AVR-Chat

Chuck Hackett wrote:
>> From: Thomas Keller
>> ....
>>     
>>> The only thing I can think of is that the signal does not have enough swing
>>> above and below zero.  My scope shows Mark as about -2.75v and Space a abo+2.25vdc
>>>    This is probably not enough voltage swing for the RS-232 receivers in
>>> your PC port.  You might want to insert a TI75232 (MAX232 clone, much
>>> less expensive) in between your Butterfly and your PC.
>>>
>>>   I am expecting to have a Butterfly here soon myself, so i am looking
>>> forward to the same sort of fun you're havingm Chuck.

>>> Hi Tom,
>>>
>>> I was thinking that myself but I don't think I can get at the proper points on
>>> the Butterfly as it's multi-layer and SMD stuff that I don't have the equipment
>>> to get to.
>>>
>>>       

   Well, IIRC from the descriptions, all signals on the Butterfly can be 
brought out from pin headers.  I would assume this means the RS-232 
signals as well.

   As for powert, you'd probably be able to poiwer the device of the DTR 
pin on your notebooks RS-232 (it requres a 3.3 VDC Vcc, IIRC), nd iuts 
currtent draw should be low enough not to cause your RS232 drivers in 
yournotebook any headaches (of coursem there is a VERY good chance that 
the notebook is using 75232 or MAX232 chips as it is).
>>> But, since they advertise an RS-232 interface you'd think that it would work
>>> with a (fairly) modern laptop ... arrgggg ...
>>>       

   Doesn't the Butterfly sport a small "breadboarding" area?  It 
shouldn't take much room to interface to a MAX232 package.

tom

>>> I also tried it with a USB serial adapter that I have but no luck.
>>>
>>> Can a MAX chip be run from the power received from the laptop via DTR or
>>> something and driven by the "partially" level-shifted signal available from the
>>> Butterfly?
>>>
>>> By the silence on the list, I assume no-one has ever received data from the
>>> RS-232 interface on a Butterfly?
>>>