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Discussion Groups | | oSerialH on ooPIC-R, TTL-Level or true RS232?
oSerialH on ooPIC-R, TTL-Level or true RS232? - "design.wonk" - Apr 10 11:51:55 2008
I was looking at the oSerialH object (after trouble with the oSerialL)
and it appears that the oSerialH on the ooPIC-R is "hard wired" to
line 22 for output and line 23 for input. These are connected to pins
2 and 3 respectively of the db9 connector. If I am reading the
schematics correctly, are pins 2 and 3 of the db9 providing +5V
TTL-Level signals and not true +12v RS232c signals (in that case I
should be able to connect them to another device with similar +5V
TTL-Level input and output pins).
thanks
-GeorgeOrr
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
and it appears that the oSerialH on the ooPIC-R is "hard wired" to
line 22 for output and line 23 for input. These are connected to pins
2 and 3 respectively of the db9 connector. If I am reading the
schematics correctly, are pins 2 and 3 of the db9 providing +5V
TTL-Level signals and not true +12v RS232c signals (in that case I
should be able to connect them to another device with similar +5V
TTL-Level input and output pins).
thanks
-GeorgeOrr
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - dan michaels - Apr 10 12:20:39 2008
--- In o...@yahoogroups.com, "design.wonk" wrote:
>
> I was looking at the oSerialH object (after trouble with the
oSerialL)
> and it appears that the oSerialH on the ooPIC-R is "hard wired" to
> line 22 for output and line 23 for input. These are connected to
pins
> 2 and 3 respectively of the db9 connector. If I am reading the
> schematics correctly, are pins 2 and 3 of the db9 providing +5V
> TTL-Level signals and not true +12v RS232c signals (in that case I
> should be able to connect them to another device with similar +5V
> TTL-Level input and output pins).
>
> thanks
>
> -GeorgeOrr
>
Yes. The oSerialH and oSerialPort [buffered form] objects use the
main UART on the oopic [PIC] chip for RS232 comms, via the DB09
connector. However, for some reason, the oopic-r board uses a 0-5v
logic level inverter, rather than a MAX232 style inverter chip with
+/-12v levels. According to DennisLC, this interface works
with "most" PCs [but not all; eg, it works with my old notebook PC,
but not my desktop PC].
You should be able to connect the oopic-r board to other logic-level
serial ports, but you will still need an inverter on the remote end.
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
>
> I was looking at the oSerialH object (after trouble with the
oSerialL)
> and it appears that the oSerialH on the ooPIC-R is "hard wired" to
> line 22 for output and line 23 for input. These are connected to
pins
> 2 and 3 respectively of the db9 connector. If I am reading the
> schematics correctly, are pins 2 and 3 of the db9 providing +5V
> TTL-Level signals and not true +12v RS232c signals (in that case I
> should be able to connect them to another device with similar +5V
> TTL-Level input and output pins).
>
> thanks
>
> -GeorgeOrr
>
Yes. The oSerialH and oSerialPort [buffered form] objects use the
main UART on the oopic [PIC] chip for RS232 comms, via the DB09
connector. However, for some reason, the oopic-r board uses a 0-5v
logic level inverter, rather than a MAX232 style inverter chip with
+/-12v levels. According to DennisLC, this interface works
with "most" PCs [but not all; eg, it works with my old notebook PC,
but not my desktop PC].
You should be able to connect the oopic-r board to other logic-level
serial ports, but you will still need an inverter on the remote end.
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - "design.wonk" - Apr 10 12:34:11 2008
--- In o...@yahoogroups.com, "dan michaels" wrote:
>
> --- In o...@yahoogroups.com, "design.wonk" wrote:
> >
> > I was looking at the oSerialH object (after trouble with the
> oSerialL)
> > and it appears that the oSerialH on the ooPIC-R is "hard wired" to
> > line 22 for output and line 23 for input. These are connected to
> pins
> > 2 and 3 respectively of the db9 connector. If I am reading the
> > schematics correctly, are pins 2 and 3 of the db9 providing +5V
> > TTL-Level signals and not true +12v RS232c signals (in that case I
> > should be able to connect them to another device with similar +5V
> > TTL-Level input and output pins).
