interfacing BS2 to C++ app

Archiver

I have been working on interfacing a C++ application to a BS2. I am able to
successfully send a single byte both to and from the stamp using SERIN and
SEROUT, but am having problems when sending multiple bytes as a string.
Basically, the stamp is sending out the data, but my C++ app is having
trouble parsing it. I am basically getting the value of the last byte sent
for both indices of my array. I'm sure it has to do with the way I am
reading in the data off the serial port, but am a newbie to this so bear
with me. I am using UserPort (a kernel mode driver) to access the I/O ports
in Win2k. Is there an easy way to "sync" the communication so I can store
each incoming byte as a seperate index in an array in my C++ app? Thanks in
advance,
Keith

'segment from Stamp code
stampOut var byte(3)
. . .
stampOut(0) = "5" 'junk test data
stampOut(1) = "6"
. . .
debug "stampOut(0) = ",stampOut(0), cr
debug "stampOut(1) = ",stampOut(1), cr
Serout 16,16468, [noparse][[/noparse]STR stampOut\2]

//code segment from C++ app
C_stampOut[noparse][[/noparse]0] = inportb(0x3F8);
printf("\nC_stampOut[noparse][[/noparse]0] = 0x%02X \n",C_stampOut[noparse][[/noparse]0]);
C_stampOut[noparse][[/noparse]1] = inportb(0x3F8);
printf("\nC_stampOut[noparse][[/noparse]1] = 0x%02X \n",C_stampOut[noparse][[/noparse]1]);

Archiver

You might enjoy http://www.al-williams.com/stampcom.zip -- this is an
example that uses VB or VC++ to read from a Stamp.

Al Williams
AWC
* Floating point A/D
http://www.al-williams.com/awce/pak9.htm


>

---

Original Message

---

> From: Keith Miller [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ANaAHEJbEsiiJb82Eqb48kM1jdMSsrs6IgVeDlYphwePpa0QXSxLN-z-gVHnn3nb51aIHykBxprh]keith@a...[/url
> Sent: Thursday, June 26, 2003 4:42 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] interfacing BS2 to C++ app
>
>
> I have been working on interfacing a C++ application to a
> BS2. I am able to successfully send a single byte both to
> and from the stamp using SERIN and SEROUT, but am having
> problems when sending multiple bytes as a string. Basically,
> the stamp is sending out the data, but my C++ app is having
> trouble parsing it. I am basically getting the value of the
> last byte sent for both indices of my array. I'm sure it has
> to do with the way I am reading in the data off the serial
> port, but am a newbie to this so bear with me. I am using
> UserPort (a kernel mode driver) to access the I/O ports in
> Win2k. Is there an easy way to "sync" the communication so I
> can store each incoming byte as a seperate index in an array
> in my C++ app? Thanks in advance, Keith
>
> 'segment from Stamp code
> stampOut var byte(3)
> . . .
> stampOut(0) = "5" 'junk test data
> stampOut(1) = "6"
> . . .
> debug "stampOut(0) = ",stampOut(0), cr
> debug "stampOut(1) = ",stampOut(1), cr
> Serout 16,16468, [noparse][[/noparse]STR stampOut\2]
>
> //code segment from C++ app
> C_stampOut[noparse][[/noparse]0] = inportb(0x3F8);
> printf("\nC_stampOut[noparse][[/noparse]0] = 0x%02X \n",C_stampOut[noparse][[/noparse]0]);
> C_stampOut[noparse][[/noparse]1] = inportb(0x3F8); printf("\nC_stampOut[noparse][[/noparse]1] =
> 0x%02X \n",C_stampOut[noparse][[/noparse]1]);
>
>
>
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Archiver

Hi

Your problem rises from the fact that the stamp's serial port is
echoing whatever character it receives. This is an inherent feature
of the stamp's serial line driver circuitry. You have to overcome
this by your software. Have your program prepared to receive (and
ignore) all characters it previously sent to the stamp before
receiving the rest of the reply. Furthermore, watch out to have
turned off local echo on the PC side (this would lead to infinite
bouncing of the characters).

PC

---

"xxx"

---

> stamp, replies with "yyy"
PC <

---

"xxxyyy"

---

stamp

Hope this helps
Adrian

Archiver

If you are using 'inportb', you are bypassing
all the Win buffering stuff.

You can do this, but you'll need to read the
8251 docs for the status register, to know when
a byte is ready. Then you'll have to grab the
byte before the next byte comes in.

You can dynamically set the FIFO level of your
serial chips, which should make this easier, as
the chip can then buffer up more than one byte.

Microsoft knows this is difficult, so they have
an MSCOMM control, which does all of this for
you. Interfacing the MSCOMM control in VB is
very straightforward -- I'm sure its similar
in C++, but I havn't done this yet personally.

If you're curious, you can search the Posts for
MSCOMM, or ask about using MSCOMM in VC++.

--- In basicstamps@yahoogroups.com, "Keith Miller" <keith@a...> wrote:
> I have been working on interfacing a C++ application to a BS2. I
am able to
> successfully send a single byte both to and from the stamp using
SERIN and
> SEROUT, but am having problems when sending multiple bytes as a
string.
> Basically, the stamp is sending out the data, but my C++ app is
having
> trouble parsing it. I am basically getting the value of the last
byte sent
> for both indices of my array. I'm sure it has to do with the way I
am
> reading in the data off the serial port, but am a newbie to this so
bear
> with me. I am using UserPort (a kernel mode driver) to access the
I/O ports
> in Win2k. Is there an easy way to "sync" the communication so I
can store
> each incoming byte as a seperate index in an array in my C++ app?
Thanks in
> advance,
> Keith
>
> 'segment from Stamp code
> stampOut var byte(3)
> . . .
> stampOut(0) = "5" 'junk test data
> stampOut(1) = "6"
> . . .
> debug "stampOut(0) = ",stampOut(0), cr
> debug "stampOut(1) = ",stampOut(1), cr
> Serout 16,16468, [noparse][[/noparse]STR stampOut\2]
>
> //code segment from C++ app
> C_stampOut[noparse][[/noparse]0] = inportb(0x3F8);
> printf("\nC_stampOut[noparse][[/noparse]0] = 0x%02X \n",C_stampOut[noparse][[/noparse]0]);
> C_stampOut[noparse][[/noparse]1] = inportb(0x3F8);
> printf("\nC_stampOut[noparse][[/noparse]1] = 0x%02X \n",C_stampOut[noparse][[/noparse]1]);