Clock with retro display

HPDL-1414 clock

After having ported Contiki to the Launchpad, I was eager on doing something with it. I built this simple clock with a vintage HPDL-1414 “smart four-character 16-segment alphanumeric” display and a msp430g2553.



The soldered clock from above and bottom. There is a lot of solder flux residue, and lots of small black pieces of fabric from my bag, which lessens the appeal of the white solder mask. Quite nice though. Now I should make one that runs off batteries instead (the HPDL-1414 can run from 3 V but looks a bit more faint then). The eagle-eyed may notice the work-around
on the button. Turned out the Eagle footprint I made was wrong, connecting the wrong two legs.

Video bootup

This video shows the clock booting up and me setting the time.

The clock is really simple. It’s powered over USB, with an AMS1117-3.3 LDO linear voltage regulator that drops the input voltage to a handy 3.3 V for the msp430, but the HPDL-14144 still gets 5 V directly from the USB Vcc, to keep the display output nice and bright. Fortunately, the display is compatible with 3.3 V on the IOs. There is a button used for setting time, and a GPIO used for alarm (eg a vibrator) or as now, a LED that blinks every second.

The HPDL-1414 display has two pins for choosing what character position to set, and seven pins for choosing what character to set (in ASCII). Supply voltage 5 V but accepts 3 V logic level on the IOs. The characters are 2.85 mm tall red LED magnified with bubble plastic in front of them. This gives them a very characteristic look which is very beautiful. Here is the replacement part. Here is some information about them from vintage display enthusiasts.

When booting up, the clock goes into demo mode if the button is held for a while, then shows a splash scroller, and finally starts the clock. The clock works just like any other clock. Push the button to set the time, hours first, then minutes. The demo mode scrolls through all the possible characters and shows a nice spinner animation. The clock is running my Contiki 2.6 port to Launchpad, available on Github.

I’m considering using a vibration motor, similar to those used in mobile phones, to buzz every 20 minutes during work hours as a reminder for the 20-20-20 rule to battle eye fatigue. The rule says that you should every 20 minutes, look at something 20 feet (5-10 meters for us Imperial-units-impaired) away for 20 seconds. This is especially important for anyone working by a computer for long durations at a time.


The PCB is a small outline PCB manufactured at a Chinese fab via DFRobot. Ten pieces of 5*5 cm 2-sided PCB with white solder mask and black silk screen for ca 20$ including shipping. The boards were of pretty good quality. My only complaint apart from *ahem* “user error” (forgot to add the silk screen layer when producing the Gerbers) is that for footprints with small separation between tracks, such as the SOIC MCU pads, or the signal and power pads on the USB connector, they removed the solder mask between pads, increasing the risk of solder bridges. But, considering the resulting boards look good, are cheap, relatively fast (3-5 weeks, don’t remember), and actually work, I’m very happy. I designed the PCB, and the library parts needed, in Cadsoft Eagle. The boards seen above is a mix of four boards on a 5*5 surface: two clock boards, one CC2500 radio module breakout board, and a ULN2003A breakout board.

Video demo

This video shows the clock booting up to demo mode, then continuing to normal boot up.

4 Comments

  1. YC Chan
    Posted 2014-April-2 at 15:18 | Permalink

    Hi,

    I’m interested to buy the completed tiny clock that uses HPDL 1414 as showed in the demo clip.
    Please advise on how to buy it from you (or elsewhere) if possible.

    Thanks :)

    yC Chan

  2. Posted 2014-April-18 at 08:36 | Permalink

    Marcus,

    I love the clock! Your work encouraged me to buy a few of these HPDL-1414 units to experiment with. In the demo video, it looks like the text fades in and out. How did you implement this? Is it just alternating between blank and the displayed character like PWM? I’d love to see you publish the plans and source code if you are willing to share the design.

    Thanks,
    —Joey

  3. Posted 2014-June-4 at 20:15 | Permalink

    It’s not for sale as the time needed to accomodate is cost prohibitive :P, but I can send you all the design files and a binary. The msp430 in SOIC package can be sampled from TI, the display and other components found on ebay or aliexpress. The code is in the contiki-launchpad repo on github (examples/launchpad/clock). The PCB can be made dirt cheap on eg “dirt cheap dirty PCBs” (google it).

  4. Posted 2014-June-4 at 20:23 | Permalink

    Hi Joey,

    thanks! Yeah, the HPDL-1414′s are great :).

    It does fade, I do it through (a very slow) PWM, hence the flickering. It clears the display and writes out the same string at a 128Hz PWM rate (so the duty cycle granularity is really limited). It was a last-minute effort so didn’t put too much effort into it. The code is already published since ages, it’s in the repo under examples/launchpad/hpdl1414-clock/ and perhaps under platform/launchpad/dev/. Repo: https://github.com/msloth/contiki-launchpad

    Of course, the schematic/gerbers/etc can be shared as well, should prob put them up there but can email them to you instead. That would be faster :)
    //Marcus

One Trackback

  1. By A Tiny Clock with a Retro Display on 2014-January-8 at 22:00

    […] Contiki to his TI Launchpad platform, [Marcus] was eager to do something with it. He therefore built a simple clock with a vintage HPDL-1414 “smart four-character 16-segment alphanumeric display” and a […]

Post a Comment

Your email is never published nor shared.