> >
> > thanks
> >
> > -GeorgeOrr
> >
> Yes. The oSerialH and oSerialPort [buffered form] objects use the
> main UART on the oopic [PIC] chip for RS232 comms, via the DB09
> connector. However, for some reason, the oopic-r board uses a 0-5v
> logic level inverter, rather than a MAX232 style inverter chip with
> +/-12v levels. According to DennisLC, this interface works
> with "most" PCs [but not all; eg, it works with my old notebook PC,
> but not my desktop PC].
>
> You should be able to connect the oopic-r board to other logic-level
> serial ports, but you will still need an inverter on the remote end.
>
If the remote end is also 0-5V, then I would not need the inverter -
is that correct?
------------------------------------
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>
> --- In o...@yahoogroups.com, "design.wonk"
> >
> > I was looking at the oSerialH object (after trouble with the
> oSerialL)
> > and it appears that the oSerialH on the ooPIC-R is "hard wired" to
> > line 22 for output and line 23 for input. These are connected to
> pins
> > 2 and 3 respectively of the db9 connector. If I am reading the
> > schematics correctly, are pins 2 and 3 of the db9 providing +5V
> > TTL-Level signals and not true +12v RS232c signals (in that case I
> > should be able to connect them to another device with similar +5V
> > TTL-Level input and output pins).
> >
> > thanks
> >
> > -GeorgeOrr
> >
> Yes. The oSerialH and oSerialPort [buffered form] objects use the
> main UART on the oopic [PIC] chip for RS232 comms, via the DB09
> connector. However, for some reason, the oopic-r board uses a 0-5v
> logic level inverter, rather than a MAX232 style inverter chip with
> +/-12v levels. According to DennisLC, this interface works
> with "most" PCs [but not all; eg, it works with my old notebook PC,
> but not my desktop PC].
>
> You should be able to connect the oopic-r board to other logic-level
> serial ports, but you will still need an inverter on the remote end.
>
If the remote end is also 0-5V, then I would not need the inverter -
is that correct?
------------------------------------
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Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - rtstofer - Apr 10 13:57:59 2008
> If the remote end is also 0-5V, then I would not need the inverter -
> is that correct?
>
Right! The DB-9 output is inverted and the remote end would need to
re-invert the signals.
HOWEVER, a regular level shifter MAY accept the 0-5V signals (it
usually will) and provide the inversion. Besides, it mistake-proofs
the system. So just use the level shifter at the remote end just as
though you were connecting to a PC.
REMEMBER, you will need a NULL MODEM cable. Pin 2 on the first end
connects to pin 3 on the second. Same for pin 3 on one first end
connecting to pin 2 on the second. Pin 5 common on both ends. Both
connectors to be DB-9 MALE.
Richard
------------------------------------
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Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - "design.wonk" - Apr 10 14:12:10 2008
Just curious... How is the oooPIC-R able to communicate with my PC
using a serial cable with no inverter?
--- In o...@yahoogroups.com, "rtstofer" wrote:
> > If the remote end is also 0-5V, then I would not need the inverter -
> > is that correct?
> > Right! The DB-9 output is inverted and the remote end would need to
> re-invert the signals.
>
> HOWEVER, a regular level shifter MAY accept the 0-5V signals (it
> usually will) and provide the inversion. Besides, it mistake-proofs
> the system. So just use the level shifter at the remote end just as
> though you were connecting to a PC.
>
> REMEMBER, you will need a NULL MODEM cable. Pin 2 on the first end
> connects to pin 3 on the second. Same for pin 3 on one first end
> connecting to pin 2 on the second. Pin 5 common on both ends. Both
> connectors to be DB-9 MALE.
>
> Richard
>
------------------------------------
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using a serial cable with no inverter?
