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Topic: Very Small Arduino (Read 15832 times) previous topic - next topic

aalex_arduino

You have to connect extra capacitor as shown below......with restistor.

CrossRoads

@aalex_arduino ,
Your picture didn't make it - what are you referring to?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

fm

Hi,

I was just about to place an order to iTead Studio to have the PCBs of this response fabricated and thought that you chaps could be interested. Like Colaboy, I am working on a small home project where size is important. I wanted something that should be small (1"x1" - 25x25mm) on the final assembly, have a reset button and, while developing I wanted to have a serial interface, and ISP. So I ended up doing a 1"x1" - 25x25mm arduino like board, with a USB to serial and ISP break out. Hence the arduStamp was born.

The nice thing about the board is that there are only components on the top layer, so it will be simpler to assemble - thinking about ordering stencils for it - and also it can be soldered directly onto the main board as an "ardu-chip" (another little project I was working on).

Any way, here are some images of the PCB and the schematic:





If calculations are correct and if you decide to build it the BOM of:

  • a fully assembled arduStamp with no headers would be roughly 13 €

  • with no USB would be round about 7€ tops


Any way, if any of you are interested please let me know as I will surely will have a few to spare. If any one is interested I suppose that the spare PCBs can be sent out for an even 2€ lets say - posting abroad is remarkably expensive here in Europe.
I would also appreciate if you took a look at the schematic, just in case there is something odd/wrong, I had the intention to polish up the PCB a bit and place an order tomorrow.

I also have a question, regarding the "arduChip", do you know if iTead Studio does side pads around the border of the PCB, i.e. metallization on edge pads from the top layer to the bottom?
   

CrossRoads

I don't see a DTR to cap to reset - could make resets a  little tricky for you.

"do you know if iTead Studio does side pads around the border of the PCB, i.e. metallization on edge pads from the top layer to the bottom?"
Shoot them an e-mail and ask:

"pcb" <pcb@iteadstudio.com>

They do have these PCB design tips:
•Single design, no panelizing
•Drills line and long slot can't be accepted  <<< You might get called out on this.
•Minimum slot 1mm*1mm
•DRC compatible as rule file attached
•The PCB size is smallest rectangle that can accommodate PC

Eagle DRC rule file here - You can use it to check if your board meet our rule limitation.  << your pic's don't blow up, hard to tell if you will have problems here.

Eagle CAM file here - You can use it to generate the gerber files from Eagle
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

fm

Hi CrossRoad,

thanks for your comments and review. The DTR cap to reset is C2, this is placed by the first connector in the schematic, I do agree that it is not an obvious place to see it and after looking at the resolution of the images I posted, less so.

As for the DRU, I have the habit of going through fab houses specs and customize the DRU to match their capabilities. For hobby kind of stuff, I like to put a safety margin on top of what they claim they are capable off (it increases the yield of working PCBs substantially if you don't stress their capabilities). So unless it is really necessary I add a safety margin and don't try to go for the finer tracks unless it is necessary, for example, with iTead Studio I go for a 8mil track width and clearance, 0.35mm holes min, etc.

You are quite right about the drill lines, I will give it a shot and see if they don't push it back.

I will also send them an email regarding the solder around the edges. However, I am not holding my breath back for a response. They seam to have this nasty habit of ignoring emails that have questions out of the standard.

Here is a BOM for the PCB and larger images of both PCB and schematic

BOM

Qty   Value   Device   Reference   Digikey part
6   0.1uF   CAP0805   08055C104KAT2A   478-1395-1-ND
1   PTC   PTC2012   0ZCE0020FF2G   507-1517-1-ND
4   1K   RESISTOR   RNCP0805FTD1K00   RNCP0805FTD1K00CT
1   10K   RESISTOR   RNCP0805FTD10K0   RNCP0805FTD10K0CT
1   10uF   CPOL-EUR/2012-12R   F920J106MPA   493-2328-1-ND
1   16MHz   CERALOCK CSTCE   CSTCE16M0V53-R0   490-1198-1-ND
1   ATMEGA328P   ATMEGA168   ATMEGA328P-AU   ATMEGA328P-AU-ND
1   AVR_SPI_PRG_6PTH   AVR_SPI_PRG_6PTH      
1   FT232RLSSOP   FT232RLSSOP   FT232RL   768-1007-1-ND
2   LED3   LEDCHIPLED_0805   APHCM2012CGCK-F01   754-1094-1-ND   
1   MBR0520LT   MBR0520LT   MBR0520LT   MBR0520LCT-ND
1   B3U-1000P   SWT-B3U   B3U-1000P   SW1020CT-ND
1   USBSMD   USB-MINI-B   iTead Studio   
1   arduSTAMP   BOARD_INFOS+   iTead Studio   


Cheers
   

fm

Sorry for the inconvenience, larger files of the arduStamp.
   

fm

OK, 5 boards have gone, anyone else wants one?
I'll be placing the order to iTead Studio today.
   

bstott

I'd like 2 to 5 depending on your pricing and sending. It looks pretty fun and nicely laid out. If I'm not too late.

bstott2002 at yahoo.com

fm

Hi

bare-boards are going to be sent for 2€ each including post via regular snail mail.

Don't worry about being too late, after the first round I have ordered another 10. I am still waiting to see if the design meets iTeadStudio's production constraints - i.e. "drill lines", although the design has vias instead.
   

CrossRoads

If you're in the US, don't forget I have these  on order already. Lots 4 power pins, lots of grounds available for signal hookups.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

Mini-uino boards getting closer!  iteadstudio reports: 
"The comments for your order are: This is the shipment notification of your order. We have shipped your order by Register Air Mail"
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

fm

Great stuff CrossRoads remember to post pictures of the mini-uino when you get them. I am curious about the difference as to how long they take to ship to the EU and the US. So far, they haven't complaint about the drill lines on the arduStamp. On a different note, I sent them an email regarding their capability to wrap the metalization around pads on the edges of the PCB and so far, as foreseen, they have ignored the question.
   

Packhorse

If I build up a circuit like the one in the original post and run it off a single Li Ion battery with a 16mhz crystal what speed will it run at and should I make it run slower?

Can I do it with out the crystal and if so how?

There is nothing in my project that requires  speed or great accuracy in timing.
While saving power is very important as it will only be working a few hours at a time once or twice a month and asleep for the remaining time.

CrossRoads

It will run at 16 MHz. You might see odd behavior as the voltage went below ~3.8. While the battery is ~4.2V you'd be okay.
If you ran at 8 MHz off the battery directly (no regulator) you'd be fine as well.

There are ways to run off internal oscillator, have not tried myself.  I believe I've read that blank parts from the factory are set to run at 1 MHz internally.
Browse the 'playground' for an article on that.
You'd need an AVR ISP programmer to get a program in to start, such as
http://www.mdfly.com/index.php?main_page=product_info&cPath=5&products_id=415
http://www.nkcelectronics.com/pocket-avr-programmer.html
and connect to the MISO, MOSI, SCK, Reset, GND, +5V pins to program the new part.

What is your plan to wake up from sleep at the appropriate times?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

Well, maybe not on playground articles. Perhaps you write & post one when you are done.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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