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Topic: Project: Bus pirate isolator/level converter NEW VERSION PA2 (Read 7215 times) previous topic - next topic

Project: Bus pirate isolator/level converter NEW VERSION PA2

UPDATE 2013-09-23: New preliminary release
Update schematic and component placement released: [attachment=0]

Hi!

I love the principle around the bus pirate. We would love to use it proffesionally in our company, but its to fragile for that.

I have started an internally sponsored projekt to develop an isolator + levelconverter compatible with the bus pirate. Of cource everything (schematic, BOM list, gerber, pick-n-place file, manufacturing spec) will be released under CC-0 when i feel it is ready

I have now compleated the first draft and would love community review and feedback.

Some remarks
* I'm aiming for exactly the same form factor as the bus pirate, if this means it will not be hand solderable, though luck...Hopefully bigger components can be choosen when the layout starts
* The design is choosen to be I2C-compatible and with clockspeeds up to 1Mbps. Sniffer mode sould also work
* Best possible components to solve the different problems will be choosen. Of cource i will try to cost optimize, but not compromising function
* The net names are clickable to make it easier to navigare
* It is intended to work down to 1.8V

Best regards
Stefan
Svep Design Center AB

Re: Project: Bus pirate isolator/level converter version PA1

Reply #1
Hi Stefan;
  I see that this is your first post - welcome.

Google could not find "4929 buffer".
The NTUD3170NZ looks cool until you see the size SOT-963 1.0 x 1.0 mm - holy craps!!!

Could you not make this using  more standard and user friendly parts?
Maybe even PTH - so I could build one)

Why not use opto-isolators? - they make fast ones.
Also page 2 of the PDF is empty.

It looks very promising and useful - impossible to build though.

Mick M

Re: Project: Bus pirate isolator/level converter version PA1

Reply #2
The buffer is an ON Semiconductor MC74LCX07DTR2G at the moment

The very smalls part is mostly because i reuse parts in our company library to save time. If you know of a cheep dual channel N-mos with logic level gate below 1.8V please advice

Opto isolators are more bulky an expensive i think, an generally dont support I2C

Its not impossible to build, just challenging :) I can hand-solder everything, but you need a microscope :)

Page 2 only contain revision history, everything electrical is on page 1

Re: Project: Bus pirate isolator/level converter version PA1

Reply #3
Hi Stefan;
  I did a search for"bi-directional fet voltage translator", and "i2c opto-isolator".
I got quite a few results.
The ISO1540 at Mouser is $4.95.

The buffer just drives the LED's - so not critical.

I am always nervous plugging my little BP into a new circuit.
So I am very interested in your progress on this.

This is just a hobby for me now, so I am not up on the the latest parts.

You can hand solder a 1mm part with 4 wires on a side ?.
I live on coffee, so no.

Post a picture.

Mick M

Re: Project: Bus pirate isolator/level converter version PA1

Reply #4
Mick, a slight exaggeration there :-)  A SOT-963 is only three pins @ 0.35mm pitch on each side.  A bit nasty, but certainly doable with dragsoldering followed up by some solder wick as long as you have a stereo microscope so you can see what you're actually doing.


Re: Project: Bus pirate isolator/level converter version PA1

Reply #6
A good replacement for the NMOS might be FDY3000NZ. Cheap and a bit bigger

I2C and opto isolation is not trivial, this explains why: "Google for AN10364 from NXP"
Possible replacement is SI8600, but i think it will be more expensive in higher volumes (doesnt texas still have their generous sample program)?

Throuh hole components are out of the picture, since my version is intended for pick-and-place and a wave soldering step is very expensive. You are welcome to do a variant of your own with more solderable components

I would love some help finding alternative parts!

Best regards
Stefan
Svep Design Center AB

Re: Project: Bus pirate isolator/level converter version PA1

Reply #7
Don't know if this is of any use to you.

Re: Project: Bus pirate isolator/level converter NEW VERSION

Reply #8
First post updated with new release

Re: Project: Bus pirate isolator/level converter NEW VERSION

Reply #9
Hi all

Did you finished this project?

Is there any possibility to buy it? If not do you konw any other similar products.