--- In o...@yahoogroups.com, "rtstofer"
> > If the remote end is also 0-5V, then I would not need the inverter -
> > is that correct?
> > Right! The DB-9 output is inverted and the remote end would need to
> re-invert the signals.
>
> HOWEVER, a regular level shifter MAY accept the 0-5V signals (it
> usually will) and provide the inversion. Besides, it mistake-proofs
> the system. So just use the level shifter at the remote end just as
> though you were connecting to a PC.
>
> REMEMBER, you will need a NULL MODEM cable. Pin 2 on the first end
> connects to pin 3 on the second. Same for pin 3 on one first end
> connecting to pin 2 on the second. Pin 5 common on both ends. Both
> connectors to be DB-9 MALE.
>
> Richard
>
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - rtstofer - Apr 10 15:11:34 2008
--- In o...@yahoogroups.com, "design.wonk" wrote:
>
> Just curious... How is the oooPIC-R able to communicate with my PC
> using a serial cable with no inverter?
The logic levels (0 and 1) are corrected for RS232 definitions of mark
and space by inverting the TTL signals from the uC. The PC has level
changers as well inverting the signal from the SuperIO chip (the
likely chip).
The unfortunate thing is that the OOPic-R (and -C) inverted signals
are NOT really RS232 voltage levels. So, while the OOPic-R can talk
to a PC, there are a number of things it can't talk to. Some
USB->Serial cables, for example. A real level shifter will come a lot
closer to RS232 voltage levels - usually on the lower side of the
voltage range but definitely both above and below ground.
Nevertheless, it all kind of works out.
Richard
------------------------------------
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>
> Just curious... How is the oooPIC-R able to communicate with my PC
> using a serial cable with no inverter?
The logic levels (0 and 1) are corrected for RS232 definitions of mark
and space by inverting the TTL signals from the uC. The PC has level
changers as well inverting the signal from the SuperIO chip (the
likely chip).
The unfortunate thing is that the OOPic-R (and -C) inverted signals
are NOT really RS232 voltage levels. So, while the OOPic-R can talk
to a PC, there are a number of things it can't talk to. Some
USB->Serial cables, for example. A real level shifter will come a lot
closer to RS232 voltage levels - usually on the lower side of the
voltage range but definitely both above and below ground.
Nevertheless, it all kind of works out.
Richard
------------------------------------
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Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - dan michaels - Apr 10 16:15:21 2008
--- In o...@yahoogroups.com, "design.wonk" wrote:
>
> >
> > You should be able to connect the oopic-r board to other logic-
level serial ports, but you will still need an inverter on the remote
end.
> > If the remote end is also 0-5V, then I would not need the inverter -
> is that correct?
>
No, the remote end would still need a logic-level inverter, unless you
were using a software UART and were able to deal with inverted input.
Inversion is orthogonal to voltage-levels used [ie, they are
completely independent issues].
------------------------------------
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>
> >
> > You should be able to connect the oopic-r board to other logic-
level serial ports, but you will still need an inverter on the remote
end.
> > If the remote end is also 0-5V, then I would not need the inverter -
> is that correct?
>
No, the remote end would still need a logic-level inverter, unless you
were using a software UART and were able to deal with inverted input.
Inversion is orthogonal to voltage-levels used [ie, they are
completely independent issues].
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - dan michaels - Apr 10 16:16:29 2008
--- In o...@yahoogroups.com, "design.wonk" wrote:
>
The inverter is inside the PC.
> Just curious... How is the oooPIC-R able to communicate with my PC
> using a serial cable with no inverter?
>
> --- In o...@yahoogroups.com, "rtstofer" wrote:
> >
> >
> > > If the remote end is also 0-5V, then I would not need the
inverter -
> > > is that correct?
> > >
> >
> > Right! The DB-9 output is inverted and the remote end would need
to
> > re-invert the signals.
