Stamp to PC via Serial RF
Archiver
Posts: 46,084
Hi Rafe,
The stamp is "isolated" or "protected" by the ten kilohm
resistor in series with each port. For real RS232,
the Max232 chips are great. I use them all the time.
Russ
Original Message
From: Rafe <rafe00@e...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, October 17, 2001 1:57 PM
Subject: RE: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
| Thanks.
|
| I was not aware of the MAX232 chips. I think there is a solution there.
|
| But . . .
|
| I still don't understand why we can plug the stamp into a pc's serial port
| and into the transceiver, but we can't plug the transceiver into the pc
| serial port. The carrier boards for the stamps don't have MAX232 chips.
| What is protecting the stamps from the 10V pc serial connection? How is the
| output from the stamp serial connection lifted from 5V to 10V? Does this
| question make sense?
|
| Rafe
|
| >
Original Message
| > From: Rodent [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=upgrt6mQ0PW-lxk4QaHMBSAMsxzi6XNtBdBczK-khhY5q-RzDUady_Xkpopcuq3uAAKPZEFgQgzp]daweasel@s...[/url
| > Sent: Wednesday, October 17, 2001 10:40 AM
| > To: basicstamps@yahoogroups.com
| > Subject: Re: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
| >
| >
| > Look at the Maxim MAX232CPE chip -- this is the typical interface from
| > TTL-level RS232 to PC RS232 and vice-versa.
| >
| >
| >
Original Message
| >
| > > I am interested in creating a wireless serial connection from
| > my stamp to
| > a
| > > pc. I would like to send data both ways. I've been looking at
| > Parallax's
| > > transceiver (part number 27988), but the on-line description
| > has a warning
| > > about connecting to a pc serial port.
| > >
| > > What is the circuit needed to connect the unit to a pc? Are there any
| > > important issues a beginner might need to know about?
| > >
| > > Should I be looking at a completely different solution?
| >
| >
| >
| > To UNSUBSCRIBE, just send mail to:
| > basicstamps-unsubscribe@yahoogroups.com
| > from the same email address that you subscribed. Text in the
| > Subject and Body of the message will be ignored.
| >
| >
| > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
| >
| >
|
|
| To UNSUBSCRIBE, just send mail to:
| basicstamps-unsubscribe@yahoogroups.com
| from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
|
|
| Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
|
|
The stamp is "isolated" or "protected" by the ten kilohm
resistor in series with each port. For real RS232,
the Max232 chips are great. I use them all the time.
Russ
Original Message
From: Rafe <rafe00@e...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, October 17, 2001 1:57 PM
Subject: RE: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
| Thanks.
|
| I was not aware of the MAX232 chips. I think there is a solution there.
|
| But . . .
|
| I still don't understand why we can plug the stamp into a pc's serial port
| and into the transceiver, but we can't plug the transceiver into the pc
| serial port. The carrier boards for the stamps don't have MAX232 chips.
| What is protecting the stamps from the 10V pc serial connection? How is the
| output from the stamp serial connection lifted from 5V to 10V? Does this
| question make sense?
|
| Rafe
|
| >
Original Message
| > From: Rodent [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=upgrt6mQ0PW-lxk4QaHMBSAMsxzi6XNtBdBczK-khhY5q-RzDUady_Xkpopcuq3uAAKPZEFgQgzp]daweasel@s...[/url
| > Sent: Wednesday, October 17, 2001 10:40 AM
| > To: basicstamps@yahoogroups.com
| > Subject: Re: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
| >
| >
| > Look at the Maxim MAX232CPE chip -- this is the typical interface from
| > TTL-level RS232 to PC RS232 and vice-versa.
| >
| >
| >
Original Message
| >
| > > I am interested in creating a wireless serial connection from
| > my stamp to
| > a
| > > pc. I would like to send data both ways. I've been looking at
| > Parallax's
| > > transceiver (part number 27988), but the on-line description
| > has a warning
| > > about connecting to a pc serial port.
| > >
| > > What is the circuit needed to connect the unit to a pc? Are there any
| > > important issues a beginner might need to know about?
| > >
| > > Should I be looking at a completely different solution?
| >
| >
| >
| > To UNSUBSCRIBE, just send mail to:
| > basicstamps-unsubscribe@yahoogroups.com
| > from the same email address that you subscribed. Text in the
| > Subject and Body of the message will be ignored.
| >
| >
| > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
| >
| >
|
|
| To UNSUBSCRIBE, just send mail to:
| basicstamps-unsubscribe@yahoogroups.com
| from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
|
|
| Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
|
|
Comments
it may help.
