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Topic: CoreSam3x - small format Due compatible (Read 7744 times) previous topic - next topic

bobcousins

Oct 30, 2014, 02:38 am Last Edit: Oct 30, 2014, 03:10 am by bobcousins
Hello everyone, who wants a smaller Due?

This project spawned from the MicroDue project, which appears to be dormant. I didn't want to reuse the "MicroDue" name, as that project may get revived, and anyway my version is a little different, so I am calling this "CoreSam3x".

My goal was to create a smaller Due retaining as many features as possible.
- Board is 2 layer 50x50mm max dimension to take advantage of cheap PCB service.
- Components are 0603 or larger, 0402 are two small for my DIY skills!
- self contained board, so can be programmed and run with just USB cable
- compatible with "Due" board target in Arduino IDE, no extra support required

There are also JTAG pins and 6 pins for serial programming header.

This is a DIY Open Hardware project, I am not planning to make a commercial offering, if anyone wants to make and sell it please go ahead! But please wait until the design is finalised :)


Features:
- all Due pins broken out
- 2 extra GPIO extra pins broken out
- Ethernet pins broken out
- Battery backup pins broken out
- JTAG pins broken out
- on board USB (OTG, ie. device or host)
- on board 3.3V regulator
- buttons for reset/erase
- LED!
- RTC crystal
- 0.1" pitch pins
- mounting lugs for M2.5
- dimensions : 2" by 1.6" (51x41mm) excluding mounting lugs

I'll be refining the layout over the next few days and will probably get a batch of 10 PCBs ordered next week. I'll have a few spare boards available if anyone is interested. I haven't done a BOM, I would guess component cost would be around £15 for 1-10 quantity.

The board is pretty much full, at a pinch could squeeze some more on. I'll push the design and gerbers to my github repo soon.

If you have any comments/suggestions please let me know!
Please ask questions in the forum so everyone can benefit. PM me for paid work.

JWScotSat

Hi,

I'd be VERY interested in a working version of this. How far away are you from completion? At a price point of £15 I'd be willing to take the punt but I'll obviously need the full layout to ensure pin numbers etc work correctly.

Also, I'm assuming you've dropped the 5v regulator that takes 9-15v?

From prototyping before, I can tell you that LEDs are extremely useful for debugging. Will you be able to include a power, pin13 LED and maybe a usb serial tx rx? I'm assuming your plan is to program the board through the native usb port? As opposed to having a secondary chip for usb serial?

Good luck! I'll be watching this thread closely,

JW

stratosfear


Add another interested person to the list.  I like the fact you broke out the RTC battery pins.  Is the AREF pin easily accessible, too?  I'd definitely need coordinates for the headers to embed this on a shield.

Jon

Palliser

Hello bobcousins and nice initiative besides Val's small-footprint Due.

http://forum.arduino.cc/index.php?PHPSESSID=s2ui0jt0hjim94lukn0ea7aka1&topic=233091.0

I have a similar mini-Due footprint pet project that I'd like to make time to do one of these days. Imho, your last goal aspect regarding compatibility with Due and Arduino IDE is one of the most important ones. I mention this given that in the past I've been able to program a bare SAM3X8E using bossac with a .bin file from Atmel Studio 6 via 'native' USB. It works OK, but to me, it is a very 'naive' way to program it having all that potencial (Due libraries and examples) in the Arduino IDE. It's just a thought and good luck with your CoreSam3X.

p    

bobcousins

#4
Oct 31, 2014, 11:49 pm Last Edit: Nov 01, 2014, 02:31 am by bobcousins
Thanks for your comments !

@JWScotSat I've managed to squeeze on another LED for 3.3V rail, there is already a LED for D13. Given the size, I couldn't fit a 5V regulator.

For programming, there are several options, JTAG, serial, USB. A 3.3V FTDI 6 pin connector will allow programming by serial, if the chip is erased via erase button. For full automatic programming, the TAIJIUINO Due programming board can be used http://www.elechouse.com/elechouse/index.php?main_page=product_info&cPath=72_73&products_id=2213

@stratosfear I've added an external AREF pin.