> >
> > HOWEVER, a regular level shifter MAY accept the 0-5V signals (it
> > usually will) and provide the inversion. Besides, it mistake-
proofs
> > the system. So just use the level shifter at the remote end just
as
> > though you were connecting to a PC.
> >
> > REMEMBER, you will need a NULL MODEM cable. Pin 2 on the first
end
> > connects to pin 3 on the second. Same for pin 3 on one first end
> > connecting to pin 2 on the second. Pin 5 common on both ends.
Both
> > connectors to be DB-9 MALE.
> >
> > Richard
>
------------------------------------
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>
The inverter is inside the PC.
> Just curious... How is the oooPIC-R able to communicate with my PC
> using a serial cable with no inverter?
>
> --- In o...@yahoogroups.com, "rtstofer"
> >
> >
> > > If the remote end is also 0-5V, then I would not need the
inverter -
> > > is that correct?
> > >
> >
> > Right! The DB-9 output is inverted and the remote end would need
to
> > re-invert the signals.
> >
> > HOWEVER, a regular level shifter MAY accept the 0-5V signals (it
> > usually will) and provide the inversion. Besides, it mistake-
proofs
> > the system. So just use the level shifter at the remote end just
as
> > though you were connecting to a PC.
> >
> > REMEMBER, you will need a NULL MODEM cable. Pin 2 on the first
end
> > connects to pin 3 on the second. Same for pin 3 on one first end
> > connecting to pin 2 on the second. Pin 5 common on both ends.
Both
> > connectors to be DB-9 MALE.
> >
> > Richard
>
------------------------------------
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Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - "design.wonk" - Apr 12 15:37:56 2008
OK, I just got an inverter. My understanding is that the RS232 on the
ooPIC is connected to the inverter in the following manner:
ooPIC-R Pin Inverter Pin
2 3
3 2
5 5
Is that the correct pin configuration? What about the other pins?
thanks
--- In o...@yahoogroups.com, "dan michaels" wrote:
>
> --- In o...@yahoogroups.com, "design.wonk" wrote:
> > > >
> > > You should be able to connect the oopic-r board to other logic-
> level serial ports, but you will still need an inverter on the remote
> end.
> > >
> >
> >
> >
> > If the remote end is also 0-5V, then I would not need the inverter -
> > is that correct?
> >
> No, the remote end would still need a logic-level inverter, unless you
> were using a software UART and were able to deal with inverted input.
> Inversion is orthogonal to voltage-levels used [ie, they are
> completely independent issues].
>
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
ooPIC is connected to the inverter in the following manner:
ooPIC-R Pin Inverter Pin
2 3
3 2
5 5
Is that the correct pin configuration? What about the other pins?
thanks
--- In o...@yahoogroups.com, "dan michaels"
>
> --- In o...@yahoogroups.com, "design.wonk"
> > > >
> > > You should be able to connect the oopic-r board to other logic-
> level serial ports, but you will still need an inverter on the remote
> end.
> > >
> >
> >
> >
> > If the remote end is also 0-5V, then I would not need the inverter -
> > is that correct?
> >
> No, the remote end would still need a logic-level inverter, unless you
> were using a software UART and were able to deal with inverted input.
> Inversion is orthogonal to voltage-levels used [ie, they are
> completely independent issues].
>
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - rtstofer - Apr 12 15:51:07 2008
--- In o...@yahoogroups.com, "design.wonk" wrote:
>
> OK, I just got an inverter. My understanding is that the RS232 on the
> ooPIC is connected to the inverter in the following manner:
>
> ooPIC-R Pin Inverter Pin
>
> 2 3
> 3 2
> 5 5
> Is that the correct pin configuration? What about the other pins?
You got an RS232 level shifter?
Yes that is the configuration of the interconnecting cable. The other
pins are unused in this application.
Richard
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
>
> OK, I just got an inverter. My understanding is that the RS232 on the
> ooPIC is connected to the inverter in the following manner:
>
> ooPIC-R Pin Inverter Pin
>
> 2 3
> 3 2
> 5 5
> Is that the correct pin configuration? What about the other pins?
