Propeller on a breadboard

shimniok

I like being able to quickly breadboard an Arduino and would like to do the same for the Propeller -- the support components make this a little harder.

Solarbotics makes a pcb that sits on top of a 28-DIP AVR chip (The Ardweeny: http://www.solarbotics.com/products/kardw/). It uses 0.1" pin headers that you solder to the chip pins. It's really handy and makes for a small, standalone footprint.

So I got the hair-brained idea to do the same for a Propeller. (Maybe someone already did this but hey it's fun) I drafted up a schematic and board design using SMD components (except the xtal) and have some parts on order from Newark and Sparkfun. The initial design is for a built-in FTDI usb-serial adapter. If that doesn't work I guess I'll put a prop plug 4-pin header on it instead. But anyway...

Eagle files: http://code.google.com/p/prop-pack/

I'm entering exciting new electronics fab territory here... Will I be able to use iron+laser printer to make 0.016" traces at home? Is it really possible to do SMT reflow in an electric skillet? Tune in next time... Will post updates if I actually pull this off...

Here's the schematic and board:

LMK if you see any issues with the design...

Thanks,
Michael

idbruce

Shimniok

Take a peek on page 6 of this thread. Such a coinidence, I just posted there and then saw your thread. It applies to diy breadboards for the propeller proto board.

http://forums.parallax.com/showthread.php?124495-Fill-the-Big-Brain

Bruce

JonnyMac

I would suggest you add a pull-up to the SCL line. No, the Propeller doesn't need it, but if you want to connect another I2C device this takes care of the requirement (assuming you want to "play nice" per the I2C spec and not drive the SCL line high).

jazzed

I like your idea.

It would be great if you could put a solder-tail socket on the board to accept plugging in a DIP40 propeller. That might mean moving the crystal and reset button. The crystal would easily fit in the open space of the socket or the center rail of the socket could simply be snipped. The reset button might be optional or put on an extended pin 1 side PCB area - a 2 pin header could serve the same purpose with the same size PCB.

Good luck with this.

MagIO2

What exactly is the difference to the PropStick USB?

Dr_Acula

LMK if you see any issues with the design...

Looking pretty good. It may be worth putting in two bypass capacitors. 0.1uF. Put them as close as possible to the propeller power supply pins.

jazzed

A propstick USB has a Propeller. This does not.

Ya, Dr_A is right about those by-pass caps ... add one for the FTDI chip if you can. While you're at it, may as well add pads for a 10uf 10V tantalum cap for extra by-pass to make the over-clocker's happy. Since you have little room on the top side, put the caps on the bottom.

I've been looking at the FTDI stuff, and have decided to use board power for the VDDIO pin instead of 3V3OUT. That way the chip won't try to power your entire target breadboard when the target power is turned off. If you follow this method, you should add the board detect voltage divider for RESETn. Without the resistors the device may not auto-identify when connected. Look at the FT232RL spec.

laser-vector

looking nice!

what software are you using to layout your PCB design?

shimniok

Thanks for the input all! Great suggestions for the design. Keep 'em coming!

My main goals for this project were low price and a standalone Propeller that's easy breadboarded so I can do more Propeller-based projects.

@jazzed: thanks for the info on the FTDI / power issue. WIll check it out.

Regarding the solder tail socket -- I think I understand what you're saying. Will give that some thought. My plan was to use 20x1 0.1" pin headers pointing down so the board can sit on top of a D40, and then solder the pin header to the prop's pins, similar to the Ardweeny (which costs $10):



@MagIO2: Versus the propstick. Difference is primarily price. The stick is $80 (eek!!!) What I'm working on will be considerably less.

At this very initial stage, the PCB is around $5 / board (far less if I can fab it at home), all the components are around $15 plus $8 for the prop. If I dropped the FTDI chip and used a 4-pin prop plug header that'd be $6 less. I may yet go that route.

Of course there's shipping and handling fees but in addition to ordering several at once, maybe I can get some folks in my local robot clubs to go in with me to defray some of those costs, too.

Anyway thanks again for the comments, I really appreciate it!

EDIT: I'm using Eagle CAD for schematic and pcb layout.

shimniok

Here's an update with pads for a 10uF 0805 cap, as well as a pair of 0.1uF and 1uF caps at each power pin. I added the other 10k pullup for i2c but had to add a jumper wire to do it so's I can still etch this board at home to test.

I ditched the FTDI chip and added a Prop Plug header and Sparkfun FTDI breakout board header. I figure if anyone wanted to make this board or go in with me on one, they'd probably have (or could justify getting) one of those two programmers. Losing the FTDI, etc. makes the component cost cheaper and the board less crowded.

Sapieha

Hi.

Now it looks next as my one.

CPUModule

shimniok wrote: »

Here's an update with pads for a 10uF 0805 cap, as well as a pair of 0.1uF and 1uF caps at each power pin. I added the other 10k pullup for i2c but had to add a jumper wire to do it so's I can still etch this board at home to test.

I ditched the FTDI chip and added a Prop Plug header and Sparkfun FTDI breakout board header. I figure if anyone wanted to make this board or go in with me on one, they'd probably have (or could justify getting) one of those two programmers. Losing the FTDI, etc. makes the component cost cheaper and the board less crowded.

jazzed

You don't need a 1uf and 0.1uf cap on each power/ground pair. Just 1 cap per pair is enough. Also, SMD resistor arrays can be almost as small as an 805 and are easy to solder for pull ups.

I think the FTDI chip adds value; it is expensive, but worth the trouble. Since you're leaving it out, I think I'll make a board that has it

JonnyMac

What I'm working on will be considerably less.

