$2 Clock Kit

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  • jmg wrote: »
    David Betz wrote: »
    Here is the source code for the "4 bits clock". The comments are a bit hard for me to read.

    That's good. Where did you find that ?

    Looks quite close, but seems to drive DIG4 from P3.3, not P3.7 of the SCH ? - can you check your actual PCB layout ? I guess that makes Buzzer P3.7 ? (idles Hi)
    - ah, find a commented line google says is ; CLR P3.7; Alarm output

    Seems to be more DisAsm than original ASM, but I guess that's likely where it came from anyway - someone else's ASM... ;)

    Assembles to 662 bytes and shows 12:00 in the simulator, (P3.3 fixed) I'll leave it running.

    Have to figure out what the buttons mean...

    Now says 12:06, so seems we have a pulse.
    Attached is the HEX file.
    I got it from the eBay seller. I'll have to check the connections later. I'm now assembling my L-Star board.

  • erco wrote: »
    Related, I'll try to connect a power bank as a backup battery/base.
    Second that. Even though we have a supply of cheap IKEA CR2032 cells here at home for our Honda key fobs, I don't plan on inserting one in the six-digit clock. It's much better imho to back up the power supply with a 2S LiPO and a diode. Everything keeps running in an outage and the LiPO is rechargeable. Of course it doesn't need frequent recharging. The LiPO that backs up my main OCXO timebase gets recharged and balanced about every three years, and that is overkill. :)

  • This is what I ordered at $3.08
    https://www.ebay.com/itm/C51-6-Bits-Digital-Electronic-Clock-Electronic-Production-Suite-DIY-Kits/172546486230?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

    This is the pcb pic of the board I received. It's obviously a revised pcb (earlier/later unknown)
    clock-6digit.jpg
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  • Here is the underside for anyone wanting to trace the design
    clock-6digit-bottom.jpg
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  • jmgjmg Posts: 12,616
    edited April 8 Vote Up0Vote Down
    David Betz wrote: »
    I got it from the eBay seller. I'll have to check the connections later.
    PCB image posted appears to route P3.7 to Buzzer.
    I also find another PCB image, that routes P3.3 to Buzzer, & other small changes, so looks to be 2 PCB pinout choices there ?
    Probably pay to check all traces, & LED internal wiring too. Pulling pins low with an empty IC socket would light the DIG/SEG being tested.


    Can you check the Colon drive, inside the LED ?
    Circuit just labels 'DP' and the 4:1 MUX Clock LED (12 pins) internal data I found, MUXed one led dot on DIG3 and other on DIG4

    However, software seems to drive DP with pulsed low duty with all digits off (5th time slot), rather like a separate LED would be driven. Such active low is opposite of all other SEG drives.
    I think a 12 pin 4 DIG LED, needs to MUX the decimal point, can't see how independent LED drive can work ?

    Anyone who has built a working one, does the DP pulse at 1s cadence ?

  • ercoerco Posts: 19,320
    My repaired 6-digit clock runs but keeps terrible time, loses over a minute per hour. Apparently some damage was done when the chip overheated.

    Fully assembled 6-digit clock for sale! Best offer! :)
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • Erco,
    How do we make lemonade with that lemon? Lol
    Jim
  • jmgjmg Posts: 12,616
    erco wrote: »
    My repaired 6-digit clock runs but keeps terrible time, loses over a minute per hour. Apparently some damage was done when the chip overheated.
    Fully assembled 6-digit clock for sale! Best offer! :)

    It's unlikely any warmed chip fault would still work nearly that correctly.
    Can you ask for the software, and check the 12MHz really is 12MHz ? - tho 1min/hr is not any standard crystal either.
    eg the common 11.0592MHz would run ~5.104min slow.
  • erco wrote: »
    My repaired 6-digit clock runs but keeps terrible time, loses over a minute per hour. Apparently some damage was done when the chip overheated.

    Fully assembled 6-digit clock for sale! Best offer! :)
    The six-digit clock I have has a single adjustment button that relies on push dwell time to switch between adjustment modes. Since I broadcast my own time anyway, via both IR and FCC Part 15, the bold plan is to pick up those encoded time pulses each minute and (with a $1 PIC) quickly adjust the clock via simulated pushes of the single button. So as long as the clock can tic off another 59 seconds, the sync pulses will do the rest.

    (The PIC will be replaced with a stripped down version of the P1 just as soon as Parallax makes that chip available. :) )



  • ercoerco Posts: 19,320
    Way OT: Vintage mechanical car clocks are at least as interesting as these. A solenoid winds the mainspring every few minutes, and they would self-calibrate each time you set the time.

    http://www.oldcarsweekly.com/restoration/restoration-tips/putting_the_ticktock_back_in_your_old_car_clock

    clockPhoto3.jpg
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • jmgjmg Posts: 12,616
    erco wrote: »
    My repaired 6-digit clock runs but keeps terrible time, loses over a minute per hour. Apparently some damage was done when the chip overheated.

    On the topic of keeping time, the source code David posted above, has this somewhat cryptic line

    MOV TL0,#0C4H ;#0B5H;Data has been corrected too slow 5uS

    Problem is, Sim says their supplied value of 0C4H gives 0.999713s, not 1.0000s, - the 0B5H that looks to have been removed, looks more correct ?

    Meanwhile, I've INT buffered the decimal point drive, in my UpTimer code base, to give an exact 1.0000s flash, so that can be measured on a counter.

    Checking that 3600*0.999713 = 3598.9668 - hmm, so they are fixing close to exactly one second an hour ? I wonder if there is a hour-roll over bug this fixes ?

    1-1/0.999713 = -287ppm, seems rather high for any Crystal variation ? I've not seen any kits with resonators either ?

  • Anyone know what assembler I need to use to assemble the source code I posted for the 4 digit clock?
  • jmgjmg Posts: 12,616
    David Betz wrote: »
    Anyone know what assembler I need to use to assemble the source code I posted for the 4 digit clock?

    I use TSim51 from here http://turbo51studio.orgfree.com/downloads/tsim51-latest-setup.zip, but almost any 8051 Assembler should manage the code.

    Attached is the edited source, and project file, that attaches the Simulator LED display.
    As mentioned above, the DP I think may be suss...
  • David BetzDavid Betz Posts: 12,911
    edited April 13 Vote Up0Vote Down
    I got my 6 digit clock kit today. It went together really easily and works fine. My PCB looks exactly the same as Cluso's. I have to find the instructions though so I can figure out how to set it...
  • erco wrote: »
    My repaired 6-digit clock runs but keeps terrible time, loses over a minute per hour. Apparently some damage was done when the chip overheated.

    Fully assembled 6-digit clock for sale! Best offer! :)
    Seems odd that the chip overheating would make the clock run slow. Maybe it's just a bad clock design.

  • jmgjmg Posts: 12,616
    David Betz wrote: »
    I got my 6 digit clock kit today. It went together really easily and works fine. My PCB looks exactly the same as Cluso's. I have to find the instructions though so I can figure out how to set it...

    That improves your batting average :)

    Some instructions may be here ?
    https://www.ebay.com/itm/C51-6-Bits-Digital-Electronic-Clock-Electronic-Production-Suite-DIY-Kits/142653287164?hash=item2136cc6afc:g:pjoAAOSw241YU-5S

    You could always ask for the code for this one too ?

    David Betz wrote: »
    Seems odd that the chip overheating would make the clock run slow. Maybe it's just a bad clock design.
    Does seem strange, a large error, but too small for a bad crystal ? - does your 6 Digit clock time ok over 1 hr ?
    Getting a clean, jitter free, 1 second decimal point signal that can connect to a frequency counter seems a good way to check at least part of the timing-chain.
    I've done that to the UpTimer code, and could do that to the 4 digit Clock, once the DP action is confirmed.
  • David Betz wrote: »
    I got my 6 digit clock kit today. It went together really easily and works fine. My PCB looks exactly the same as Cluso's. I have to find the instructions though so I can figure out how to set it...
    That's encouraging. I would hate to waste my 3 bucks :)
    Hope to get the grandkids soldering ours in the next 2 weeks (school holidays)
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
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  • Cluso99 wrote: »
    David Betz wrote: »
    I got my 6 digit clock kit today. It went together really easily and works fine. My PCB looks exactly the same as Cluso's. I have to find the instructions though so I can figure out how to set it...
    That's encouraging. I would hate to waste my 3 bucks :)
    Hope to get the grandkids soldering ours in the next 2 weeks (school holidays)
    My kit came with a number of "spare parts". There were some extra resistors, capacitors, and LEDs.
  • Cluso99 wrote: »
    This is what I ordered at $3.08
    https://www.ebay.com/itm/C51-6-Bits-Digital-Electronic-Clock-Electronic-Production-Suite-DIY-Kits/172546486230?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

    This is the pcb pic of the board I received. It's obviously a revised pcb (earlier/later unknown)
    clock-6digit.jpg
    Any idea what J2 is for on this board? It seems to be the only thing connected to the 78L05 part. Is that a voltage regulator? Could J2 be a way to feed unregulated DC?

