Pages: [1]   Go Down
Author Topic: Eagle - My first attempt is ready to go - I hope!  (Read 1667 times)
0 Members and 1 Guest are viewing this topic.
ottawa, canada
Offline Offline
God Member
*****
Karma: 6
Posts: 990
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I've been putzing at this thing forever and I think I'm ready to send it off to Seeed for fabrication.  It's an arduino clone with ttl serial interface along with a 4021 shift register and a 74c02 nor gate connected to a custom 30 pin interface to another microprocessor board.  The routing is a combination of auto-router and my efforts where I thought I could make a difference.  The ground and +V traces are 24 thou, the rest are 16. 

One specific question is whether I need ground polygons.  I'm tempted to leave them off because I figure I will have done *something* wrong and it will be easier to fix with just the working traces on the board.  Aside from the crystal there wouldn't be any very high frequencies on the board.  The  other processor is running at a few hundred khz.

The AVR is a dip but i used soic for the other chips because they're small and easy to solder.  The area at the left will be covered with a small chunk of proto board for connecting to the other micro at the 30 pin connector.  I stuck a small grid of pads and an extra soic pattern in there because there was room.

If anybody has any suggestions or observations I'd be grateful.  I'm going to print the gerber image off at actual size and lay out parts on it as another check before i commit.


* olduinoB.png (74.57 KB, 964x589 - viewed 49 times.)

* olduinosch.png (37.66 KB, 701x606 - viewed 34 times.)
Logged

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 538
Posts: 27089
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Add the top & bottom ground polygons. If you have to cut a trace and add a wire, the ground plane will not make a difference. You could lay the 7805 flat on the board than and use the ground planes to help cool it.
The design needs some more caps - on the VCC, AVCC, AREF, and 22 pf caps on the XTAL1 & XTAL2 pins.
I see an ICSP connector for downloading a bootloader, or a sketch that starts in place of a bootloader.
I see a serial interface if you want to download a sketch that way via the bootloader. The pinout used is not standard. You might want to revisit that so you plug on a standard part like an FTDI cable or an FTDI Basic. If you're planning on making your own adapter cable you're all set.
A Diode across the pullup resistor will make for more reliable downloads,
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

ottawa, canada
Offline Offline
God Member
*****
Karma: 6
Posts: 990
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Add the top & bottom ground polygons. If you have to cut a trace and add a wire, the ground plane will not make a difference. You could lay the 7805 flat on the board than and use the ground planes to help cool it.
The design needs some more caps - on the VCC, AVCC, AREF, and 22 pf caps on the XTAL1 & XTAL2 pins.
I see an ICSP connector for downloading a bootloader, or a sketch that starts in place of a bootloader.
I see a serial interface if you want to download a sketch that way via the bootloader. The pinout used is not standard. You might want to revisit that so you plug on a standard part like an FTDI cable or an FTDI Basic. If you're planning on making your own adapter cable you're all set.
A Diode across the pullup resistor will make for more reliable downloads,

Thanks very much for looking.  I'll add the polygons.  
I thought I had a cap on vcc but i'll add it.  The resonator has the caps built in I thought.
Holy cow if that serial cable layout is wrong that's a big oops - it's meant to be the same as my RBBB - i'll get right on that!

Thanks again

whew: I'm pretty sure the serial connector is ok - it matches my prototype which works with the same cable as my RBBB.  I guess it's not well labelled though - I'll add some clues for when I forget>
from top to bottom goes ground, skip, 5v, PC TX - AVR RX, PC RX - AVR TX, and RTS/RESET.
« Last Edit: June 22, 2012, 09:03:39 am by bill2009 » Logged

Greenville, IL
Offline Offline
Edison Member
*
Karma: 15
Posts: 1330
Warning Novice on board! 0 to 1 chance of errors!
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


 Is that a RS232 chip for serial conversion?  If so, usually there are some capacitors involved for it to work properly.
Logged


ottawa, canada
Offline Offline
God Member
*****
Karma: 6
Posts: 990
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


 Is that a RS232 chip for serial conversion?  If so, usually there are some capacitors involved for it to work properly.

The soic pattern in the bottom left is a spare spot for experimenting. 
Logged

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 538
Posts: 27089
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

No, the FTDI cable or FTDI Basic is a USB/TTL Serial adapter.
http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm  TTL-232R-5V
or
http://www.gravitech.us/arliandpropr.html
May need to cut a solder jumper, or add one (is designed to be changed) for 5V operation.

Folks are starting to use CP2102 modules from ebay as well, the kind that have DTR broken out. Cut the Reset trace and connect DTR to the same pin. May need to make an adapter cable to get all pins connected properly. I use crimp connector housings and crimp terminated wires from pololu.com to do that. Very handy stuff.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Pages: [1]   Go Up
Jump to: