Added a README.md.

Author: CelliesProjects

README.md

@@ -0,0 +1,64 @@
+# smartMeterLogger-esp32
+
+## About
+
+`smartMeterLogger-esp32` connects to a smart meter (slimme meter) and logs the electricity use per minute  to an sdcard. 
+
+![screenshot](img/screenshot.png)
+
+![screenshot](img/screenshot_android.png)
+
+## How to use
+
+1. Change your credentials in `wifisetup.h`.
+1. (Optional) In `smartMeterLogger-esp32.ino` uncomment `#define SH1106_OLED` if you compile for sh1106 instead of ssd1306 and set the i2c pins (and address) for your oled screen.
+3. Save all files and flash the sketch to your esp32.
+4. Connect your esp32 to the smart meter. [See here how](https://github.com/matthijskooijman/arduino-dsmr#connecting-the-p1-port).<br>Take note that to connect to the esp32 the `DATA` signal has to be inverted and level shifted.
+5. If you added a ssd1306/sh1106 oled screen, the ip address will be visible on the screen.<br>If there is no oled you can check the ip address on the serial port in the Arduino IDE.
+6. Browse to the ip address of your esp32 to see your current energy use.
+
+If you have a garbled screen you most likely compiled for the wrong oled type.<br>Try to comment/uncomment `#define SH1106_OLED` to solve this.
+
+## Needed libraries
+
+- [https://github.com/me-no-dev/AsyncTCP](https://github.com/me-no-dev/AsyncTCP)
+- [https://github.com/me-no-dev/ESPAsyncWebServer](https://github.com/me-no-dev/ESPAsyncWebServer)
+- [https://github.com/matthijskooijman/arduino-dsmr](https://github.com/matthijskooijman/arduino-dsmr)
+
+Download and install these in the Arduino libraries folder.
+
+The driver library for a ssd1306/sh1106 oled can be installed with the Arduino library manager. Use the ThingPulse driver.
+
+## DSMR v5 P1 port standard specifications
+
+[DSMR v5.0.2 P1 Companion Standard.pdf](https://github.com/matthijskooijman/arduino-dsmr/blob/master/specs/DSMR%20v5.0.2%20P1%20Companion%20Standard.pdf)
+
+## Hardware
+
+### ESP32: LilyGo TTGO T7 with external antenna
+
+My personal preference is for the LilyGo TTGO T7. The LilyGo TTGO T7 is a good board with an external antenna connector and a decent 3.3v LDO. Without an external antenna the WiFi signal tends to be too poor to be of any use over longer distances and/or through several walls. The board will have to modified slightly to enable the external antenna.
+
+![T7 pic](img/t7.jpg)
+
+Below you can see how to enable the external antenna. Move the zero ohm resistor from position 1-2 to position 3-4. Or remove the resistor and solder position 3-4 closed.
+
+![external-config](https://user-images.githubusercontent.com/17033305/78676790-34fd1080-78e7-11ea-8bb0-aee88efe75a6.jpg)
+
+See [this LilyGo issue](https://github.com/LilyGO/ESP32-MINI-32-V1.3/issues/4#issuecomment-610394847) about the external antenna.
+
+### Level shifter / inverter
+
+To invert and level shift the signal you can use a bc547 transistor with some resistors. For example like this:
+
+![invert-and-level-shift](https://willem.aandewiel.nl/wp-content/uploads/2019/04/DSMR_LevelShifter_Circuit-300x251.png)
+
+See [willem.aandewiel.nl/dsmr-logger-v4-slimme-meter-uitlezer/](https://willem.aandewiel.nl/index.php/2019/04/09/dsmr-logger-v4-slimme-meter-uitlezer/)
+
+### Some board variants
+
+![board no oled](img/board_no_oled.png)
+
+![board sh1106](img/board_sh1106.png)
+
+![board ssd1306](img/board_ssd1306.png)