Test bench with rotary encoder for Adafruit GFX version

The following basic configuration can be prepared in order to follow along with the examples provided with the library.

• About
• Parts List
• Schematic
• Breadboard
• Sketch
• Use

About

Test bench for Adafruit GFX version of library consists of 128x64 OLED display and rotary encoder with built-in button used to navigate through the menu.

Note that some displays used in combination with Adafruit GFX will require slight modification of example sketches: in addition to properly selected Adafruit GFX constructor it may be required to explicitly call display() method of Adafruit GFX library at the end of the loop() to draw image buffer on screen (as in this case).

Note that some examples may not work on Arduino UNO R3 and it might be required to use more powerful board with more memory (e.g. Arduino Zero as in this particular case). Compiling for some boards (e.g. SAMD based ones, like Arduino Zero) may require to disable support for AltSerialGraphicLCD version of GEM in config.h (it is disabled by default since GEM ver. 1.5).

Parts List

• Arduino compatible board with enough memory for reliable operation (e.g. Arduino Zero)
• Rotary encoder with built-in button (e.g.)
• 128x64 OLED display based on SH1106 chipset or compatible with I2C interface (e.g.)

Schematic

Schematic is simple. Three signal terminals of rotary encoder (two for rotation direction, one for button) are connected to the input pins of Arduino initilized with INPUT_PULLUP mode with internal pullup resistors activated (alternatively it is possible to connect terminals using external pullup 10kOhm resistors and INPUT mode). You may wish to implement additional debounce filtering to minify chances of false readings at the moment of button press (or try to increase value of the debounceDelay parameter during KeyDetector initialization).

Connect I2C signal lanes of the display to corresponding pins of Arduino. Connect power and ground as required by your display. In case of a particular display used in this example, it is powerd by 3.3V and is compatible with 5V logic, so it is possible to wire it directly to Arduino without the need for power/logic level shifting.

Breadboard

Connect channel A output (also called channel 1, CLK, etc.) of encoder to Arduino input pin 2, channel B output (also called channel 2, DT, etc.) to pin 3, first button output (usually called SW) to pin 4. Connect second button output (if present) and ground terminals of encoder to ground. Connect power terminal (if present) to 5V or 3.3V (depending on Arduino board being used).

Note that it may be required to swap channel terminals of encoder if direction of rotation is determined incorrectly.

Connect SDA pin of display to SDA pin of Arduino, SCK pin of display to SCL pin of Arduino. Provide power to display.

Use

This test bench is compatible with the rotary encoder based Adafruit GFX examples supplied with the GEM library (if not stated otherwise).

After compiling and uploading sketch to Arduino, wait while OLED screen boots and menu is being initialized and drawn to the screen. Then start rotating knob of the encoder and pressing its button to navigate and interact with the menu. The following control scheme is implemented.

Encoder	Key identifier	Action
Rotate CW	GEM_KEY_DOWN	Navigate down through the menu items list, select previous value of the digit/char of editable variable, or next option in select
Rotate CCW	GEM_KEY_UP	Navigate up through the menu items list, select next value of the digit/char of editable variable, or previous option in select
Rotate CW while pressed	GEM_KEY_RIGHT	Navigate through the link to another (child) menu page, select next digit/char of editable variable, execute code associated with button
Rotate CCW while pressed	GEM_KEY_LEFT	Navigate through the Back button to the previous menu page, select previous digit/char of editable variable
Short press	GEM_KEY_OK	Toggle bool menu item, enter edit mode of the associated non-bool variable, exit edit mode with saving the variable, execute code associated with button
Long press	GEM_KEY_CANCEL	Navigate to the previous (parent) menu page, exit edit mode without saving the variable, exit context loop if allowed within context's settings

See description of the specific example for details.