![]() ![]() The type "uint64_t" sets a specific limit for the amount of microseconds that could be passed to the function, approximately something that amounts to 3 hours.īut browsing the specifics and some online resources, it's clearly stated that the ESP32, unlike the ESP8266, is able to deep sleep for over a year.īut how can I achieve such a thing? I mean, I don't need an entire year, but at least 8-9 hours. Even though I'm using Arduino as the IDE, I'm still using the 2 functions provided by espressif libraries, which are:Įsp_err_t esp_sleep_enable_timer_wakeup(uint64_t time_in_us) I'm able to send the device to sleep for a little over 3 hours maximum, but if I insert a higher amount of time (expressed in microseconds) it causes an overflow. The issue I'm having is about the DeepSleep feature. The board is ESP32-based, from WaveShare displays. This article is a good tutorial on deep sleep and has more information.I'm currently working on a IoT project. It really depends on the device and the circuitry. If they remain powered they may retain their state from the previous cycle. Whether the devices remain powered and how they react to the GPIO lines floating depends on the device. The ESP32 will stop powering its GPIO lines during deep sleep. How deep sleep affects any electronics connected to the ESP32 is difficult to predict. Storing pointers to data (like a char* pointing to a C string) will not work because the data the pointer pointed to will be lost after restarting from deep sleep. Storing complex C++ objects in it will almost certainly not work correctly across deep sleep restarts. There's only 8KB of static RAM so you can't store huge amounts of data there. For instance: RTC_DATA_ATTR unsigned wakeups You can declare a variable to live in the RTC RAM using RTC_DATA_ATTR. Its contents will be lost or cleared when the ESP32 loses power or is flashed. This RAM is built into the ESP32 and is maintained during deep sleep. You can also store data in the static RAM that's part of the real-time-clock (RTC). Writing to flash is slow and costs a lot of power, so this isn't great if you're running off a battery. Obviously you can store data in flash memory using EEPROM or SPIFFS. There are a couple of ways to preserve state across sleep cycles. ![]() Your setup() function will run again and will need to do any initialization again. So when it restarts out of deep sleep it's as if it just powered up. It costs power to maintain the contents of its memory and the CPU state, and the point of deep sleep is to save as much power as possible, so it stops powering these things. The contents of memory and the current state of the processor are lost. When the ESP32 enters deep sleep, it turns off the processor that's running your code. Serial.println(F("Failed to read from DHT sensor!")) īool ok = network.write(header, &pack0, sizeof(pack0)) If (isnan(pack0.humidity) || isnan(pack0.temperature)) ![]() Pack0.soil = map(analogRead(SOILPIN), 0, 4096, 100, 0) //convert to percentage Pack0.temperature = dht.readTemperature() put your main code here, to run repeatedly: My code is attached below struct package0 So is all my void setup() code wiped out? Or just my pack0.temp, humid, soil is wiped out? Can I use deep sleep for my project?Įverything stored in that memory is wiped out and cannot be accessed. My next step is to put my slave in sleep mode (maybe deep sleep). I'm doing wireless sensor node using esp32 (slave) and rf24l01 module. ![]()
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