| Author |
Message |
Dan
Guest
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 Posted:
Sat Feb 05, 2005 2:39 am Post subject:
using rs232 chips to link io ports |
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http://www.hampleman.com/rs232.htm
The bmp in the above link shows how I want to use (2) sp232a chips (similar
to MAX232) to connect 2 processor's I/O pins together so I don't have to
worry about burning out the io pins if they aren't configured as input or
outputs which has happened to me before. I did post a question to this
effect before and someone recommended using the 232 chips. I just want to
make sure it will work.
Dan
dansteely2001 at yahoo dot com
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Rob Gaddi
Guest
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| Posted:
Sat Feb 05, 2005 2:48 am Post subject:
Re: using rs232 chips to link io ports |
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Looks like it ought to, and at only about 20x the cost of series
resistors on each line.
Dan wrote:
| Quote: | http://www.hampleman.com/rs232.htm
The bmp in the above link shows how I want to use (2) sp232a chips (similar
to MAX232) to connect 2 processor's I/O pins together so I don't have to
worry about burning out the io pins if they aren't configured as input or
outputs which has happened to me before. I did post a question to this
effect before and someone recommended using the 232 chips. I just want to
make sure it will work.
Dan
dansteely2001 at yahoo dot com
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Roger Lascelles
Guest
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| Posted:
Sat Feb 05, 2005 5:52 am Post subject:
Re: using rs232 chips to link io ports |
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"Rob Gaddi" <rgaddi@bcm.YUMMYSPAMtmc.edu> wrote in message
news:cu0mtn$cn@gazette.corp.bcm.tmc.edu...
| Quote: | Looks like it ought to, and at only about 20x the cost of series
resistors on each line.
|
Dan
Rob is telling you to put 2K2 resistors between the pins of the two
processors and forget the interface chips.
Roger
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Dan
Guest
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| Posted:
Sat Feb 05, 2005 6:05 am Post subject:
Re: using rs232 chips to link io ports |
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Its just a 1-off and I don't want to take any chances.
Dan
"Roger Lascelles" <invalidl@invalid.invalid> wrote in message
news:36ig6hF52e1a9U1@individual.net...
| Quote: |
"Rob Gaddi" <rgaddi@bcm.YUMMYSPAMtmc.edu> wrote in message
news:cu0mtn$cn@gazette.corp.bcm.tmc.edu...
Looks like it ought to, and at only about 20x the cost of series
resistors on each line.
Dan
Rob is telling you to put 2K2 resistors between the pins of the two
processors and forget the interface chips.
Roger
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Dan
Guest
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| Posted:
Sat Feb 05, 2005 6:22 am Post subject:
Re: using rs232 chips to link io ports |
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Besides, I might have the 2 processors some distance from each other.
Wouldn't the higher voltage levels help in that case?
Dan
"Roger Lascelles" <invalidl@invalid.invalid> wrote in message
news:36ig6hF52e1a9U1@individual.net...
| Quote: |
"Rob Gaddi" <rgaddi@bcm.YUMMYSPAMtmc.edu> wrote in message
news:cu0mtn$cn@gazette.corp.bcm.tmc.edu...
Looks like it ought to, and at only about 20x the cost of series
resistors on each line.
Dan
Rob is telling you to put 2K2 resistors between the pins of the two
processors and forget the interface chips.
Roger
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hamilton
Guest
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| Posted:
Sun Feb 06, 2005 8:40 am Post subject:
Re: using rs232 chips to link io ports |
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Dan,
On my screen, the two processors are only less than an inch apart.
In you first message, no mention was make about distance.
What did you expect ???
Dan wrote:
| Quote: | Besides, I might have the 2 processors some distance from each other.
Wouldn't the higher voltage levels help in that case?
Dan
"Roger Lascelles" <invalidl@invalid.invalid> wrote in message
news:36ig6hF52e1a9U1@individual.net...
"Rob Gaddi" <rgaddi@bcm.YUMMYSPAMtmc.edu> wrote in message
news:cu0mtn$cn@gazette.corp.bcm.tmc.edu...
Looks like it ought to, and at only about 20x the cost of series
resistors on each line.
Dan
Rob is telling you to put 2K2 resistors between the pins of the two
processors and forget the interface chips.
Roger
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mike
Guest
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| Posted:
Sun Feb 06, 2005 7:18 pm Post subject:
Re: using rs232 chips to link io ports |
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Dan wrote:
| Quote: | Besides, I might have the 2 processors some distance from each other.
Wouldn't the higher voltage levels help in that case?
|
All depends on what you mean by "some distance".
IFF I were paranoid,
I'd put a transistor/fet with open collector and maybe some clamp diodes
on the source end and a pullup followed by a current limiting resistor
on the input end and maybe some clamp diodes. Another advantage to the
inverter is that you can use a UART internal to the chip to talk to
RS232 with the correct polarity.
For short distances, I'd just use the series resistor, but split it up
into two pieces, one on each end to give a small amount of protection
with shorts, overvoltage, static etc.
mike
| Quote: |
Dan
"Roger Lascelles" <invalidl@invalid.invalid> wrote in message
news:36ig6hF52e1a9U1@individual.net...
"Rob Gaddi" <rgaddi@bcm.YUMMYSPAMtmc.edu> wrote in message
news:cu0mtn$cn@gazette.corp.bcm.tmc.edu...
Looks like it ought to, and at only about 20x the cost of series
resistors on each line.
Dan
Rob is telling you to put 2K2 resistors between the pins of the two
processors and forget the interface chips.
Roger
|
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