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Member since Mar 2020 • Last active Mar 2020
  • 1 conversations

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  • in Puck.js, Pixl.js and MDBT42
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    Unfortunately it looks like the adapter from that link is out of stock and may no longer be available... However, I did see this (even better IMO) one on Tindie:


    Powered by microUSB w/ 3V regulator & it even has handy contacts to hook up an ammeter. The same seller has a number of other cool gadgets in their Tindie store...

  • in Porting to new Devices
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    Sorry to revive an old thread, & I'm sure you're busy with Bangle, but you can mark me down as a "would buy" if you ever released a MDBT50Q breakout similar to the MDBT42Q one :) The improved RAM and TX make it interesting to me! I'd be double-chuffed if you managed to fit a little LiPo charger/PMIC on there too, even if it slightly increased the size/price - power management is always a pain.

  • Avatar for dandelany

    After making the handheld, I got distracted by discovering DL1414/DL2416 "intelligent" LED displays. These things are cool! Originally made by Litronix, HP and Siemens in the 1970s as 4-character 16-segment alphanumeric displays, their descendants are still being made today, in the same form factor with similar part numbers, as 4 x 5x7 LED matrix displays. What makes them "intelligent" is the fact that you write 7-bit ASCII character codes to them, rather than having to worry about scanning through individual segments and digits.

    My favorite thing about the 2416 display in particular is that it has the same pin row distance, and almost the same # of pins, as the Espruino MDBT42Q breakout - so you can attach the two directly! Okay not quite - I had to bend & re-route the display GND pin around the board with a bodge wire. Though not necessary, I also decided to bend the display's VCC pin to attach to the BAT voltage instead of 3v3, since the higher LiPo voltage gives the display a bit more brightness. All pretty easy, and you end up with a tiny computer + retro display (see photos)!

    I've been testing the displays (1980s? era NOS/reclaimed units from eBay, ~$20) using this simple Arduino library I found on Github: https://github.com/ontuo/DL2416-Arduino-­library - and it was pretty easy to port it to a Javascript module for use with Espruino. I'll clean up the code this week and publish it on my Github with an open license. I also want to write a "scroll" function for longer messages.

    The whole thing comes out so small that I should (theoretically) have no problem fitting it into a case with a couple of buttons (only a few GPIO pins left...) and making a little retro watch out of the thing. I'm still trying to figure out the best battery + power management arrangement, the little Adafruit Micro Lipo charger I'm using, while small, may be too bulky unless I snip off the JST connector. More to come...

    Wishing you all health and safety, and a good project to work on, during these weird times.

  • Avatar for dandelany

    Hi! I've been keeping myself busy playing with the MDBT42Q breakout - in particular, working on a few ideas for watches, clocks and other "ambient" data displays. The low power + flexible voltage regulator on the MDBT42Q breakout make it ideal for things like this. And being able to program it wirelessly is awesome!

    I already posted this first project in the "what you're working on" thread, but figured I'd start a new thread where I can keep my notes/questions/related projects together.

    My first iteration is this little handheld device using an MDBT42Q + a Sharp Memory LCD + a LiPo/charger and a few buttons. These Memory LCDs are great - super low power, but much faster refresh rates than e-ink are possible. I'd like to eventually make a DIY minimal smartwatch using one of these displays, but figured this was a good way to get started and learn how to use them. More info + build log on this Hackaday page.

    I really like having physical buttons on my watches instead of a touchscreen - though these metal tactile buttons from Adafruit are a little big to be side-mounted (and too clicky to be practical on a watch!) I'm ordering a few different types from Digikey to try for the next version.

    I'd also like to experiment to find the lowest-power way to keep the LCD running - it needs a pulse on one of its pins every ~1-10 seconds to keep a voltage bias from building up and causing burn-in. Currently this is done with a setInterval in the Espruino MemoryLCD library, but it may use less power to tick it using hardware, with a TPL5111 or similar low-power timer, rather than waking up the SoC.

    For the most part, things have been working seamlessly and it was a lot of fun to build. The main problem I've run into - though I haven't yet tried hard to solve - is the fact that it takes ~400ms to update my 144x168 memory LCD (LS013B7DH05). I have gotten at least 10-15 FPS with one of these using a Feather board + Arduino library, so I know they're capable of it. I'm guessing this comes from the fact that the MemoryLCD module calls spi.send once for every byte of the framebuffer, causing a lot of function-call overhead for each frame. I'll experiment with calling spi.send with an array containing the whole buffer, or maybe the whole row at least? Any reason why this won't work? Thanks!


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    I haven't made this mod myself (yet), but was considering it & also read the threads you link to above. I opened the board schematic/layout in Eagle & I think I've figured it out.

    The confusion is from the fact that there are two different things called D7 - the diode part name in the Eagle file is "D7", whereas the pad you're looking at is the GPIO pin called "D7", but they are actually unrelated.

    It appears to me that Diode D7 is meant to be soldered to the two pads on the left side of the board, near the D27 pin - see the attached photo. In Eagle, these two pads are connected, so "cut the trace" presumably means the trace directly underneath the area between these two pads (being extremely careful not to cut the nearby traces to D28-31).

    Hopefully Gordon can chime in and correct me if I'm wrong :)

    Edit to add: re: orientation, the part symbol in Eagle shows the cathode (-) pointing down (towards the row of D28-31 pins)

  • in Puck.js, Pixl.js and MDBT42
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    Thanks allObjects! And thanks Gordon, that's very kind, I'll email you.

    I have a Fitbit with a touchscreen which always makes me feel like I have fat fingers, so I think I'm gonna stick with physical switches :) I'll look into some mini ones like the Pico - seems like Digikey has a good selection. Still trying to decide if I can pull off a usable watch with off-the-shelf breakouts etc., or if I'm finally gonna have to bite the bullet and learn how to design a PCB....

  • in Puck.js, Pixl.js and MDBT42
    Avatar for dandelany

    Hi all! I've been working on a project to create a DIY smartwatch, and have started playing with a Puck and an Espruino MDBT42Q breakout - such neat little devices! I'm still working on designing something that will fit in a watch form-factor, but I recently used the MDBT42Q to put together this little self-contained handheld prototype so I can start hacking on it :)

    I wrote it up on this Hackaday page, more build logs to come! https://hackaday.io/project/170205-rubbl­e-watch

    Thanks, Gordon, for a great platform - Espruino really is a lot of fun.