You got an RS232 level shifter?
Yes that is the configuration of the interconnecting cable. The other
pins are unused in this application.
Richard
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - "design.wonk" - Apr 12 16:19:07 2008
Sorry if my terminology is a little off. It is a Pololu 23201a
adapter. I think that is the part that I needed.
--- In o...@yahoogroups.com, "rtstofer" wrote:
>
> --- In o...@yahoogroups.com, "design.wonk" wrote:
> >
> > OK, I just got an inverter. My understanding is that the RS232 on the
> > ooPIC is connected to the inverter in the following manner:
> >
> > ooPIC-R Pin Inverter Pin
> >
> > 2 3
> > 3 2
> > 5 5
> >
> >
> > Is that the correct pin configuration? What about the other pins?
>
> You got an RS232 level shifter?
>
> Yes that is the configuration of the interconnecting cable. The other
> pins are unused in this application.
>
> Richard
>
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
adapter. I think that is the part that I needed.
--- In o...@yahoogroups.com, "rtstofer"
>
> --- In o...@yahoogroups.com, "design.wonk"
> >
> > OK, I just got an inverter. My understanding is that the RS232 on the
> > ooPIC is connected to the inverter in the following manner:
> >
> > ooPIC-R Pin Inverter Pin
> >
> > 2 3
> > 3 2
> > 5 5
> >
> >
> > Is that the correct pin configuration? What about the other pins?
>
> You got an RS232 level shifter?
>
> Yes that is the configuration of the interconnecting cable. The other
> pins are unused in this application.
>
> Richard
>
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - "design.wonk" - Apr 14 11:07:05 2008
Bingo! It works. My ooPIC-R is now controlling the mp3 player
through the RS232 port.
Thank you Richard and everyone else who helped. My project prototype
is now complete.
--- In o...@yahoogroups.com, "rtstofer" wrote:
>
> --- In o...@yahoogroups.com, "design.wonk" wrote:
> >
> > OK, I just got an inverter. My understanding is that the RS232 on the
> > ooPIC is connected to the inverter in the following manner:
> >
> > ooPIC-R Pin Inverter Pin
> >
> > 2 3
> > 3 2
> > 5 5
> >
> >
> > Is that the correct pin configuration? What about the other pins?
>
> You got an RS232 level shifter?
>
> Yes that is the configuration of the interconnecting cable. The other
> pins are unused in this application.
>
> Richard
>
------------------------------------
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through the RS232 port.
Thank you Richard and everyone else who helped. My project prototype
is now complete.
--- In o...@yahoogroups.com, "rtstofer"
>
> --- In o...@yahoogroups.com, "design.wonk"
> >
> > OK, I just got an inverter. My understanding is that the RS232 on the
> > ooPIC is connected to the inverter in the following manner:
> >
> > ooPIC-R Pin Inverter Pin
> >
> > 2 3
> > 3 2
> > 5 5
> >
> >
> > Is that the correct pin configuration? What about the other pins?
>
> You got an RS232 level shifter?
>
> Yes that is the configuration of the interconnecting cable. The other
> pins are unused in this application.
>
> Richard
>
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
Re: oSerialH on ooPIC-R, TTL-Level or true RS232? - rtstofer - Apr 14 11:33:40 2008
--- In o...@yahoogroups.com, "design.wonk" wrote:
>
> Bingo! It works. My ooPIC-R is now controlling the mp3 player
> through the RS232 port.
>
> Thank you Richard and everyone else who helped. My project prototype
> is now complete.
Outstanding! FWIW, I have several of those RS232 adapters. You may
wish to have a couple of extras laying around.
Richard
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )
>
> Bingo! It works. My ooPIC-R is now controlling the mp3 player
> through the RS232 port.
>
> Thank you Richard and everyone else who helped. My project prototype
> is now complete.
Outstanding! FWIW, I have several of those RS232 adapters. You may
wish to have a couple of extras laying around.
Richard
------------------------------------
(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )