Digital clock project error - Page 1
Forum section: electronics / beginners

author: haygarth17
author_rank: Contributor
timestamp: July 11, 2024, 05:47:03 am
content: I did built with my grandsons a digital clock bought from AliExpress. This is product I bought:https://www.aliexpress.com/item/1005006658584103.html?spm=a2g0o.order_list.order_list_main.15.28a11802ENG6xdThe electric scheme and the display with error code is attached.I can change hour and minute, date as well, all the settings actually the issue is the clock will always display this weird CSCS code and doesn't remember any settings I set. The seconds dot doesn't flash as it should and the only thing I can see when out of settings screen is this CSCS error.Any help please.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: July 11, 2024, 08:11:01 am
content: This is a wild guess. I think the CSCS message is coming from the firmware and maybe means Clock Stopped. Check if the lithium cell powering the DC1302 real time clock chip is flat.

author: haygarth17
author_rank: Contributor
timestamp: July 11, 2024, 08:28:05 am
content: Thanks for suggestion.I did check the CR1220 battery. It has 3.2V, which should be OK.

author: mikerj
author_rank: Super Contributor
timestamp: July 11, 2024, 08:31:48 am
content: I'm pretty sure you have the third 7 segment display installed incorrectly, it needs to be upside down on these clock kits. However check the build instructions very carefully, they may have changed the design so this isn't needed.

author: haygarth17
author_rank: Contributor
timestamp: July 11, 2024, 08:44:10 am
content: I did installed it the same with the seller picture (see attachment) and the way I did see it done in a YouTube video for same item.Or maybe I don't understand what you mean by "third 7 segment display"

author: haygarth17
author_rank: Contributor
timestamp: July 11, 2024, 09:13:54 am
content: It might be something related with the clock, like Clock Stopped, because it is very weird the LEDs for seconds (the ones located in the middle of display) aren't blinking as they should. What should I check to see if clock does work?

author: wasedadoc
author_rank: Super Contributor
timestamp: July 11, 2024, 09:15:13 am
content: Quote from: mikerj on July 11, 2024, 08:31:48 amNot relevant. All four digits are in a single module.

author: haygarth17
author_rank: Contributor
timestamp: July 11, 2024, 09:18:57 am
content: QuoteYes, they are a single module.

author: wasedadoc
author_rank: Super Contributor
timestamp: July 11, 2024, 09:21:09 am
content: If you have a multimeter check the voltage at U2 pin 7. If close to either 0 or 5 that suggests the oscillator is not running.

author: haygarth17
author_rank: Contributor
timestamp: July 11, 2024, 09:45:19 am
content: QuoteI did check it in two cases:1. with external power ON: pin 8: 3.2V, pin 7:0.24V, pin 6:3.37V, pin 5: 0V, pin1:5.09V, pin 2:0.31V, pin 3:0.43V, p4: 0V2. without external power: pin 8: 3.2V, pin 7: 0V, pin 6: 0V, pin 5: 0V, pin1: 0V, pin 2:0.14V, pin 3:0.29V, p4: 0V

author: wasedadoc
author_rank: Super Contributor
timestamp: July 11, 2024, 09:57:57 am
content: Those voltages seem ok.

author: haygarth17
author_rank: Contributor
timestamp: July 11, 2024, 10:01:21 am
content: QuoteBelow is the PIN description I found on Google for U2.

author: ledtester
author_rank: Super Contributor
timestamp: July 11, 2024, 10:30:19 am
content: Here's an idea: remove the DS1302 and see what the clock does.

author: haygarth17
author_rank: Contributor
timestamp: July 11, 2024, 10:36:42 am
content: QuoteThanks. I did it and the CSCS message is still there.The only difference I see is I'm unable to enter the settings anymore. (The way you enter the settings is to keep both S1 and S2 button pressed for at least 3seconds)

author: m k
author_rank: Super Contributor
timestamp: July 11, 2024, 11:24:59 am
content: Looks like a mirrored and flipped G instead of C.https://www.eevblog.com/forum/beginners/completed-diy-kit-but-not-working/

author: wasedadoc
author_rank: Super Contributor
timestamp: July 11, 2024, 12:28:06 pm
content: https://www.analog.com/media/en/technical-documentation/data-sheets/ds1302.pdfRecommended crystal load capacitors are 6pF, not 22pF.Can you get the correct time and date while using the settings buttons?

