the underlying NonOS SDK. Plan this fixed overhead into your energy budget. [Elektroda, khoam, post #19358628]

Answer

Startup time includes the boot ROM “spitting out diagnostic information on the UART.” Disabling it requires rebuilding Arduino Core and the underlying NonOS SDK. Plan this fixed overhead into your energy budget. [Elektroda, khoam, post #19358628]

Question 12

Use RTC memory to store minimal state, such as last readings or init flags. After wake, replay configuration and skip full driver initialization when safe. This can further shorten active time. [Elektroda, khoam, post #19353109]

Answer

Use RTC memory to store minimal state, such as last readings or init flags. After wake, replay configuration and skip full driver initialization when safe. This can further shorten active time. [Elektroda, khoam, post #19353109]

Question 13

Start with measured energy per cycle. One build observed roughly 7 mAs per read+send. Multiply by wake frequency to budget capacity. Validate your math with new measurements after each change. [Elektroda, Zubiik, post #19353095]

Answer

Start with measured energy per cycle. One build observed roughly 7 mAs per read+send. Multiply by wake frequency to budget capacity. Validate your math with new measurements after each change. [Elektroda, Zubiik, post #19353095]

Question 14

Use WiFi.mode(WIFI_STA) at startup. It did not change timing in tests, and leaving station mode enabled kept ESP‑NOW working correctly. Then initialize ESP‑NOW and add peers. [Elektroda, Zubiik, post #19348836]

Answer

Use WiFi.mode(WIFI_STA) at startup. It did not change timing in tests, and leaving station mode enabled kept ESP‑NOW working correctly. Then initialize ESP‑NOW and add peers. [Elektroda, Zubiik, post #19348836]

Question 15

A non‑zero return means initialization failed. Shut Wi‑Fi down before sleeping, then reinitialize on wake. “Try calling WiFi.mode(WIFI_SHUTDOWN) before calling deepSleepInstant().” Verify you add the peer on the correct channel and retry if needed. [Elektroda, khoam, post #19349251]

Answer

A non‑zero return means initialization failed. Shut Wi‑Fi down before sleeping, then reinitialize on wake. “Try calling WiFi.mode(WIFI_SHUTDOWN) before calling deepSleepInstant().” Verify you add the peer on the correct channel and retry if needed. [Elektroda, khoam, post #19349251]

ESP8266 connecting to the network after ESP.deepSleepInstant() command

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