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UnderConstruction
This is my second project with the Esp-12-e module that contains the famous esp8266 from Espressif.
This sensor will connect to my Mqtt broker and send data to it. The broker will then with the help of Node red store it in an sqlite database and make some nice charts of it.
There are other similar sensor on the web, but I like to design and make my own. It’s my hobby and work.
The software will be writen with the Arduino ide for simple and quick design.
This is my second design now with Altium desiger. Switched from Eagle to Altium because Eagle has it’s limitation, not for this design but for more complexer. This board was not to difficult to start learning using Altium, and if I messed it up also not to expensive.

The hart of the board is the Esp-12-e module with a DHT22 Temperature and humidity sensor, all powered from a 16340 Li-ion battery that must last for at least a year. That’s what we hope.
The board contains also a ldo voltage regulator, led for debugging etc, some extra pads for  “you never know in the future” and a programming socket. This socket is only used ones to program in the OTA and after that updating the firmware can be done over the air.

For now there’s nothing more to see then the 3D images from Altium Designer. Pcb’s are ordered in China and I have to wait for 2~4 weeks before they are here.
The picture is the panalized version, but the download version is a single board.

 

Update 3/10/2016:
Boards are in.
After some quick testing the esp8266 was not always starting up. My mistake, I forgot the pull-up resistor(12k) on gpio2.
The esp8266 determines with the help of gpio 0,2 and 15 how it will boot. With the gpio2 floating this gave problems.
esp8266startup

Added the pull-up resistor (R7) already to the Altium files below. If there are no more errors maybe I going order some new pcb’s.

 

Update 14/10/2016:
I wrote a small test program to test the hardware and get some numbers out and from it. You can find the test program on github.
Hardware is working fine. DHT22 (btw is official a AM2302, see source ) temperature reading is slightly different from my (also uncalibrated) temperature meter. 0.4 °C is more then the 0.2°C according the datasheet, but I’m not sure how accurate the temperature meter is.
Humidity is even harder to say if it’s correct because I don’t have anything to compare with.
Current consumption is around 27μA with a supply voltage of 3.6V.
Calculated is 10μA for the Esp8266 + 8μA for the battery measure voltage divider + 4μA for the LDO quiescent current = 22μA.  Not bad result.
Because you can switch off the DHT22 completely by removing the power supply from it (gpio5) your not draining the additional 500μA standby current for this sensor. This will result in longer battery lifetime.

 

 

Altium 16 Design files V3

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