Original Message
From: "Rafe" <rafe00@e...>
To: "Basicstamps@Yahoogroups. Com" <basicstamps@yahoogroups.com>
Sent: Wednesday, October 17, 2001 8:11 AM
Subject: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
> I am interested in creating a wireless serial connection from my stamp to
a
> pc. I would like to send data both ways. I've been looking at Parallax's
> transceiver (part number 27988), but the on-line description has a warning
> about connecting to a pc serial port.
>
> What is the circuit needed to connect the unit to a pc? Are there any
> important issues a beginner might need to know about?
>
> Should I be looking at a completely different solution?
>
> Rafe
>
>
> Link to Parallax's transceiver:
> http://www.parallaxinc.com/html_files/products/RF_Mods/27986-27991.asp
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
pc. I would like to send data both ways. I've been looking at Parallax's
transceiver (part number 27988), but the on-line description has a warning
about connecting to a pc serial port.
What is the circuit needed to connect the unit to a pc? Are there any
important issues a beginner might need to know about?
Should I be looking at a completely different solution?
Rafe
Link to Parallax's transceiver:
http://www.parallaxinc.com/html_files/products/RF_Mods/27986-27991.asp
If you want to use wireless you must go Stamp to Stamp. The "base" Stamp is
connected to the PC. PC/Stamp communication is via Hyperterminal. Works for
me.
Sid
Thanks for the info - now I have more questions.
How is the base stamp connected to the PC?
Why exactly do you need two Stamps?
Can a Stamp 1 be used on the base side and a Stamp 2 on the receiver side?
For now I plan on using VB code to read/write the serial port of the PC.
I've never used Hyperterminal, but it would probably help with debugging.
Rafe
>
Original Message
> From: Newzed@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=VA_JYKJgwYGlFgw4Vd1HjXBhD_dZwnz94N5aqxFEKhFNVpv0ErhIl9phpBsNaqaFzShkDFFSCaXS]Newzed@a...[/url
> Sent: Wednesday, October 17, 2001 7:47 AM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
>
>
> For RafeOO
>
> If you want to use wireless you must go Stamp to Stamp. The
> "base" Stamp is
> connected to the PC. PC/Stamp communication is via
> Hyperterminal. Works for
> me.
>
> Sid
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
rafe00@e... writes:
<< Thanks for the info - now I have more questions.
How is the base stamp connected to the PC?
Resp: Via serial cable.
Why exactly do you need two Stamps?
Resp: Because you can't connect the transceiver directly to the PC
Can a Stamp 1 be used on the base side and a Stamp 2 on the receiver side?
Resp: If you mean a BS1 and a BS2, yes, providing you can program the BS1
for the appropriate serin/serout commands. Don't know anything about the BS1
- never used it.
For now I plan on using VB code to read/write the serial port of the PC.
I've never used Hyperterminal, but it would probably help with debugging.
Resp: Hyperterminal is very easy to use. You must load both Stamps with the
proper code, then exit the Stamp editor before you open Hyperterminal. You
can't run the editor and Hyper at the same time since they both use the same
serial port. I use Hyper extensively with excellent results. No
modifications to the serial cable required and no additional parts needed.
Just plug and go.
Sid
>>
TTL-level RS232 to PC RS232 and vice-versa.
Original Message
> I am interested in creating a wireless serial connection from my stamp to
a
> pc. I would like to send data both ways. I've been looking at Parallax's
> transceiver (part number 27988), but the on-line description has a warning
> about connecting to a pc serial port.
>
> What is the circuit needed to connect the unit to a pc? Are there any
> important issues a beginner might need to know about?
