Saturday, August 30, 2014

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.


  1. All the pro-mini boards I've seen do not have any of pins on the right side by the reset button (SCL,SDA,VCC..., which specific model is that?

    1. Indeed, it seems that that specific pro-mini is a rarity these days. I found one for you on ebay:

    2. Ah, thanks. Also, i'm guessing one needs to have machined male headers on the arduino to mate with the female ones in the kit?

    3. Right, I usually include those male headers too, especially when I ship the pro-mini.