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• Revision C

  Miroslav Zuzelka • 04/10/2017 at 12:04 • 0 comments

  This is my last revision which a did so far.

  It contain following parts:

  • ESP12E
  • 3.3V voltage regulator LM1117
  • Reset button
  • Flash button
  • FTDI connector
  • LCD connector
  • Some resistors
  • Some capacitors
  • LED for flash state
  • build in charging with MCP73831T + LED indicator
  • auto-reset feature
  • USB to Serial converter chip CH340G

  Charging & auto reset circuit is copy of same circuit which Adafruit have on Adafruit Feather HUZZAH with ESP8266 WiFi . USB to Serial part is from Nodemcu github documentation page. Because I want in the future monitor battery voltage (when board is not connected to power source), I placed 2 resistors on analog input of ESP and connect it to battery positive contact. This way I can monitor how much voltage is comming from battery and possibly send message that battery should be connected to power source.

  Here is schematic:

  Board design:

  Here is how board look when is populated. Both previous revision have wire connections, this board is double sided becuase it would be to many wire connections.

  I assembled board in this manner:

  • I placed solder paste on pads which will be populated with SMD parts (resistors, capacitors, LEDs, buttons, ICs, etc.)
  • I placed all SMD components on the board and run it through the reflow owen
  • I checked all components for shorts after reflowing
  • I checked voltage on pads where should be 3.3V and I found out that half of the board is without power
  • Made test with continuity meater and find out that ground is not completely connected -> fixed problem with black wire in right low corner
  • I soldered crystal for USB to serial chip and tested if PC will recognize it -> PASSED
  • I soldered ESP12E and tryed programm it with USB -> NOT PASSED
  • I tryed to programm it with flash button -> PASSED
  • I soldered header for LCD and tested board with it -> PASSED
  • I soldered header for battery and tryed to charge it -> PASSED

  So far so good. Here is how fineshed board look like:
  

  Ok, board is working, but is everything OK? No.

  • I found out that one transistor from auto reset circuit was not centered enough on pads and it was not working, thats why auto-reset did not work. I desoldered it and solder in right way and that fixed this problem. Next try of programming through USB fineshed without problem.
  • When battery is connected and charging is in progress, LED for charging should light up but it is not working -> I had no time to fix this yet.
  • Battery power monitor is not working -> I measured voltage on analog pin of the ESP and there is something like 9V!! I was thinking why and after while a realized that I soldered wrong value of resistors on analog pin line. I placed 68R and 220R insted of 68K and 220K resistors. I had no time to fix this yet.

  Here is more pictures of finished board:
  

  Conclusion
  

  Revision C board is finished and I think it is success. If I want simple board which will have same functions as orginal project from Squix78 and Ruiz Brothers it would be done, but so far I completed 3 from 7 tasks.

  Thanks for your time with my project and that´s all for this revision, if you have any question, let me know in discussion ;-).
  

• Revision B

  Miroslav Zuzelka • 04/10/2017 at 12:03 • 0 comments

  So Revision B,

  this is exactly same design as Revison A, just with fixed mistakes.

  Schematic is same:

  Board design looks like this:

  I rearranged parts so board looks more symetric and I changed buttons for bigger one.

  If you wondering why are vias so big, that is beacause if I will make them small, they will be hard to solder or they will fall of the board. Because my friend don´t make vias like normal PCB factory, I must have this in mind when I design my boards. It´s not big problem for me, but you have to think about it when you make your design. Again I have no picture of the board when I picked it up so here is board how look like now:

  I had no problem with this revision = I don´t have to fix something :-p ;-).

  Are you asking how do I flash it? It is same procedure like with any EPS without auto-reset feature: when you are holding flash button, you press reset button and it will jump in the programming mode and you can cklick Upload button in your Arduino IDE ;-).

  Here is result of that procedure:

  Here is how it looks like in the dark:

  That´s all for this revision, if you have any question, let me know in discussion ;-).

  See you soon with another revision.

• Revision A

  Miroslav Zuzelka • 04/10/2017 at 12:00 • 0 comments

  In my first revision I decided to go easy at first, so I made simple board which will contain these components:

  • ESP12E
  • 3.3V voltage regulator LM1117
  • Reset button
  • Flash button
  • FTDI connector
  • LCD connector
  • Some resistors
  • Some capacitors
  • LED for flash state

  I draw everything in Eagle and schematic looks like this:

  Then I placed all parts where I thoughed will be appropriate :

  After that I send my design to one of my friend which make PCB here in Czech Republic (www.plosnaky.cz) , waited for few days and pick one up. Sadly I have no picture before I start assembly of the board so here is how first board look like when I fineshed it.

  How you can see my first design is not perfect. When I start testing of the board, I found out that I forget to make connection between 3.3V and LCD so for this is the red cable. Also I had bit of problem with power for ESP12E so I added silver "jumper" wire. After that board was working so I learn my mystakes and fixed them in revision B of the board.

  This board take power from FTDI connection which you can see on left side of the board.

  
  

• Begininig

  Miroslav Zuzelka • 04/10/2017 at 11:59 • 0 comments

  At first, I want to write down what I want to do in this project:
  

  1. Make PCB with ESP12E
  2. Add USB to Serial converter
  3. Add battery & charging circuit
  4. Add touch TFT LCD & modify source code for it
  5. Add some humidity/temperature/preasure sensor (DHT11/22, BMP180) & modify source code for it
  6. Make custom enclosure (possibly similar to Ruiz Brothers)
  7. Have fun with it

  So I had in my drawer for some time this TFT LCD and after what I saw project at Adafruit I decide to use it for this build. I looked at Squix Github for description of connection, and made it work with Nodemcu in breadboard:

  To make it completely work, you have to connect to the AP which Nodemcu created (AP will be always on IP address 192.168.4.1 ):

  Click on Configure Wifi

  Select network, insert password and click Save

  When is everything OK, Nodemcu will tell you so and it will connect to that selected network.

  After that will download files which are necessary for weather station sketch and will start up.

  After that I did know that it will work, so I started my project in Autodesk (Cadsoft) Eagle. I will make separate log for every revision of my PCB so look at those if you are still interested in this project.

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