>
> Should I be looking at a completely different solution?
I was not aware of the MAX232 chips. I think there is a solution there.
But . . .
I still don't understand why we can plug the stamp into a pc's serial port
and into the transceiver, but we can't plug the transceiver into the pc
serial port. The carrier boards for the stamps don't have MAX232 chips.
What is protecting the stamps from the 10V pc serial connection? How is the
output from the stamp serial connection lifted from 5V to 10V? Does this
question make sense?
Rafe
>
Original Message
> From: Rodent [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=gsOtyj_p8NoxoADr3Z2NhBYr33xZmYNsplK_Pa_mYLrshkWqC8J3XIQyK-FG0Ib9ZXJ-aZuP4AAV]daweasel@s...[/url
> Sent: Wednesday, October 17, 2001 10:40 AM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
>
>
> Look at the Maxim MAX232CPE chip -- this is the typical interface from
> TTL-level RS232 to PC RS232 and vice-versa.
>
>
>
Original Message
>
> > I am interested in creating a wireless serial connection from
> my stamp to
> a
> > pc. I would like to send data both ways. I've been looking at
> Parallax's
> > transceiver (part number 27988), but the on-line description
> has a warning
> > about connecting to a pc serial port.
> >
> > What is the circuit needed to connect the unit to a pc? Are there any
> > important issues a beginner might need to know about?
> >
> > Should I be looking at a completely different solution?
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
uncommon for simple devices to "agree" to use 0 and 5V to communicate even
though they use "RS-232" protocol. However, the PC will send +/- 12V or so.
Many PCs will recognize 0 and 5V even though that is not to the RS-232
letter of the law. However, the signal is then inverted. The Stamp has
commands to let you pick "true" or "inverted" signals so you can directly
feed most (but not all) RS-232 devices. Coming back the other way is a
problem. If you apply 12V to a Stamp pin, the protection diodes will short
it to ground and you won't like the results. However, since the Stamp can
change polarity, you can protect the Stamp with a 22K resistor as shown in
the manual. Say the Stamp clamps to 5.7V on the input. The resistor has to
drop 12-5.7=6.3V and through 22K that is 286uA so no big deal there.
The Stamp, of course, has the "programming port". It uses a different
arrangement than the MAX232. 5V is OK for most serial ports, but you really
need to go negative not just to zero. So what the Stamp does is "steals"
the -12V from the idle RS232 input and routes it to the output when it wants
to output -12V. This gives it a reliable +5/-12V output, but it has several
drawbacks. First, everything you send to the Stamp gets echoed back to you.
Second, you can't operate full duplex. The MAX232 uses a capacitive charge
pump to actually generate about +/- 8 to 10V (depends on load) and uses
that.
An easy way to experiment with the MAX232 is our RS-1 kit
(http://www.al-williams.com/awce/rs1.htm). You can use it with a breadboard
or you can leave the pins out and use it to wire a MAX232 to your project.
Regards,
Al Williams
AWC
* Floating point math for the Stamp, PIC, SX, or any microcontroller
http://www.al-williams.com/awce/pak1.htm
>
Original Message
> From: Rafe [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ZAc3j-AWAAtDG7xN4Wp3Tk7qTJ76PBQHU3PoAHRuDWwtBGnxZz6XiFhPE2mqHrsge7vyID4eR7o-__0]rafe00@e...[/url
> Sent: Wednesday, October 17, 2001 12:57 PM
> To: basicstamps@yahoogroups.com
> Subject: RE: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
>
>
> Thanks.
>
> I was not aware of the MAX232 chips. I think there is a solution there.
>
> But . . .
>
> I still don't understand why we can plug the stamp into a pc's serial port
> and into the transceiver, but we can't plug the transceiver into the pc
> serial port. The carrier boards for the stamps don't have MAX232 chips.
> What is protecting the stamps from the 10V pc serial connection?
> How is the
> output from the stamp serial connection lifted from 5V to 10V? Does this
> question make sense?
