Power boost from a UART

C

Conrad, Robert

Guest
I had a PIC (16F627) that is going to be transmitting to another PIC over a
4 wire setup using both PIC's UART's. The wire distance will be about 100
feet at most. What do I need to do in order to power the signal between the
two? Will the chip provide enough power or do I need a transistor?

I would prefer to not add more microchips if posible.
 
"Conrad, Robert" <robertc> wrote in message
news:vto42ul08h2ea2@corp.supernews.com...
I had a PIC (16F627) that is going to be transmitting to another PIC over
a
4 wire setup using both PIC's UART's. The wire distance will be about 100
feet at most. What do I need to do in order to power the signal between
the
two? Will the chip provide enough power or do I need a transistor?

I would prefer to not add more microchips if posible.

The question is more of frequency handling ability of the wire,
Click to expand...
than power loss. What baud rate do you plan to use?

--
*
| __O Thomas C. Sefranek WA1RHP@ARRL.net
|_-\<,_ Amateur Radio Operator: WA1RHP
(*)/ (*) Bicycle mobile on 145.41, 448.625 MHz

http://hamradio.cmcorp.com/inventory/Inventory.html
http://www.harvardrepeater.org
 
Likely 9600 or 19200. Baud isn't a huge issue as I will only be sending a
single byte at a time on both directions. I am just worried about the chip
being unable to drive against the resistance of the wire over the given
distances.


"Thomas C. Sefranek" <WA1RHP@ARRL.NET> wrote in message
news:usmdnR3jqZsfoUGiRVn-jg@comcast.com...
"Conrad, Robert" <robertc> wrote in message
news:vto42ul08h2ea2@corp.supernews.com...
I had a PIC (16F627) that is going to be transmitting to another PIC
over
a
4 wire setup using both PIC's UART's. The wire distance will be about
100
feet at most. What do I need to do in order to power the signal between
the
two? Will the chip provide enough power or do I need a transistor?

I would prefer to not add more microchips if posible.

The question is more of frequency handling ability of the wire,
than power loss. What baud rate do you plan to use?

--
*
| __O Thomas C. Sefranek WA1RHP@ARRL.net
|_-\<,_ Amateur Radio Operator: WA1RHP
(*)/ (*) Bicycle mobile on 145.41, 448.625 MHz

http://hamradio.cmcorp.com/inventory/Inventory.html
http://www.harvardrepeater.org
Click to expand...
 
"Conrad, Robert" <robertc> schreef in bericht
news:vto42ul08h2ea2@corp.supernews.com...
I had a PIC (16F627) that is going to be transmitting to another PIC over
a
4 wire setup using both PIC's UART's. The wire distance will be about 100
feet at most. What do I need to do in order to power the signal between
the
two? Will the chip provide enough power or do I need a transistor?

I would prefer to not add more microchips if posible.
Click to expand...
Robert,

Tose PIC output pins are not designed to drive a line. Nevertheless they're
often used to do so and often there's no harm done. But a 10ft is quite a
distance and will build up a relative high - mainly capacitive - load.
Although I do not expect this load to blow the PICs, I do not expect this to
be a reliable connection. Other problems may arise like noise- and ESD
susceptibility. The latter being able to blow the PICs very easily.
Lightning for instance may blow all electronics but chips that have pins
connected to lines are prime victims.

So to stay on the safe side I advise to use line drivers/receivers. For the
distance you need a MAX232 type will do perfectly but will require some
extra components but the chips. Differential drivers/receivers like MAX3462
are also very good or even better.

petrus.


---
Outgoing mail is certified Virus Free.
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A simple 30mA interface should be easy, cheap, and sufficient.
<als>


In article <ECnDb.157099$G77.28554@amsnews02.chello.com>, p.kralt@hccnet.nl says...
"Conrad, Robert" <robertc> schreef in bericht
news:vto42ul08h2ea2@corp.supernews.com...
I had a PIC (16F627) that is going to be transmitting to another PIC over
a
4 wire setup using both PIC's UART's. The wire distance will be about 100
feet at most. What do I need to do in order to power the signal between
the
two? Will the chip provide enough power or do I need a transistor?

I would prefer to not add more microchips if posible.



Robert,

Tose PIC output pins are not designed to drive a line. Nevertheless they're
often used to do so and often there's no harm done. But a 10ft is quite a
distance and will build up a relative high - mainly capacitive - load.
Although I do not expect this load to blow the PICs, I do not expect this to
be a reliable connection. Other problems may arise like noise- and ESD
susceptibility. The latter being able to blow the PICs very easily.
Lightning for instance may blow all electronics but chips that have pins
connected to lines are prime victims.

So to stay on the safe side I advise to use line drivers/receivers. For the
distance you need a MAX232 type will do perfectly but will require some
extra components but the chips. Differential drivers/receivers like MAX3462
are also very good or even better.

petrus.


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.547 / Virus Database: 340 - Release Date: 2-12-2003
Click to expand...
 
Yes, you DO need something to drive the line: 100ft of cable is qute a
capacitance, and could easily blow-up your PIC outputs.

There are many types of "proper" line-driver chips available (both
single-ended and balanced.... balanced is better, but will need 2 pairs of
wire, rather than 3 wires).

Another cheap option is to drive the line with something like an
open-collector comparator (with a pull-up resistor at the remote end).... Or
even just use a TL072 op-amp... you could set that to be either single-ended
or balanced.


Paul

"Conrad, Robert" <robertc> wrote in message
news:vto42ul08h2ea2@corp.supernews.com...
I had a PIC (16F627) that is going to be transmitting to another PIC over
a
4 wire setup using both PIC's UART's. The wire distance will be about 100
feet at most. What do I need to do in order to power the signal between
the
two? Will the chip provide enough power or do I need a transistor?

I would prefer to not add more microchips if posible.
Click to expand...
 
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