ESP-8266: questions, questions

Things are going well with the ESP8266. After almost 72 hours I think that the conclusion may be that the test setup on the breadboard is working reliable; the ESP-12 has managed to come out of deep sleep and read a DS18B20 1-Wire sensor more than 12000 times without any glitch. That’s OK. I also found a way to interrupt the deep sleep it’s in by grounding RST; as far as I know this is the only way to accomplish this. It’s a somewhat strange interrupt of course, cause the ESP is not doing anything while it’s being interrupted … but hey, as long as it does what I need, I don’t care. Maybe wake-up call better describes what it actually is.

ESP-8266 ESP-12

To proceed further and find out whether the ESP-12 can be battery powered (with a minimal battery lifetime of 1 year) it’s time to do some measurements. The power it consumes seems to be documented, but I want to see it myself. Another interesting thing to know is: how long does it actually take the ESP start, connect to Wifi, initialize the GPIO, read the DS18B20, set up a TCP connection, send some data and go back to sleep. And what can be done to keep this period of high energy level as short as possible (or better: as energy-efficient as possible)? Compile the lua code with node.compile() perhaps? I’ll need a more recent firmware for that. And what’s the time from the wake-up call till the TCP server gets the data, short enough to use the ESP8266 for stuff like motion and such? How do I pull the pin to GND with a high signal from a PIR and how do I prevent re-triggering for some time? Questions …

A nice side project I’ll focus on first and for which I ordered some components today, is trying to get some more insight in the power consumption of the ESP-8266 to see if there’s any optimization possible there, without having to buy an expensive scope…

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6 Responses to ESP-8266: questions, questions

  1. Hari says:

    I’ve been measuring different ESP variants in deep sleep recently. Two ESP07 and an ESP01. With “node.dsleep(value)” (via nodemcu 0.9.5 20150213) they all consume around 0,37mA (measured with a recently calibrated HP 3478A). That is quite more than what I would have expected. I should receive an uCurrent gold this week and will do some more measurements.

    • Robert Hekkers says:

      My ESP-12 did 18 uA in deep sleep, measured with a 2-month old, but cheap meter. I’m now trying it in a different way, but no results yet…

  2. Hari says:

    After removing the LED on the esp-07 and the esp-01, they draw about 28-32uA when calling dsleep right after startup. I’ve measured that with the HP 3478A and with dave’s uCurrent gold, so I have high confidence in the values. Funny enough, the esp-07 only draws 23uA when it has been associated to the AP before going to dsleep. I’m not sure if you can trust your meter, even a Fluke 87V has issues here, it shows around 61uA…

    • Robert Hekkers says:

      I know, I don’t really have the right equipment for measuring currents in the range we’re dealing with here, so thanks for the numbers. I’m actually more interested in what happens during the time it’s awake and see if it’s possible to keep that as short as possible.

  3. Harald Klein says:

    I wanted to graph that tomorrow. Waking up, connecting to the AP, doing i2c sensor reading and calculation, transmitting via MQTT, and back to sleep.

    • Robert Hekkers says:

      Looking forward to reading about your results! 🙂
      I’ve come up with something that might work during the last few days and it’s quite cheap, more on that later

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