Further reducing power consumption on ESP8266

By carefully rearranging the operations my weather station does each time it wakes up, I have reduced the power consumption even further.

As it wakes up, it needs to make a series of measurements:

  • Read the current battery voltage
  • Read the current temperature from a DHT22
  • Read the current humidity from a DHT22
  • Read the current temperature from a BMP180
  • Read the current air pressure from a BMP180

The battery voltage is read through a resistor voltage divider feeding into the analog input of the ESP8266.  This reading is very sensitive, and a massive power drain from the WiFi function will bring down the measured voltage.  This can be mitigated by using capacitors to buffer the analog readings, but if I have a choice I’d still prefer to have the WiFi function off when reading this.

The rest of the readings, however, are digital and not that sensitive to overall system power drain, and that gives us an opportunity to do things in parallel.

Continue reading “Further reducing power consumption on ESP8266”

Reducing WiFi power consumption on ESP8266, part 3

Welcome to part 3 of this series on reducing WiFi power consumption on ESP8266 chips.

Earlier, I have established the baseline power consumption and shown how to reduce this a bit by disabling the radio when it is not needed.

This time, I’ll take it a step further by showing how to make sure the radio is needed for a shorter period of time.

Continue reading “Reducing WiFi power consumption on ESP8266, part 3”

Reducing WiFi power consumption on ESP8266, part 2

In my previous post I showed the baseline power consumption data for one of my ESP8266-based weather monitors.

The device wakes up from deep sleep, reads some sensors, connects to a WiFi network and transmits the readings over MQTT, it will then go back to sleep for 5 minutes.  One such reporting cycle would consume 0.164 mAh.

This time I’ll show the first steps on the way to reducing this to less than half.

Continue reading “Reducing WiFi power consumption on ESP8266, part 2”

Reducing WiFi power consumption on ESP8266, part 1

The ESP8266 is a brilliant little chip, one I am using for a lot of network connected devices such as weather stations, lighting controllers, environment monitors, etc.

For a lot of these, it is important to be able to run for extended periods on batteries.  Several will be in places where there is no power connections, and I don’t want to run around changing batteries all the time.

After experimenting for a while, I had a weather station which could operate for 3 weeks on 4 AAA batteries.  Not too bad, considering the device had WiFi connectivity and would transmit the current readings back to my server every 5 minutes.  However, it is possible to achieve much better results than this. Continue reading “Reducing WiFi power consumption on ESP8266, part 1”

Too many joins in query

In Dynamics AX 2012, if you are running a query with too many joins you can get an error or warning message saying “The number of joins in the statement is XX.  This exceeds the maximum of 26.  Turn on exception for this warning to see the call stack.”

So what is this, and what can you do about it?

Continue reading “Too many joins in query”