Saturday, August 30, 2014

ProMini clock shield with OLED display

Yet another ProMini clock shield kit, this time featuring a 128x64 I2C OLED display.

The kit can be purchased with or without the OLED display (I prefer you buy the OLED on your own, for example this excellent one from miker).

  US$30, includes OLED display, free shipping to North America

  US$16, OLED not included, free shipping to North America

The kit includes:
  • PCB
  • DS1307 SMD
  • 32kHz crystal
  • CR1220 coin battery
  • battery holder
  • optional: I2C 128x64 OLED display (blue or white)
  • tactile switch (2x)
  • resistor 10k (2x)
  • machined male pins

The PCB was designed to accommodate I2C OLED displays with the 4-pin header configured either as VCC-GND-SDA-SCL or as VCC-GND-SCL-SDA.

The OLED clock can also be powered from the same LiPo battery shield for ProMini, as used in the bubble clock. To minimize current consumption (beside disabling the ProMini on-board LEDs), the processor can be awaken from sleep at the push of the "hours" button (on D3).

Schematic and board layout are shown below.

The OLED clock could show the time in many different ways, including Pong mode (sketch adapted from miker), analog clock mode, digital clock mode (sample sketches to be provided soon).


  1. The 128x64 display will make a QR-code clock possible.
    I've been thinking about a QR-code mode on the wise clock, but its 32x16 display limits it to micro QR-codes (15x15). There are not many smart-phone apps that can handle the micro QR-codes, so I rejected the idea.

    1. Sounds like a great idea.
      I will send you a kit :)

  2. Hi Florin,
    If I buy your OLED clock kit, where do I find the sketch for it?


  3. This post ( talks about the latest OLED-clock sketch.
    The OLED I have may have issues showing the Pacman mode, for some still unknown issue. You can buy your own, bigger and better, OLED from ebay for about $20.
    Otherwise, just showing the time as HH:MM:SS is covered by the above-mentioned sketch (see photo in that post).