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Topic: myDuino (my first PCB) (Read 2575 times) previous topic - next topic

glender

Hello Forum
---
I'm currently preparing for a little soldering-workshop with an Arduino-Board for soundgeneration. Because it would be too expensive for the attendees to buy a complete Arduino, I decided to build my first own PCB and give it to a productionline. 
Inspired by the work of several people I made my first Eagle Board and tried my best to have a board with the following attributes:

- All Power-Pins (8x) and all Output-/Input-Pins (27) fit for Breadboards (if needed)
- Minimal Arduino-Clone-Board with 16 MHz Crystal and Reset-Switch
- Mounting holes (bit small but still there)
- Smal dimension
- No FTDI (cheaper and not used for that Project)
- Two layers PCB
- Silkscreen on the front and back


Parts to Build the Board
---
1x ATMega 168P or ATMega 328P-PU
1x 16 MHz crystal (speed up the ATMega)
1x Voltage regulator 5V (volatage regulation)
1x 10uF capacitor (volatage regulation)
1x 0.1uF capacitor (volatage regulation)
1x 10k ohm resistor (reset-pin)   ---> or is it better to have a 1k ohm resistor here
2x 22pF capacitors (crystal)

(optional)
- Switch (reset)
- 28pin socket adaptor (swap ATMega)
- Header-Pins (swap cables)

Later I might design a "shield" with some LEDs and an FTDI on it. Do you see any problems with the current Design to add that later?

My design is based on the following Boards

- Boarduino (http://www.ladyada.net/make/boarduino/)
- Gorduino (http://thetransistor.com/projects/gorduino/)
- Project Board (http://www.kickstarter.com/projects/610437050/arduino-project-board)

My Board is also under CC-BY-SA (as marked on the board).

I kindly ask everyone to have a look at my board and check the files to see if I did a mistake. I hope I will get some inputs to publish a board witch is not only useful for me.

Thaks a lot!

Stefan Huber

joop

I would recommend placing the decoupling capacitor close to the ATMEGA's Vcc and ground. Maybe you can create some space between the crystal and D4.

glender

Hi joop
Thanks a lot for your answer! I realy aprshiat your help, because I'm a bit lost with this task...


I would recommend placing the decoupling capacitor close to the ATMEGA's Vcc and ground. Maybe you can create some space between the crystal and D4.


I'm not much of a hardware guy. Therefore I have to ask witch decoupling capacitor you are refering to. I guess (25-33.3% chance...) you mean the 0.1uF. Right? Just for my understanding: Is there a problem with my place, or is it just better to have a better filter-effect? And why is that so? Because it is already a bit close arround the cristal, maybe it would also help (a bit) to switch the 0.1uF capacitor and the 10k ohm resistor. It's not much, but maybe 10-15% closer.

Thanks again!



Chagrin

Ideally the decoupling capacitor (yes, the 0.1uF) should be as close to the IC's VDD/GND pins as possible. If you fail to do this then Grumpy Mike will jump into your thread and post a link to his (excellent) tutorial at http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html ;)

joop


glender


Ideally the decoupling capacitor (yes, the 0.1uF) should be as close to the IC's VDD/GND pins as possible. If you fail to do this then Grumpy Mike will jump into your thread and post a link to his (excellent) tutorial at http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html ;)


Hello Chargin
---
Thanks a lot for your link. Now you convinced me! I was out of office for the last two days and so I didn't had the time to find a better solution. But I will do that in the next few days. I'll post later my new Design. Thanks!

Stefan Huber

glender

OK. Now I've got a new revision. Thanks a lot for your support!
I fixed the problem with the the decoupling capacitor and I also deiced to add a FTDI-Connection.

Do you have other suggestions? I'm not sure with the new layout. Is the FTDI correct integrated?


Here is the new layout:
https://github.com/signalwerk/simpluino
(hit the «Downloads»-Button top left)

eddiea6987

is it me or are you missing a capacitor from the 7805s  common gnd and its output? i just looked at the picture i do not have eagle to look at the board file
I could print the Arduino logo on a box of cereal and sell it as "Arduin-O's"

spycatcher2k

Hi, I made a prototype board from your .brd file. It works fine - Looks good. I added a ground plain (to save etchant), but its good practice anyways. Also you can mount the data pin headers facing down and mount it on a breadboard.

Good luck
Drew.
http://www.uk-pcb.co.uk - My UK Based PCB Fab & Assembly Company
Design work undertaken
SMD & Thru-Hole assembly

glender

hi eddiea6987 and spycatcher2k
---
Thanks for your posts. In the last few days I changed the pcb with help from Robert Patterson. But I do not have a respond from the pcb-production till now. But I think it should work. I commited the current status right now to the github.

Main Changes:
- Update of the Readme-File
- Add a ground plane
- 22pF capacitors are closer to the crystal

Thanks guys. I hope I'll get my pcb's soon...

eddiea6987

nice, i recommend iteadstudio.com if you want to get your pcb's made they offer 5cm x 5cm 10pcbs for 9.99 , they also have options for color mask, such as white blue black etc... or if its single sided and your etching at home then photo resist is the way to go
I could print the Arduino logo on a box of cereal and sell it as "Arduin-O's"

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