>
> Rafe
>
> >
Original Message
> > From: Rodent [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ozw2u4DdQVFw1U90jxxl-wqouos8buEmIDYSMXMsEd4zSzLrNJyaWjKCcNciLXTYkNqEP7bwfR5N9yir]daweasel@s...[/url
> > Sent: Wednesday, October 17, 2001 10:40 AM
> > To: basicstamps@yahoogroups.com
> > Subject: Re: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
> >
> >
> > Look at the Maxim MAX232CPE chip -- this is the typical interface from
> > TTL-level RS232 to PC RS232 and vice-versa.
> >
> >
> >
Original Message
> >
> > > I am interested in creating a wireless serial connection from
> > my stamp to
> > a
> > > pc. I would like to send data both ways. I've been looking at
> > Parallax's
> > > transceiver (part number 27988), but the on-line description
> > has a warning
> > > about connecting to a pc serial port.
> > >
> > > What is the circuit needed to connect the unit to a pc? Are there any
> > > important issues a beginner might need to know about?
> > >
> > > Should I be looking at a completely different solution?
> >
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
> > Subject and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
> >
> >
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
Now for the ramblings of a non-engineer newbie . . .
I think my confusion was from having seen quick and dirty solutions were
someone was feeding the pc serial port 0 and 5V and everything was working.
I just could not quite remember how it worked and the more I thought about
it the more I thought that it shouldn't work that way. I bet there are a
lot of pc serial ports that will take 0 and 5V, but I am going to look into
a MAX232 solution.
I will look into a RS-1 circuit.
Thanks again everyone - this list is great.
Rafe
>
Original Message
> From: Al Williams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=PfYkcK537yLh79zUudFrbYmKNuo0gF4iGbry14y3sIFxF0Bzqyhjjl36q4MONfi_FkVmjSK1R9PCzO2MBKw]alw@a...[/url
> Sent: Wednesday, October 17, 2001 1:23 PM
> To: basicstamps@yahoogroups.com
> Subject: RE: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
>
>
> The Stamp can use any of its pins as RS-232 at TTL levels. So it is not
> uncommon for simple devices to "agree" to use 0 and 5V to communicate even
> though they use "RS-232" protocol. However, the PC will send +/-
> 12V or so.
> Many PCs will recognize 0 and 5V even though that is not to the RS-232
> letter of the law. However, the signal is then inverted. The Stamp has
> commands to let you pick "true" or "inverted" signals so you can directly
> feed most (but not all) RS-232 devices. Coming back the other way is a
> problem. If you apply 12V to a Stamp pin, the protection diodes will short
> it to ground and you won't like the results. However, since the Stamp can
> change polarity, you can protect the Stamp with a 22K resistor as shown in
> the manual. Say the Stamp clamps to 5.7V on the input. The resistor has to
> drop 12-5.7=6.3V and through 22K that is 286uA so no big deal there.
>
> The Stamp, of course, has the "programming port". It uses a different
> arrangement than the MAX232. 5V is OK for most serial ports, but
> you really
> need to go negative not just to zero. So what the Stamp does is "steals"
> the -12V from the idle RS232 input and routes it to the output
> when it wants
> to output -12V. This gives it a reliable +5/-12V output, but it
> has several
> drawbacks. First, everything you send to the Stamp gets echoed
> back to you.
> Second, you can't operate full duplex. The MAX232 uses a capacitive charge
> pump to actually generate about +/- 8 to 10V (depends on load) and uses
> that.
>
> An easy way to experiment with the MAX232 is our RS-1 kit
> (http://www.al-williams.com/awce/rs1.htm). You can use it with a
> breadboard
> or you can leave the pins out and use it to wire a MAX232 to your project.
>
> Regards,
>
> Al Williams
> AWC
> * Floating point math for the Stamp, PIC, SX, or any microcontroller
> http://www.al-williams.com/awce/pak1.htm
>
> >
Original Message
> > From: Rafe [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=erl4MJpnPInxMSa3OJS_BuA0ndHpaz-vURQGO1Lzp_D8QhVf2lChI6vUELsLtLwE2D82Nufvj2SX0vGIqAXC]rafe00@e...[/url
> > Sent: Wednesday, October 17, 2001 12:57 PM
> > To: basicstamps@yahoogroups.com
> > Subject: RE: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
> >
> >
> > Thanks.
> >
> > I was not aware of the MAX232 chips. I think there is a solution there.
> >
> > But . . .
> >
> > I still don't understand why we can plug the stamp into a pc's
> serial port
> > and into the transceiver, but we can't plug the transceiver into the pc
> > serial port. The carrier boards for the stamps don't have MAX232 chips.
> > What is protecting the stamps from the 10V pc serial connection?
> > How is the
> > output from the stamp serial connection lifted from 5V to 10V?
> Does this
> > question make sense?
> >
> > Rafe
> >
> > >
Original Message
> > > From: Rodent [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=8wHOaNtA7bp7EavsCrouX1jH9ZTT5gjVfhbD2TWFpaI5E_ppMTOIw5i23DC5cdEPpEOVWASNBcIU]daweasel@s...[/url
> > > Sent: Wednesday, October 17, 2001 10:40 AM
> > > To: basicstamps@yahoogroups.com
> > > Subject: Re: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
> > >
> > >
> > > Look at the Maxim MAX232CPE chip -- this is the typical interface from
> > > TTL-level RS232 to PC RS232 and vice-versa.
> > >
> > >
> > >
Original Message
> > >
> > > > I am interested in creating a wireless serial connection from
> > > my stamp to
> > > a
> > > > pc. I would like to send data both ways. I've been looking at
> > > Parallax's
> > > > transceiver (part number 27988), but the on-line description
> > > has a warning
> > > > about connecting to a pc serial port.
> > > >
> > > > What is the circuit needed to connect the unit to a pc?
> Are there any
> > > > important issues a beginner might need to know about?
> > > >
> > > > Should I be looking at a completely different solution?
> > >
> > >
> > >
> > > To UNSUBSCRIBE, just send mail to:
> > > basicstamps-unsubscribe@yahoogroups.com
> > > from the same email address that you subscribed. Text in the
> > > Subject and Body of the message will be ignored.
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> > >
> > >
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
> > Subject and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
>
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
to be capable of inversion. Think of it this way:
PC --> MAX232 (internal to PC) ----> MAX232 (external) ---> Device
(Of course, the PC might not have a MAX232 in it, but it has something -- a
1488/1489 pair, or something custom, or whatever).
If the PC sends a "1" the first invert flips it, then the second one flips
it back so the Device sees "1". If you remove just one of the MAX232's the
Device sees a "0" (inverted). With the Stamp that's not a problem since we
can control if it inverts serial data or not.
But if the device EXPECTS a MAX232 (or similar) inverter and has no way to
change its polarity then it won't work because everything is "upside down".
Remember, you can get rid of the internal "max232". So if your transciever
would work like this (and I'm not familar with them):
PC --> MAX232 --> MAX232 --> Transciever
It won't work if you remove one MAX232. That's OK for the Stamp, again,
because the Stamp can connect directly to it. So instead of:
Stamp -> MAX232 -> MAX232 -> Transciever
it is OK (to a point) to just do:
Stamp -> Transciever
because you are getting rid of both of them.
Whoops. I've gone on too long again :-)
Regards,
Al Williams
AWC
* 8 channels of PWM
http://www.al-williams.com/awce/pak5.htm
>
Original Message
> From: Rafe [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=g9bVFYgLarbrSPFvb24JtKjuGieKdC7hWhNAanlNLbHZeXOcoLz-WSV9Zi8aR4QgRHW7W2EdWENIit5W]rafe00@e...[/url
> Sent: Wednesday, October 17, 2001 2:15 PM
> To: basicstamps@yahoogroups.com
> Subject: RE: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
>
>
> Thanks for the long answer.
>
> Now for the ramblings of a non-engineer newbie . . .
>
> I think my confusion was from having seen quick and dirty solutions were
> someone was feeding the pc serial port 0 and 5V and everything
> was working.
> I just could not quite remember how it worked and the more I thought about
> it the more I thought that it shouldn't work that way. I bet there are a
> lot of pc serial ports that will take 0 and 5V, but I am going to
> look into
> a MAX232 solution.
>
> I will look into a RS-1 circuit.
>
> Thanks again everyone - this list is great.
>
> Rafe
>
> >
Original Message
> > From: Al Williams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=eX2uFsGtQGCiUmlZcPvMc1-JZS5NHMiiZJx4gJiy8w4mONQi-9nqIs8G1oZUE8glesWL-SyN2Jd7BmM]alw@a...[/url
> > Sent: Wednesday, October 17, 2001 1:23 PM
> > To: basicstamps@yahoogroups.com
> > Subject: RE: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
> >
> >
> > The Stamp can use any of its pins as RS-232 at TTL levels. So it is not
> > uncommon for simple devices to "agree" to use 0 and 5V to
> communicate even
> > though they use "RS-232" protocol. However, the PC will send +/-
> > 12V or so.
> > Many PCs will recognize 0 and 5V even though that is not to the RS-232
> > letter of the law. However, the signal is then inverted. The Stamp has
> > commands to let you pick "true" or "inverted" signals so you
> can directly
> > feed most (but not all) RS-232 devices. Coming back the other way is a
> > problem. If you apply 12V to a Stamp pin, the protection diodes
> will short
> > it to ground and you won't like the results. However, since the
> Stamp can
> > change polarity, you can protect the Stamp with a 22K resistor
> as shown in
> > the manual. Say the Stamp clamps to 5.7V on the input. The
> resistor has to
> > drop 12-5.7=6.3V and through 22K that is 286uA so no big deal there.
> >
> > The Stamp, of course, has the "programming port". It uses a different
> > arrangement than the MAX232. 5V is OK for most serial ports, but
> > you really
> > need to go negative not just to zero. So what the Stamp does is "steals"
> > the -12V from the idle RS232 input and routes it to the output
> > when it wants
> > to output -12V. This gives it a reliable +5/-12V output, but it
> > has several
> > drawbacks. First, everything you send to the Stamp gets echoed
> > back to you.
> > Second, you can't operate full duplex. The MAX232 uses a
> capacitive charge
> > pump to actually generate about +/- 8 to 10V (depends on load) and uses
> > that.
> >
> > An easy way to experiment with the MAX232 is our RS-1 kit
> > (http://www.al-williams.com/awce/rs1.htm). You can use it with a
> > breadboard
> > or you can leave the pins out and use it to wire a MAX232 to
> your project.
> >
> > Regards,
> >
> > Al Williams
> > AWC
> > * Floating point math for the Stamp, PIC, SX, or any microcontroller
> > http://www.al-williams.com/awce/pak1.htm
> >
> > >
Original Message
> > > From: Rafe [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=g9bVFYgLarbrSPFvb24JtKjuGieKdC7hWhNAanlNLbHZeXOcoLz-WSV9Zi8aR4QgRHW7W2EdWENIit5W]rafe00@e...[/url
> > > Sent: Wednesday, October 17, 2001 12:57 PM
> > > To: basicstamps@yahoogroups.com
> > > Subject: RE: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
> > >
> > >
> > > Thanks.
> > >
> > > I was not aware of the MAX232 chips. I think there is a
> solution there.
> > >
> > > But . . .
> > >
> > > I still don't understand why we can plug the stamp into a pc's
> > serial port
> > > and into the transceiver, but we can't plug the transceiver
> into the pc
> > > serial port. The carrier boards for the stamps don't have
> MAX232 chips.
> > > What is protecting the stamps from the 10V pc serial connection?
> > > How is the
> > > output from the stamp serial connection lifted from 5V to 10V?
> > Does this
> > > question make sense?
> > >
> > > Rafe
> > >
> > > >
Original Message
> > > > From: Rodent [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=l-tF5Ey1M5i_fsbMB-kuB7_bsNnwUaOrcbFuTmsoslzZWKI6kAAXMe0VHBub2awEyaObgRXPb7ur9Q]daweasel@s...[/url
> > > > Sent: Wednesday, October 17, 2001 10:40 AM
> > > > To: basicstamps@yahoogroups.com
> > > > Subject: Re: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
> > > >
> > > >
> > > > Look at the Maxim MAX232CPE chip -- this is the typical
> interface from
> > > > TTL-level RS232 to PC RS232 and vice-versa.
> > > >
> > > >
> > > >
Original Message
> > > >
> > > > > I am interested in creating a wireless serial connection from
> > > > my stamp to
> > > > a
> > > > > pc. I would like to send data both ways. I've been looking at
> > > > Parallax's
> > > > > transceiver (part number 27988), but the on-line description
> > > > has a warning
> > > > > about connecting to a pc serial port.
> > > > >
> > > > > What is the circuit needed to connect the unit to a pc?
> > Are there any
> > > > > important issues a beginner might need to know about?
> > > > >
> > > > > Should I be looking at a completely different solution?
> > > >
> > > >
> > > >
> > > > To UNSUBSCRIBE, just send mail to:
> > > > basicstamps-unsubscribe@yahoogroups.com
> > > > from the same email address that you subscribed. Text in the
> > > > Subject and Body of the message will be ignored.
> > > >
> > > >
> > > > Your use of Yahoo! Groups is subject to
> > > http://docs.yahoo.com/info/terms/
> > > >
> > > >
> > >
> > >
> > > To UNSUBSCRIBE, just send mail to:
> > > basicstamps-unsubscribe@yahoogroups.com
> > > from the same email address that you subscribed. Text in the
> > > Subject and Body of the message will be ignored.
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
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> >
>
>
> To UNSUBSCRIBE, just send mail to:
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>
> Remember, you can get rid of the internal "max232". So if your transciever
I meant, of course, ... you can't get rid of...
Regards,
Al Williams
AWC
* Control 8 servos at once
http://www.al-williams.com/awce/pak8.htm
done without a MAX232. You can even use pin 16 to talk to the PC through the
programming cable, but everything sent from the PC to the Stamp is echoed.
The MAX232 takes care of generating the proper voltages, etc... and allows
you to run a much longer cable.
I've used the cheapy AM 433 MHz transmitter and receiver to send data to a
PC from a Stamp -- on the PC end I used a MAX232. The only drawback is you
have to invert the signal to compensate for the MAX232 also inverting the
signal. I used a transistor, since I already had a circuit to drive an LED
to show when data was received. The MAX232 should only needed on the PC
end -- the radio modules probably work at TTL level and no conversion is
needed on the Stamp end.
Original Message
> I was not aware of the MAX232 chips. I think there is a solution there.
>
> But . . .
>
> I still don't understand why we can plug the stamp into a pc's serial port
> and into the transceiver, but we can't plug the transceiver into the pc
> serial port. The carrier boards for the stamps don't have MAX232 chips.
> What is protecting the stamps from the 10V pc serial connection? How is
the
> output from the stamp serial connection lifted from 5V to 10V? Does this
> question make sense?
>
> Rafe
>
> >
Original Message
> > Look at the Maxim MAX232CPE chip -- this is the typical interface from
> > TTL-level RS232 to PC RS232 and vice-versa.
> >
> >
> >
Original Message
> >
> > > I am interested in creating a wireless serial connection from
> > my stamp to
> > a
> > > pc. I would like to send data both ways. I've been looking at
> > Parallax's
> > > transceiver (part number 27988), but the on-line description
> > has a warning
> > > about connecting to a pc serial port.
> > >
> > > What is the circuit needed to connect the unit to a pc? Are there any
> > > important issues a beginner might need to know about?
> > >
> > > Should I be looking at a completely different solution?
>to a PC from a Stamp -- on the PC end I used a MAX232. The only drawback
Which "cheapy" did you use? What are you using for antennas? Wha is your
range and reliability?
Jay
signal -- did I miss something? I wound up using a transistor between the
receiver and the MAX232.
Original Message
> Whoops, typing to fast. Where I say:
>
> > Remember, you can get rid of the internal "max232". So if your
transciever
>
> I meant, of course, ... you can't get rid of...
whip antennas also. The maximum baud rate looks like 1200 -- I have not done
a range test yet, although it works in the office at about 25-30 feet.
We found another source for some 900 MHz transceivers, so we may try those
at a later date.
Original Message
> >I've used the cheapy AM 433 MHz transmitter and receiver to send data
> >to a PC from a Stamp -- on the PC end I used a MAX232. The only drawback
>
> Which "cheapy" did you use? What are you using for antennas? Wha is your
> range and reliability?
unit that worked with plenty of range and reliability -- no screwing around
with antennas-- was this one
http://www.parallaxinc.com/html_files/products/RF_Mods/27986-27991.asp
Jay
Original Message
From: Rodent [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=_3mRb5e4pJPoXLaQtAUd5hfzfQj33PN0DpuhBui727AjCqaK_67J1TeN5dTSLE1qop2X6AN_bI-j93aEpEs]daweasel@s...[/url
Sent: Wednesday, October 17, 2001 11:56 AM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
The ones Reynolds sells. TWS-434 and RWS-434 I think. I used their rubber
whip antennas also. The maximum baud rate looks like 1200 -- I have not done
a range test yet, although it works in the office at about 25-30 feet.
We found another source for some 900 MHz transceivers, so we may try those
at a later date.
Original Message
> >I've used the cheapy AM 433 MHz transmitter and receiver to send data
> >to a PC from a Stamp -- on the PC end I used a MAX232. The only drawback
>
> Which "cheapy" did you use? What are you using for antennas? Wha is your
> range and reliability?
To UNSUBSCRIBE, just send mail to:
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done, including one transmitter and receiver, a wall-wart, the MAX232, the
antennas and a nice plastic box, I spent $50. Now I can monitor my sensors,
etc... while the robot is in motion.
One of my cohorts in crime found some 900 MHz transceivers for $50 each, so
I may move on to those next. The PC box is built, and swapping RF modules is
easy.
Original Message
> I have tried several "cheapos" including the ones you mention. The only
RF
> unit that worked with plenty of range and reliability -- no screwing
around
> with antennas-- was this one
> http://www.parallaxinc.com/html_files/products/RF_Mods/27986-27991.asp
counterpart is with their antenna really easily. I used it to build a small
hovercraft that coule be controlled by my pc. I didn't use a max232 or any Smile
like that
Original Message
From: Rodent <daweasel@s...>
Date: Wed, 17 Oct 2001 23:24:58 -0500
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
> The main thing I wanted was a cheap, wireless debugging tool. All said and
> done, including one transmitter and receiver, a wall-wart, the MAX232, the
> antennas and a nice plastic box, I spent $50. Now I can monitor my sensors,
> etc... while the robot is in motion.
>
>
> One of my cohorts in crime found some 900 MHz transceivers for $50 each, so
> I may move on to those next. The PC box is built, and swapping RF modules is
> easy.
>
>
Original Message
>
> > I have tried several "cheapos" including the ones you mention. The only
> RF
> > unit that worked with plenty of range and reliability -- no screwing
> around
> > with antennas-- was this one
> > http://www.parallaxinc.com/html_files/products/RF_Mods/27986-27991.asp
>
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
--
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counterpart is with their antenna really easily. I used it to build a small
hovercraft that coule be controlled by my pc. I didn't use a max232 or any Smile
like that
Original Message
From: Rodent <daweasel@s...>
Date: Wed, 17 Oct 2001 23:24:58 -0500
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Stamp to PC via Serial RF
> The main thing I wanted was a cheap, wireless debugging tool. All said and
> done, including one transmitter and receiver, a wall-wart, the MAX232, the
> antennas and a nice plastic box, I spent $50. Now I can monitor my sensors,
> etc... while the robot is in motion.
>
>
> One of my cohorts in crime found some 900 MHz transceivers for $50 each, so
> I may move on to those next. The PC box is built, and swapping RF modules is
> easy.
>
>
Original Message
>
> > I have tried several "cheapos" including the ones you mention. The only
> RF
> > unit that worked with plenty of range and reliability -- no screwing
> around
> > with antennas-- was this one
> > http://www.parallaxinc.com/html_files/products/RF_Mods/27986-27991.asp
>
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
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Talk More, Pay Less with Net2Phone Direct(R), up to 1500 minutes free!
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