@Palliser I guess Val is busy with other stuff but maybe he will come back to it. I had a look around and couldn't find any similar "micro" designs for Due, they tend to be bigger rather than smaller. AVR has plenty of micro-nano-mini designs so I figured there was a niche to fill.

There is a smaller SAM3X chip, but it is still 100 pins, and I felt keeping close to Due compatibility was useful.

I've now managed to utilise all but 4 pins on the SAM3X. Two of those pins are for the External Bus Interface, which means I am very close to having the full EBI available, and I have an obvious place for 2 more pins, that seems like an opportunity too good to miss!

At this stage I am still in prototype phase, it may take a couple of iterations to iron out problems.

Please ask questions in the forum so everyone can benefit. PM me for paid work.

Palliser

Remember that the Arduino/Atmel team still cooking the Zero (48-pins SAMD21) with host capabilities. I also have ported a TFT LCD and camera libraries that use all the EBI pins. I think I am not the only one waiting for the Zero or a smaller Arduino SAM solution. Anyway at the end of the day I am very happy with the Arduino Due! Good luck with your prototyping.

p

bobcousins

#6
Nov 03, 2014, 01:22 am Last Edit: Nov 03, 2014, 01:24 am by bobcousins
I think the Zero could be a good addition, when it arrives!


I've sent gerbers off to Itead and uploaded Kicad design files to my repo at https://github.com/bobc/bobc_hardware/tree/master/CoreSam3x

I've also uploaded a BOM, component cost comes to just under £15 if you are building 10 off.

Image rendered with latest version of Kicad, which sadly is still severely broken (as is this forum!)



Please ask questions in the forum so everyone can benefit. PM me for paid work.

reha

Hi,
great .. it was the thing , I had been looking for a long time. many thanks for sharing.. reha

graynomad

Bob, I don't see any decoupling caps, are they on the reverse?


______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

bobcousins

Bob, I don't see any decoupling caps, are they on the reverse?
Yes, on reverse.

Here is top, bottom and schematic for reference.
Please ask questions in the forum so everyone can benefit. PM me for paid work.

graynomad

That be more like it :)

Nice project.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

bobcousins

Yes, I have a good feeling about this project :)

I've started thinking about a motherboard, with stuff like a 16MB RAM, parallel TFT and ethernet. I don't really want to reinvent the ATSAM3X-EK, but I am tempted to add the Wolfson codec and revive my music player project.
Please ask questions in the forum so everyone can benefit. PM me for paid work.

paperslammer

bobcousins,

This is great.  I have been looking around for a small footprint Due. 

I can't find where the SDA and SCL lines are broken out.  Which header are they on?  I'd like to modify your board and add some sensors using I2C.  Are you able to share the files you used to make the board?    I have been using Eagle.

Thanks



bobcousins

#13
Nov 05, 2014, 07:58 pm Last Edit: Nov 05, 2014, 07:58 pm by bobcousins
I can't find where the SDA and SCL lines are broken out.  Which header are they on?  I'd like to modify your board and add some sensors using I2C.  Are you able to share the files you used to make the board?    I have been using Eagle.
There are both I2C channels on pins 38 & 40, and 20 & 86. The attached symbols show all pins available, I will create a better pin out diagram soon.

The design files are in Kicad (version BZR4022 or so) at https://github.com/bobc/bobc_hardware/tree/master/CoreSam3x

Please ask questions in the forum so everyone can benefit. PM me for paid work.

bobcousins

Here is a pinout diagram for current version :

CoreSam3x_pinout by donotdespisethesnake, on Flickr

The light blue labels are Arduino digital pin numbers, special functions are also named according to Arduino convention (e.g. RX1 is Arduino RX1).

Doing this I discovered I have missed off one Due pin, D73 which is one of the LEDs on the native USB. Possibly not too important, but for completeness I will probably swap bonus pin PB24 for PA21 (D73). I don't think PB24 is important, and I would like to keep the Port C pins for the EBI.

Just realised the SAM3X8E does not support SDRAM, so that nobbles the idea for a 16MB add on :( SRAM is supported though, and a 2MB static RAM is not too expensive. I guess even 1MB would be nice addition.

Does anyone have a need for NAND Flash?
Please ask questions in the forum so everyone can benefit. PM me for paid work.

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