| View previous topic :: View next topic |
| Author |
Message |
asmallri
Joined: 12 Aug 2004
Posts: 1666
Location: Perth, Australia
|
|
 Posted: Fri Apr 11, 2014 2:52 pm |
 |
|
| Ttelmah wrote: | | ..Laid out properly, the DS1307, is reliable. |
I agree however that is not the problem in this case. The layout, while not ideal, is unlikely to cause what you are seeing.
Are you absolutely positive the crystal you are using is 32768Hz and it supports a 12.5pF load?
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!
Last edited by asmallri on Fri Apr 11, 2014 2:56 pm; edited 1 time in total |
|
 |
asmallri
Joined: 12 Aug 2004
Posts: 1666
Location: Perth, Australia
|
|
| Posted: Fri Apr 11, 2014 2:54 pm |
|
|
The specific links in both cases point to a crystal designed for 6pF load - not 12.5pF required by the DS1307. However both offer 12.5pF variants.
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
|
|
newguy
Joined: 24 Jun 2004
Posts: 1938
|
|
| Posted: Fri Apr 11, 2014 3:21 pm |
|
|
| asmallri wrote: | | The specific links in both cases point to a crystal designed for 6pF load - not 12.5pF required by the DS1307. However both offer 12.5pF variants. |
The point of the post was only to show that there are 32.768 kHz crystals that aren't in the "standard" cylindrical radial can package, as a previous poster had implied don't exist. |
|
|
asmallri
Joined: 12 Aug 2004
Posts: 1666
Location: Perth, Australia
|
|
| Posted: Fri Apr 11, 2014 3:30 pm |
|
|
| newguy wrote: | | asmallri wrote: | | The specific links in both cases point to a crystal designed for 6pF load - not 12.5pF required by the DS1307. However both offer 12.5pF variants. |
The point of the post was only to show that there are 32.768 kHz crystals that aren't in the "standard" cylindrical radial can package, as a previous poster had implied don't exist. |
Sorry. I took your previous post comments literally.
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
|
|
ezflyr
Joined: 25 Oct 2010
Posts: 1019
Location: Tewksbury, MA
|
|
| Posted: Fri Apr 11, 2014 3:52 pm |
|
|
| newguy wrote: | | asmallri wrote: | | The specific links in both cases point to a crystal designed for 6pF load - not 12.5pF required by the DS1307. However both offer 12.5pF variants. |
The point of the post was only to show that there are 32.768 kHz crystals that aren't in the "standard" cylindrical radial can package, as a previous poster had implied don't exist. |
Hi newguy,
Uh, no...... Actually, I implied no such thing, and in fact stated exactly the opposite: "I'm not saying they don't exist, but every '32.768 KHz' crystal I've ever seen has come in a cylindrical style package." What I was *implying* is that the package shown in the layout is NOT common for that particular crystal type, that's all! If you want to play 'Gotcha', at least try to get the original posting correct!
John |
|
|
bkamen
Joined: 07 Jan 2004
Posts: 1619
Location: Central Illinois, USA
|
|
| Posted: Sat Apr 12, 2014 9:05 pm |
|
|
| ezflyr wrote: | Hi,
Are you sure that you are using the correct crystal? I'm not saying they don't exist, but every '32.768 KHz' crystal I've ever seen has come in a cylindrical style package. I just checked Digikey, and they don't sell anything else! I suppose you may have just placed a footprint you had on hand without attempting to match your physical crystal?
|
John,
I've done several designs with flat SMT (like 5mm x 3.2mm) sized 32.768KHz crystals.
There's other sizes out there..
-Ben
_________________
Dazed and confused? I don't think so. Just "plain lost" will do. :D |
|
|
40inD
Joined: 30 Jul 2007
Posts: 112
Location: Moscow, Russia
|
|
| Posted: Mon Apr 14, 2014 5:03 am |
|
|
I have replaced the crystal, and problem has gone.
BTW - HC-49 footprint was placed on pcb specially, for using of the crystal in this package. There is a opinion that devices in this package are more precise. But it was out of stock in the shop. |
|
|
|
FAQ 
Search
Register
Profile 
Log in to check your private messages 
Log in
