What's more exciting than displaying your refrigerator and freezer temperature on a small OLED? Nothing.
Sending temperatures with two DS18B20s, using a WeMos D1 Mini to share with the Blynk app, and displaying on a small OLED. OLED is "I2C interface 0.96" OLED 128x64 display module" from eBay.
| Title | Include | Link | w/ IDE? |
|---|---|---|---|
| Adafruit_SSD1306 | Adafruit_SSD1306.h | https://github.com/adafruit/Adafruit_SSD1306 | No |
| Adafruit-GFX-Library | Adafruit_GFX.h | https://github.com/adafruit/Adafruit-GFX-Library | No |
| Wire | Wire.h | https://github.com/esp8266/Arduino | NO!‡ |
| SPI | SPI.h | https://github.com/esp8266/Arduino | NO!‡ |
| OneWire | OneWire.h | https://github.com/PaulStoffregen/OneWire | No |
| Arduino-Temperature-Control-Library | DallasTemperature.h | https://github.com/milesburton/Arduino-Temperature-Control-Library | No |
| ‡See lessons learned below. |
Many thanks to all of the people above. How to edit this.
###NodeMCU's ESP-12E (or any 8266-based board) versus the I2C OLED (w/ Arduino... not Lua)
It in fact was! I attached the display to the SDA/SCL pins on my Arduino Uno and she worked great with Adafruit's SSD1306/GFX library! That is, after I:
- Changed the I2C address from 0x3D to 0x3C. Therefore
display.begin(SSD1306_SWITCHCAPVCC, 0x3C); - As notified during my first unsuccessful compile, changed the comment in line 69-70 of Adafruit_SSD1306.h (
#define SSD1306_128_64) to include my OLED dimensions.
Almost a happy ending. Using the exact same code from the Uno for my ESP-12E, I couldn't get anything to display on the OLED. I then learned that unlike the Uno, the ESP8266 family (of which the NodeMCU/ESP-12E belongs) doesn't have defined "hardware-defined" SDA/SCL pins. They need to be defined in software. Therefore, lesson one:
- Add
Wire.begin(4, 5);as my first line in void setup()
This was a little tricky because the pinouts of the actual ESP8266 chip (the GPIO pins) don't correspond to the ESP-12E breakout pins (the D1, D2, D3, etc). For example, GPIO1 ≠ D1, GPIO5 ≠ D5, and this is true for every GPIO. It's a mix-up. Between locating some pinout diagrams that translated this for me, and trial-and-error running the LED blink example on various pins, I figured it out. So in my Wire.begin(4, 5); 4 is my SDA (that's GPIO4, but pin D1), and 5 is my SCL (that's GPIO5, but pin D2). Lordy.
Excited to have figured this out, I compiled... and... got an error: "Wire.h does not name a type." In other words, Wire.begin wasn't something in Wire.h. Gah. Oh but it was. Lesson #2:
- If you're switching between two different "groups" of boards in Arduino IDE's board manager (such as Arduino standard, and ESP8266-family), each one of those might have it's own includes that are named exactly the same, but are actually different.
So get this: Wire.begin(4, 5); wouldn't compile... said it didn't exist in Wire.h. In the IDE I went to Tools -> Board, and changed from Uno to ESP-12E. Then I deleted #include <Wire.h>, went to Sketch -> Include Library, and selected Wire again. #include <Wire.h> pasted itself into the code. Doesn't seem any different, eh? It was! It is! This time it pulled the Wire.h from the ESP8266/Arduino library. Hit compile and it worked! Whheee!
But the OLED still didn't. I just needed to learn to read.
I was hell-bent (especially after seeing other peoples' glowing, pride-filled examples) to make the "stock" Adafruit library work with this OLED on my ESP-12E. I had started this whole process using Adafruit's example sketch ssd1306_128x64i2c. After not too much more cursing I learned lesson #4:
- Change
#define OLED_RESET 4to#define OLED_RESET 0, or some number so it's not the same as whatever SDA/SLC you've picked!
This was just bad luck that the SDA/SLC pins I chose were defined as a reset in Adafruit's example sketch, but after changing it from 4 to 0, the OLED at last lit up on my ESP-12E.
FYI, all of this happened on Arduino IDE version 1.6.5.
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