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).

ProMini clock shield with 7-segment bubble display

Update May 6, 2016: This kit is no longer offered until I get a new batch of QDSP-6064 displays (whose price seem to have jumped considerably).

This clock was designed as a ProMini shield. It comes as a mostly-SMD kit, based on DS1307 with battery backup and the QDSP-6064 7-segment LED "bubble" display.

The kit includes the following:
  • PCB
  • QDSP-6064
  • DS1307 SMD
  • 32kHz crystal
  • CR1220 coin battery
  • battery holder
  • 330 ohm resistor 0805 (8x)
  • tactile switch SMD (2x)
  • machined female pins

The assembled clock can be fitted with a LiPo battery shield for ProMini, as shown in this post (source code also provided there).
The current draw (measured at 20mA with an unmodified ProMini) can be minimized by removing the 2 LEDs on the ProMini board, as well as dimming the 7-segment bubble display through software (SevSeg library). One other way of maximizing the LiPo battery life cycle is by waking the clock from sleep mode at the press of the "minutes" button (on D2).

Schematic and board layout are shown below.

Back in "business"

Just returned from my vacation in Paris. Hotel de Crillon was closed for renovations, Ritz had limited availability also due to renovation, so I had to settle for The Peninsula ;)

Here are a few impressions and observations, while still fresh.
  • taxis only take cash; ride from the airport to Paris center is about 60 euro and takes about 50 minutes;
  • the lowest cost Starbucks coffee is twice as expensive as here, at about $4.5 (3 euro), but still a lot cheaper than the "cafe creme" at Les Deux Magots or Cafe de Flore;
  • cheques are still used for grocery shopping (!);
  • the fixed air conditioning units (installed outside the windows) are probably not allowed, since they would really spoil the beauty of the buildings; posters are also forbidden, though I saw some "pixel art" placed high (that is, hard to remove) on some buildings;

  • one can actually live on and retire from a job as waiter or hotel concierge;
  • tipping in restaurants or for services is not a habit;
  • selling padlocks around famous places is big business;
  • Lacoste has a "lab" which also makes beautiful bicycles (this may be of interest to Justin :)
  • great Star Wars animatronics in DisneyLand Paris;

  • charging stations for electric cars;
  • and finally, a (probably expensive) clock :)