Only if you place zero value on your time! <wink>

JasonDorie

I've been wanting to make a PropStick equivalent without the reset button (I really never use it in a finished project) and without the USB - just using a PropPlug instead. I have a couple of PropSticks, but I bought them as a Daily Deal at $40, and they're handy, but too expensive to leave in-place on a finished project. I like the ProtoBoards, but I wish they had a flavor with less Smile on them - I don't use the VGA, keyboard, or mouse connections, so they're just wasted space for me.

I like your 'backpack' idea. I'll be keeping an eye on this.

agimuhing

I would use stackable headers (like these http://www.sparkfun.com/products/10007 ) instead of directly soldering pins to the prop.

This would make replacing a fried chip easier and decrease the chance of damaging the prop's own pins

shimniok

Good comments, thanks all!

@JonnyMac: good point Well, at least the time spent is fun

@Sapieha: nice work on the pcbs! I may have to order one from ya What are you using to do pcb/circuit design and 3d rendering?

@jazzed: FTDI -- now you have me rethinking. It's really nice on the mbed to just plug in the USB and go. Maybe I'll make a version with FTDI later... or just wait for you to make yours. I'll reserve one now.

@agimuhing: that's a really good idea. For an $8 chip it's probably a good idea to be able to replace it easily. Plus, you can transfer the chip from breadboard to a custom PCB that includes the support components and other circuitry... I'll see if I can source 20-pin stackable headers...

I found last night that making 16 mil traces is actually trivially easy. I made a board for my Wii cam homebrew LIDAR using 0805 sized passives etc and used my brand new "Reflow Skillet" which was also surprisingly easy. I've finally entered the 90's. So, I think I'm all set to fab up this prop board. Whee

WBA Consulting

Nice backpack idea. I really wish there was a way to easily backpack a DIP40 chip without making it look hacked like the ardweeney. I have a stripped down Propstick type board design with plenty of fabs waiting to be populated, but I have only made up 4 so far and only tested one. Here's the thread I started on it when I was trying to develop a test setup for the boards. It's meant to be the basic needs for a full propeller circuit in a DIP40 format. I already have someone interested in using one in a project of theirs and I am trying to finish building 2 for him this week. I have a backpack design for it that includes a power circuit, FTDI/USB, and a micro-SD slot and it backpacks nicely because my module has pass through style headers allowing a top connection that can be removable if you use female header sockets on the backpack. I have a visio drawing of the full concept somewhere and I will post it when I get to it. It may give you some more ideas.

shimniok

@WBA Consulting -- NICE! I'll have to take a closer look at the thread to see about cost as I may want one of the boards

Well, I fabbed up the first prototype. Transfer and etch of the 16 mil traces was no problem at all. And the TSSOP chip worked. But I officially hate TSSOP and will switch to SOIC on future versions.

I stupidly put the EEPROM on upside down and fried it so now I have to order another.





I agree the Ardweeny looks hacked. Mine won't win any aesthetics contests either. My goal was bare bones, rapid, ultra-cheap prototyping.

Parts cost around $2.50 per board (ordering from Newark) + shipping. Haven't priced Digi-key (where you can get free shipping). Board, around $4.50 plus $10 per run for S&H thru BatchPCB. The board is still single layer so a home hobbyist could do their own and save some bucks.

I designed an all through-hole version which would be cheaper for most folks since they have a stockpile like me. And it would be more accessible to a home hobbyist. Maybe I should go that route.

I looked and looked for 20-pin stackable headers. No dice. If you find some, let me know.

Once I get my replacement EEPROM I get to actually verify that the thing works.

More later...

WBA Consulting

Excellent job on the board. I haven't done my own since high school but have been looking at buying the stuff to do some. Your post reminded me to dig up my concept drawing so here it is. The M44D40+ PCB is done (obviously from my other thread), but the backpack board is still just a concept. The extra width allows a secondary row of female headers for topside access to the I/O pins for jumper wires, etc. Both would be done if it weren't for that precious commodity called time.....

I am using Samtec headers for the module that have a standard 0.025" square post on top, but a smaller 0.018 round pin on the bottom so that it closely replicates a IC pin better for PCB sockets. The Samtec part number is TSW-120-26-G-S. They are hard to find because the drawing is a "TSW Series" drawing and since only lead style "26" has this custom pin, there is just a note calling out "Except: Style –26
(0,46) .018 DIA Tail". The female headers are typical. A "stacking" female header is simply a female header with a very long tail length. For example, SSW-120-04-G-S, is a female header with 0.584" long leads. With a board thickness of 0.062", you will have a .522" long lead to plug into a breadboard or another female header to continue the stack.

M. K. Borri

I took the liberty of doing something similar, only with no SMD parts (easier to solder) and a serial port (to talk to a gps, originally).

Only, I use Ultiboard. How do I convert the ewprj file into a sch?

Granz

I know that this is not exactly what you were looking for, but...

In the same way that you can build an Arduino on a breadboard (http://www.arduino.cc/en/Main/StandaloneAssembly), you can also build a Propeller system on a breadboard. A while ago, I downloaded a layout from www.topprop.net which showed a breadboarded Prop system. The domain is not registered now, and I cannot find to where it has been moved (if at all), but I did use it in a simple project of building a homebrew Propeller Education Kit. I uploaded my document to my server (files.granzeier.com/Downloads/A Simple Propeller Breadboard-Perfboard Layout - Homebrew PEK.doc) so that you can take a look at it. If you use a PropPlug, you can eliminate the MAX-232 and associated circuitry and replace them with a simple 4-pin male header. Put this onto a double- or triple-wide breadboard, and you can add lots of additional circuitry.

If there are any troubles with copyright, or any other rights, and the original authors request it, I will remove it from my server. Until then, I hope this helps.