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HardFOC driver

ISF15ACP4 Driver

A C++20 driver for the NKK ISF15ACP4 SmartDisplay, a pushbutton with a 96 x 64 colour OLED in its keytop. It initialises the display's SSD1331 controller, draws text, shapes, images and animations, and reads the switch, on any MCU with SPI.

Quickstart API guide Source on GitHub

The driver has no platform code. You give it a small class that writes SPI bytes with the D/C and SS lines, sets the reset and supply-enable pins and reads the switch; it does the rest: the reset pulse, the controller's initialisation table, memory windows, colour conversion and the hardware drawing commands.

Frameless OLED pushbutton ISF15ACP4 NKK Switches (SmartDisplay)
Display
96 x 64 RGB passive-matrix OLED, 65,536 colours (RGB565), driver with 96 x 64 x 16-bit display RAM
Host interface
SPI, write only: SS, D/C, SCK, SDI; clock cycle 150 ns minimum (about 6.6 MHz)
Supplies
VDD 2.4 V to 3.5 V (logic), VCC 14 V to 16 V (OLED drive, 11 mA typical with all pixels on)
Switch
SPST normally open, 100 mA at 12 V DC, 2.0 N, 1.8 mm travel, 1,000,000 operations
Operating range
−20 °C to +70 °C; display life 50,000 h at 100 cd/m² with 40 % of pixels on
Driver mode
65k-colour mode; full frames from a CPU canvas, or the controller's line and rectangle commands

Datasheet (NKK)

What you get

  • One object per button. SmartDisplay<YourPort> owns the reset, the supply sequence and the SSD1331 initialisation. See API guide.
  • A canvas with text. GraphicsContext draws pixels, lines, rectangles, a 5 x 7 font and RGB565 images into a 12,288-byte frame that Present() uploads. See Graphics.
  • Hardware drawing. Lines, filled rectangles, window clear and scrolling run on the controller with a few command bytes each. See API guide.
  • Animations and a button helper. Animator runs a frame callback at a fixed rate; ButtonUI debounces the switch into press, click and long-press events. See Animations.
  • Zero-overhead portability. The port is a CRTP class: no virtual calls, no heap, no RTOS dependency. See Porting.
  • Tested without hardware. Host unit tests check the exact byte stream and pin sequence against a recording port. See Testing and CI.

Where to go next

  • Quickstart

    Wire the button, write the port, show text in about 15 lines.

  • Hardware

    Pins, the two supplies, SPI timing and the power sequence.

  • Architecture

    The three layers and what each one owns.

  • API guide

    Initialise, draw, set brightness, read the switch and handle errors.

  • Porting

    Implement the SPI interface for your MCU.

  • API reference

    Every class and member, generated from the headers.