Sunday, January 11, 2015

Horizontal mod for the HDSP clock

Making a proper enclosure for the HDSP clock is challenging, since it was designed specifically to stand on a phone charging dock. Inspired by DaveC's lay-flat version (he didn't send photos of the inside though), I put some thinking into how to easily convert the "stand up", vertical clock, to an "encasable" horizontal one. The main requirement is to place the display perpendicular to the board. This could be done using a right-angle header of some sort, as shown in the photo below.

With this easiest solution, as you see in the next photo, the board must be upside down for the display to show properly.

With a bit of more work, basically re-wiring the connections to the display on the adapter PCB (that holds the display), the whole device looks more appropriate, as shown in the next photo.

Which brings me to the subject of "display adapters". Although the HDSP clock was designed specifically for HDSP-2534, it can be easily converted to use similar "smart displays" but with a different pin configuration, as is HDSP-2133. (I got this particular one as a gift from MarkB. Thanks once again!)

So, to recap, if you have one of these 8-character parallel-interface HDSP smart displays, you can use it with the HDSP clock through pluggable display-adapters (shown in the photo below). Note that the code works without modifications.

Now back to enclosure. The HDSP clock board seems to fit perfectly (according the the datasheet) inside a Serpac A20 box. Even the screw holes in the box match empty spaces on the PCB, so holes for the mounting screws can be drilled properly.
How about the buttons?
  • long-stem buttons could be accessed through holes in the upper side of the box (ugly though);
  • the buttons can be mounted on the back panel of the box, connected with wires to the board;
  • a Bluetooth module can be added, thus eliminating the need for buttons altogether (requires code changes);
  • add remote control.
I plan to update this post, with photos, after I try what I "preached" above.

Update Feb 10, 2015
I created a "double bubble adapter", using two QDSP-6064 ("bubble") 7-segment LED displays, shown in the photo below.

The LED segments are driven by the shift register's parallel outputs and the 8 digits are multiplexed directly with the processor. All these 16 pins are available on the original connector for HDSP-2534 display.


  1. Leave the board upside down and use long-stem switches.
    The switches exit the bottom, just use small feet for clearance.

    1. True. That's the reason I did not solder the buttons :)
      I still have to order the box (Serpac A20) though. Hopefully this weekend.