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Topic: RTC modules - who's is "best"? (Read 5 times) previous topic - next topic

macegr

Their kits - alas - as a wee bit cheaper than "yours".
Even with "multi-buy" from you, with the postage and all.

Please don't be upset.


Haha, I know what I'm charging, and what my "competitors" charge. Pretty sure I'm the next cheapest option for this type of product, at least. Also, they have the DS3232 with NVRAM, but I have the DS3231SN with the industrial temperature range. It's just a simple breakout board...I even have the design files open source, so I'm not going to be upset if someone else makes something similar and people buy it. I still get a lot of business from the USA because Futurlec typically has to ship from Thailand.
Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store

angusisthedevil

Try RS Components then.

The freight will be as much as the part though probably.

Riva

#12
Jul 16, 2012, 10:21 am Last Edit: Jul 16, 2012, 10:23 am by Riva Reason: 1
From personal experience I suggest you avoid DS1307 unless time accuracy is not important. I have one and it looses about 7.5 seconds per day. I could order different crystals in the DS1307 to try and improve accuracy but that means more hassle and cost.
I also have several DS3231 and they are a lot more accurate at less than drift 2 seconds per month. I can also tweak the drift if needed by adjusting the ageing offset register using software but 2 seconds per month is good enough for me. Plus they have a readable temperature.

The DS323x range are more expensive than DS130x but in my mind worth the extra cost. To build your own is easy enough but once you add up the cost of the individual bits (IC, Breakout board, Pins, battery holder & battery) you may as well buy the pre-built modules.

Back to the original question between Jaycar & Altronics I would personally choose the Jaycar (freetronics) module as it appears to use a DS3232. The Altronics (sparkfun) module looks to use the DS3234. The DS3232 is a 2 wire interface and the DS3234 is 3 wire so one pin saved on the arduino.

RandallR


From personal experience I suggest you avoid DS1307 unless time accuracy is not important. I have one and it looses about 7.5 seconds per day. ...
I also have several DS3231 and they are a lot more accurate at less than drift 2 seconds per month.

The DS323x range are more expensive than DS130x but in my mind worth the extra cost.


You get what you pay for.  10 times the price for 10 times the accuracy.

I haven't done it yet, but I am looking at handling the drift in software.  Add or subtract a second every few hours.

Riva

Quote
I haven't done it yet, but I am looking at handling the drift in software.  Add or subtract a second every few hours

That's what I had to do in the end though as the project was a word clock (tells time to nearest minute) I only bother to adjust once per day at midnight. Drift is approx 7.5 seconds per day so at midnight I read the time, add 8 seconds, wait 0.5 seconds and then write the time back.

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