author: mikerj
author_rank: Super Contributor
timestamp: July 11, 2024, 02:34:05 pm
content: Quote from: haygarth17 on July 11, 2024, 09:18:57 amOk the design has changed, the earlier versions of this kit used discrete modules and one had to be installed upside down.

author: Kim Christensen
author_rank: Super Contributor
timestamp: July 11, 2024, 02:56:50 pm
content: Check for solder bridges. Use a magnifier if your eyesight is dodgy.For example, this soldering looks a bit marginal. There may be other joints like it:

author: haygarth17
author_rank: Contributor
timestamp: July 11, 2024, 11:08:51 pm
content: QuoteYes, I can, but they are not saved. Once I move to time screen they are lost.

author: haygarth17
author_rank: Contributor
timestamp: July 11, 2024, 11:13:28 pm
content: Quote from: Kim Christensen on July 11, 2024, 02:56:50 pmI will check and refresh all soldering I have access to now. Many of them are covered by the display and that one I can not remove with the tools I have. More than this I'll try to change the oscillator and if all of this will not work maybe I'll buy another kit and do the work more careful.Thanks all for your inputs.

author: haygarth17
author_rank: Contributor
timestamp: July 12, 2024, 02:18:35 am
content: QuoteJust to let you guys know, I did change the oscillator and the error doesn't go away nor changes.As I mentioned I'll purchase another kit and hopefully that project will end well so my grandkids will be happy.Thanks.

author: haygarth17
author_rank: Contributor
timestamp: July 27, 2024, 07:21:21 am
content: Late Update.Just want to add an update to above discussed error. After few hours of investigation I found the issue just by browsing internet looking for "digital clock ds1302 stc15w404as circuit" and comparing with my actual circuit. I found that pin 5 on my DS1302 (named RST or CE in other descriptions) had 0V but it should have been connected to pin 9 (named P5.5/CMP+ on my attached scheme) on STC15W404AS and have 2.9V. So I did a hard connection between pin 5 and pin 9 and "voila" it started to work. It doesn't look very pretty now, because I didn't have required tools to remove the display, so I had to use a small wire for this connection.Happy it works now and my grandsons can install it in its box and enjoy!

author: retiredfeline
author_rank: Frequent Contributor
timestamp: July 27, 2024, 12:49:21 pm
content: So was it a missing trace on the PCB or a jumper wire that you were supposed to add but not documented in the instructions?

author: m k
author_rank: Super Contributor
timestamp: July 27, 2024, 05:30:24 pm
content: First pictures of earlier manual are without sockets.There a dedicated component side trace is clearly present.Internal pull down of active high CE and missing pull up is quite solid show stopper.

author: haygarth17
author_rank: Contributor
timestamp: July 27, 2024, 11:20:41 pm
content: Quote from: retiredfeline on July 27, 2024, 12:49:21 pmIt probably was simply a cold soldering done by me or my grandsons on the PCB. It's difficult to know because that side of PCB it is now covered by display. Remember, it was an educational project for my grandsons, so, cold soldering or other issues were expected.

author: floobydust
author_rank: Super Contributor
timestamp: July 27, 2024, 11:28:05 pm
content: Once that LED display is soldered in, you've poured the cement and cannot access solder joints underneath it. Good you got it working.A different chinese clock kit that was showing "NSNS" except when setting the time.https://www.eevblog.com/forum/beginners/completed-diy-kit-but-not-working

author: haygarth17
author_rank: Contributor
timestamp: July 27, 2024, 11:51:52 pm
content: Quote from: floobydust on July 27, 2024, 11:28:05 pmThanks for that information. Pretty much same circuit and error caused by Clock Stopped issue.