WEMOS 4 DIGIT CAN NOT SEE RTC == dodgy solder, as usual

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4 months 3 weeks ago #12970 by limnidytis
Hello everyone, recently I built a four digit Wemos clock. The clock works well, except for one problem that I can't seem to solve. The problem is the clock never finds the RTC that's connected to the clock. I checked the voltage to the vcc and and battery at the RTC in the voltage are a correct, delivered to the correct pins. i also checked the ground is connect to the correct pin. The status page says clock not found.

I'll be happy to hear suggestions about how to fix the,clock.

thanks,

Johnny

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4 months 2 weeks ago #12971 by Ty_Eeberfest
I don't know if I can be of much assistance because I don't have a schematic of that particular clock here, nor do I have an actual clock. Ian's the only one I know of that has the schematics. Having said that...

What you described sounds to me like an issue with the I2C bus. That's the SDA and SCL signals which are pins 5 & 6 of the DS1307 IC.

Pin 5 on the 1307 (SDA) goes to Pin D2 on the Wemos. R7 serves as the pull-up.

Pin 6 on the 1307 (SCL) goes to Pin D1 on the Wemos. R6 serves as the pull-up.

R6 and R7 should be 10K.

All I can really tell you is to visually inspect the SDA and SCL traces, the solder joints at the pins mentioned above, the values of R6 and R7, and so on. Note that with the Wemos removed and the power turned on SDA and SCL should read +5V referenced to ground (because of the pull-ups).

If all that checks out then perhaps the DS1307 is bad though that is highly unlikely!

Look into it later when the dust is clearing off the crater.
The following user(s) said Thank You: limnidytis

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4 months 2 weeks ago #12972 by limnidytis
Thanks much for the info on pin and resistors; when I checked the pin 5/r7/d2 and pin6/r6/d1 circuits, one was open. After a little solder touch up, the clock boots up with all green led now.

I would like to add a motions sensor to the clock, but am a little unsure about how to go about adding the sensor. I plan on using one do the microwave devices — so
1. Does the orientation of the board matter:
2. Should I use some wires to attach the board the clock:
3. What is the best way to secure the board in the clock case?

An image of an installed board would be extremely helpful == -0- ==

Thanks again for you help,

Johnny

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4 months 2 weeks ago #12973 by Ty_Eeberfest
Sorry but I can't provide an image because I don't have an installed motion detector. What I have is a bare motion detector hanging from some wires, which probably isn't helpful.

The side of the microwave motion detector with the chip on it is the "hot" side that should face outward for best results.

The detector is not compatible with metal cases. If you have a wood or plastic case, great, you can mount it inside the case. If you have a metal case you;ll need to come up with a way to mount the detector outside the case somehow.

Connecting it up with wires is how it's done. Keep the wires as short as practicable but don't worry too much about this. Just don't leave big loops of excess wire and it should be fine. Wires like this:
SV1 - VCC to detector VIN
SV1 - GND to detector GND
SV1 - PIR to detector OUT
The other 2 pins (CDS and 3V3) on the detector are not used.

The detector pulls the OUT pin high for motion and low for no motion, therefore the PIR Pullup option in the clock settings should be left off.

I'd say mount it using the screw holes provided in the detector board. To be safe I'd probably use nylon screws (these detectors don't like metal near them) and some sort of non-metallic spacers (stand-offs) to keep the detector from being pressed right up against the case. Best to mount it on the front wall of the case if possible so it's "looking into the room". These detectors seem to be pretty omnidirectional though so which wall of the case you mount it on is not super critical.

Look into it later when the dust is clearing off the crater.

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