Need quick review before board house

Fixing to send this to the board house Anything should change/correct?

Thanks guys ;)

Could be tough to slide the battery in when a screw is in that mounting hole.

Pads are often at or below the solder mask level. Battery holder manufacturers typically recommend clearing out the solder mask larger than the contact surface of the battery, to ensure the pad is the highest feature and makes good contact.

Just out of curiosity, why are you sending that to a fab house? You could totally etch that yourself.

Or are you selling this as a product?

My only comment would be about the 'hardwired' I2C pull-up resistors. Many people use multiple I2C devices in a daisy chain arrangement and it would be better IMO to have jumper clips so one could disable the pull-ups if they wished to have the pull-ups located on a different board in the daisy chain. Just food for thought.

PS: Are you not also missing a ground connection to the external interface connect pads on the far right side of the board?

Lefty

I could etch my own with a smt 3v cell holder. Reason why I wanted to make a good pro board is bcause the breakouts currently in my mind are too much. Yes I could add a couple jumper pins as you stated and I did forget my ground connection (doh!)

I've got some questions about hardwired I2C pullups.

Are they necessary with the Arduino? I've heard people say that the Wire library activates the internal pullups.

I've heard people say that the Wire library activates the internal pullups.

I believe it does, and seems to work fine with a single close by device. However a stronger external pull-up is normally recommended according to spec and the number of devices on the net.

Lefty

I believe it does, and seems to work fine with a single close by device. However a stronger external pull-up is normally recommended according to spec and the number of devices on the net.

OK, thanks for the insight :).

Shouldn't pin 4 of DS1307 be connected to GND and pin 3 to Vbat (that is the + terminal of the battery)?

Shouldn't pin 4 of DS1307 be connected to GND and pin 3 to Vbat

It is. Coin cells are backward that way; the bigger terminal is B+ and the "button" is B-.

There is a lot of space left for a different arrangement of parts. I would use this to keep the traces to the crystal as short as possible.

Udo

I'll do some changing tonight and repost a photo. I'll add in jumpers and make sure there is a ground connection. I might have to do some top layer traces in order to achieve this..

R1 & R2 look huge to me. There is no reason to make them smaller but with a bit of juggling, this circuit looks ideal for a stripboard layout.

I finished with jumpers and some reason I can't seem to make a full pad on the holder it keeps the mask in the middle still...

Edit: New board

for this size of board you can easily use only 1 mounting screw

I’m a big fan of thicker traces when they’ll fit…

The pads on your resistors look particularly small; you might want to play with the DRC parameters (“Restring” if this is EAGLE.) You could go to smaller resistor packages as well (1/8 W resistor, or just closer lead spacing.

I would run SCL and SDA straight from connector to chip, with the pullup traces wiggling around as necessary…

You’re paying a big price for those jumpers, both in board space and … in the cost of the jumpers themselves (and in their complexity.) I would have left it more like your original board with a “populate these resistors only if you need them.” But I guess it depends on the target customer…

Do you use a surface mount battery holder? if not, watch out for having copper on the right side to solder them to, I once made a design I etched myself and afterwards noticed that i had the contact pad and the pads for soldering the holder's legs to on the same side... glad I etched it myself ;)

Through hole mount. I could etch myself. I made pads thicker, made traces thicker. I think I'm happy with it. Now I got to make sure I get the files in order to send to board house and make sure they are correct. I'll have about 10 boards ;)

I would make the pads for the resistors larger, as the thermal expansion when soldering may pull smaller pads like the one's you've made free from the PCB.

I did so. I'll have few boards hopefully in couple weeks. Only prob is filling in the mask on the coin cell holder.