  • jmgjmg Posts: 12,616
    David Betz wrote: »
    .. It seems to be the only thing connected to the 78L05 part. Is that a voltage regulator? Could J2 be a way to feed unregulated DC?

    Yes, 78L05 is a 100mA regulator, not LDO or low current, but cheap....
    If J2 is on the Vcc side, it's likely a direct Vcc connection 3-6V (max)


  • ercoerco Posts: 19,320
    @David Betz:

    I got two of the same 4-digit clocks you have (square PCB), neither of mine worked either. Nothing displayed at all until I removed the upper silicon diode, which feeds into the battery backup connector. Both have 88:88 displayed now, anyway. Yank your upper 1N4007 diode and see what happens. Something hinky going on here.

    BTW, I Googled and found your post at https://www.eevblog.com/forum/chat/c51-4-bits-electronic-clock-kit/
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • jmgjmg Posts: 12,616
    erco wrote: »
    I got two of the same 4-digit clocks you have (square PCB), neither of mine worked either. Nothing displayed at all until I removed the upper silicon diode, which feeds into the battery backup connector. Both have 88:88 displayed now, anyway....
    The code David posted earlier, comes out of reset showing 12:00
    Is that 88:88 mux driven ? (ie are there the expected 25% drive pulses on the cathodes ?)
    The reset default of 2051 is Pin Hi, so to drive K low to light LEDs, needs some sort of code.

    Attached are 2 2051 hex files, one is from the code David posted, the other is a stopwatch type timer I found on the net, pin mapped to the 4-digit PCB.


  • Cluso99Cluso99 Posts: 14,236
    edited April 18 Vote Up0Vote Down
    J2 is connected across the speaker LS.

    So it's a speaker connection.
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  • Cluso99 wrote: »
    J2 is connected across the speaker LS.

    So it's a speaker connection.
    If that's the case it's interesting that it is marked + and -. Do speakers have polarity?
    erco wrote: »
    @David Betz:

    I got two of the same 4-digit clocks you have (square PCB), neither of mine worked either. Nothing displayed at all until I removed the upper silicon diode, which feeds into the battery backup connector. Both have 88:88 displayed now, anyway. Yank your upper 1N4007 diode and see what happens. Something hinky going on here.

    BTW, I Googled and found your post at https://www.eevblog.com/forum/chat/c51-4-bits-electronic-clock-kit/
    Well, at least I'm not the only one. I couldn't find anything wrong with my soldering. I ordered a second kit thinking that the MCU was defective on mine but it hasn't arrived yet.

  • TorTor Posts: 1,959
    edited April 18 Vote Up0Vote Down
    Speakers have polarity, but it only matters when you have two (or more) speakers.. you (or at least audiophiles) will connect them with the same phase.

    Edit: Maybe not just audiophiles.. it's been a long time since I connected speakers, but now I remember how I felt like I wanted to turn my head when listening to speakers connected with "opposite" (relative to each other) polarity.
  • Tor wrote: »
    Speakers have polarity, but it only matters when you have two (or more) speakers.. you (or at least audiophiles) will connect them with the same phase.
    Good point.

  • Having begun with electronics by constructing sound boxes and amplifiers, speakers polarity was one of the first things I'd learned (the first was "Except plastic knobs, never touch a tube amplifier without unpluging it from mains, specialy shiny metal parts under the chassis, and, even then, let it cool before handling it"). :o

    Easy peasy when you have to deal with subwoofers and woofers. Mid-range drivers and tweeters are not that easy, due to the subtle movements their cones will produce, when driven by a suitable dc source.

    https://youtube.com/watch?v=hjaR_RWly5U
  • YanomaniYanomani Posts: 698
    edited April 18 Vote Up0Vote Down
    Tor wrote: »
    Maybe not just audiophiles.. it's been a long time since I connected speakers, but now I remember how I felt like I wanted to turn my head when listening to speakers connected with "opposite" polarity.

    Sometimes, only your eyes and the whole body would feel testimony some infrasonic frequencies, for sure.

    https://youtube.com/watch?v=LlPVpV2VBOs
  • A naked-bones test set.

    Beyond 2:47, the up-raising infrasonic-beat reaches a not so annoying (it depends on individual perception) frequency scale.

    https://youtube.com/watch?v=keDy6_2DiLQ
  • ercoerco Posts: 19,320
    That's not a piezo speaker, it's a magnetic buzzer. Yes it is polarized and no it won't work if connected backwards.
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
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