Dynomotion

Group: DynoMotion Message: 1779 From: Troy Date: 9/9/2011
Subject: 3.3-5v conversion
Hello Tom

Maybee you can give me some advice on my breakout board.  I am designing a breakout board to translate the 3.3v signal pins on jp4 and jp6 to 5v.  I was hoping to use the maxim max3002 bidirectional level translator chip to do the level conversion (I have a couple of projects I want to use the kflop board for and I was hoping to make a single board without committing the pins to either input or outputs at this point.  The max chip seemed like it might be a way to do this.)

Anyways, I noticed in your writeup on step and direction setup that some of those pins have 150ohm pull down resistors, and I am trying to figure out a strategy to hook up my chip. I am no electrical engineer by any means, but I have designed and built many successful little assorted boards myself mostly arduino stuff, with an electrical engineer friend looking over my shoulder.  

My friend felt (without looking into my project to much) that the 150ohm pull downs would be a pretty strong pull down(do you agree), is there a way to turn off the pull downs or change there values?

Thanks for all your help.
Troy
Group: DynoMotion Message: 1780 From: Vlad O Date: 9/9/2011
Subject: Re: 3.3-5v conversion
Troy,
Look on break board solution:   http://umaxcnc.com
There is plenty of channels for strong noise protected conversion.
We have a few installations and it was successful.
Good luck.
Vlad


On Fri, Sep 9, 2011 at 12:39 PM, Troy <groups@...> wrote:
 

Hello Tom

Maybee you can give me some advice on my breakout board.  I am designing a breakout board to translate the 3.3v signal pins on jp4 and jp6 to 5v.  I was hoping to use the maxim max3002 bidirectional level translator chip to do the level conversion (I have a couple of projects I want to use the kflop board for and I was hoping to make a single board without committing the pins to either input or outputs at this point.  The max chip seemed like it might be a way to do this.)

Anyways, I noticed in your writeup on step and direction setup that some of those pins have 150ohm pull down resistors, and I am trying to figure out a strategy to hook up my chip. I am no electrical engineer by any means, but I have designed and built many successful little assorted boards myself mostly arduino stuff, with an electrical engineer friend looking over my shoulder.  

My friend felt (without looking into my project to much) that the 150ohm pull downs would be a pretty strong pull down(do you agree), is there a way to turn off the pull downs or change there values?

Thanks for all your help.
Troy
Group: DynoMotion Message: 1781 From: Tom Kerekes Date: 9/9/2011
Subject: Re: 3.3-5v conversion
Hi Troy,
 
Your friend is right those are strong pull downs.  We need strong termination to use that connector to do high-speed communication to our SnapAmp.  I don't think the Max3002 chip will drive those.  There isn't any way to disable those pull downs.  I can't think of a good/easy method to do what you are trying to do.  You might consider using some sort of multiplexing scheme instead.  For example for JP4 instead of having 10 bidirectional IO you could use 2 IO for control and create 8 inputs and 8 outputs on your board.  The disadvantage would be that you would need to execute a few instructions to read or write to the IO.
 
Regards
TK

--- On Fri, 9/9/11, Troy <groups@...> wrote:

From: Troy <groups@...>
Subject: [DynoMotion] 3.3-5v conversion
To: dynomotion@yahoogroups.com
Date: Friday, September 9, 2011, 9:39 AM

 
Hello Tom

Maybee you can give me some advice on my breakout board.  I am designing a breakout board to translate the 3.3v signal pins on jp4 and jp6 to 5v.  I was hoping to use the maxim max3002 bidirectional level translator chip to do the level conversion (I have a couple of projects I want to use the kflop board for and I was hoping to make a single board without committing the pins to either input or outputs at this point.  The max chip seemed like it might be a way to do this.)

Anyways, I noticed in your writeup on step and direction setup that some of those pins have 150ohm pull down resistors, and I am trying to figure out a strategy to hook up my chip. I am no electrical engineer by any means, but I have designed and built many successful little assorted boards myself mostly arduino stuff, with an electrical engineer friend looking over my shoulder.  

My friend felt (without looking into my project to much) that the 150ohm pull downs would be a pretty strong pull down(do you agree), is there a way to turn off the pull downs or change there values?

Thanks for all your help.
Troy
Group: DynoMotion Message: 1784 From: aaronkscott Date: 9/9/2011
Subject: Re: 3.3-5v conversion
You might try opto isolators instead. You would have to find a suitable optocoupler such as the 6N137S. I you need bidirectional then ACSL-6210-00RE might work. You will pay more for the higher frequency bidirectional optocouplers, versus unidirectional and <100Khz operating frequency.

--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Troy,
>  
> Your friend is right those are strong pull downs.  We need strong termination to use that connector to do high-speed communication to our SnapAmp.  I don't think the Max3002 chip will drive those.  There isn't any way to disable those pull downs.  I can't think of a good/easy method to do what you are trying to do.  You might consider using some sort of multiplexing scheme instead.  For example for JP4 instead of having 10 bidirectional IO you could use 2 IO for control and create 8 inputs and 8 outputs on your board.  The disadvantage would be that you would need to execute a few instructions to read or write to the IO.
>  
> Regards
> TK
>
> --- On Fri, 9/9/11, Troy <groups@...> wrote:
>
>
> From: Troy <groups@...>
> Subject: [DynoMotion] 3.3-5v conversion
> To: dynomotion@yahoogroups.com
> Date: Friday, September 9, 2011, 9:39 AM
>
>
>  
>
>
>
>
> Hello Tom
>
> Maybee you can give me some advice on my breakout board.  I am designing a breakout board to translate the 3.3v signal pins on jp4 and jp6 to 5v.  I was hoping to use the maxim max3002 bidirectional level translator chip to do the level conversion (I have a couple of projects I want to use the kflop board for and I was hoping to make a single board without committing the pins to either input or outputs at this point.  The max chip seemed like it might be a way to do this.)
>
> Anyways, I noticed in your writeup on step and direction setup that some of those pins have 150ohm pull down resistors, and I am trying to figure out a strategy to hook up my chip. I am no electrical engineer by any means, but I have designed and built many successful little assorted boards myself mostly arduino stuff, with an electrical engineer friend looking over my shoulder.  
>
> My friend felt (without looking into my project to much) that the 150ohm pull downs would be a pretty strong pull down(do you agree), is there a way to turn off the pull downs or change there values?
>
> Thanks for all your help.
> Troy
>