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Topic: Does This DS1307 RTC Module Charge its Battery, Or Not? (Read 540 times) previous topic - next topic

Zapro

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(I wonder what the 2 resistors + 1 capacitor there do, I will try to find its diagram)
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The resistors are I2C pullups and the cap is the decoupling cap for the chips VCC supply.

// Per.

card5

The resistors are I2C pullups and the cap is the decoupling cap for the chips VCC supply.
Thanks!

wow, that's quite minimal.

The DS3231 is a fantastic chip, really no need for a module when using it.

But for me, I would buy it as a module, since it's not a Thru-Hole chip, but an SMD one.
I prefer Thru-Hole chips, since they are breadboard friendly,
and also since when I solder components, I don't really do SMD, as mentioned before..

Zapro

Well, not really fantastic. It's a dinosaur.

See, this chip is fantastic in every single matter: Micro Crystal RV-3028-C7

// Per.

card5

The resistors are I2C pullups
From what I remember, we need the 2 pull-up resistors once, for the whole I2C bus,
and not for each component/module on the bus..

So I wonder why they include the 2 I2C pull-ups in many modules.

They assume that the user does not know about the need for pull-ups on the bus?
(and that their module is the only one on the bus?)


What happens when you connect several modules, to the same I2C bus,
and each of them has the 2 pull-ups..
Is that problematic, or because the pull-up resistance is high, then we should not worry?

I2C is usually recommended with 4.7KΩ for its pull-ups,
so If you connect 4 modules that each has it's own 4.7KΩ resistors, you then get close to 1KΩ..

Zapro

From what I remember, we need the 2 pull-up resistors per the whole I2C bus, and not for each component on the bus,
so I wonder why they include it in many modules.
They assume that the user does not know about the need for pull-ups on the bus?
(and that their module is the only one on the bus?)
Exactly

Quote
What happens when you connect several modules, to the same I2C bus,
and each of them has the 2 pull-ups.. Is the problematic, or because the resistance is usually high, then we should not worry?
Usually it will work fine. I2C pullups have a good middle ground at arund 4k7 - I2C specs state anything between 1 and 10K will work. So you will have to have many modules before running into problems.

Remember, these modules are made for amateurs. More advanced users will know about this and they will probably remove the extra pullups if they find it vital.

// Per.

card5

I see.
Thank you.

If only they manufactured this chip in Thru-Hole too, I could simply buy the chip, and skip the modules..

Zapro

There is absolutely no market in a trough-hole chip.

That's why you won't find it.

// Per.

CrossRoads

#22
Jul 11, 2019, 11:25 pm Last Edit: Jul 11, 2019, 11:25 pm by CrossRoads
Mouser still carries DS1307 in DIP

https://www.mouser.com/ProductDetail/Maxim-Integrated/DS1307%2b?qs=sGAEpiMZZMsWkX3fPoxIPao0OKuDwxf4

(forum seems to add some extra characters at the start of the link, delete them).
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

srnet

If only they manufactured this chip in Thru-Hole too, I could simply buy the chip, and skip the modules..
Sad fact of life really.

There is a market for a lot of ICs in through hole format, but the market is probably just not big enough (in quantity terms) to make is worthwhile for the manufacturers to make the things
http://www.50dollarsat.info/
http://www.loratracker.uk/

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