Full Duplex Serial

172heavy · 2010-09-12 12:27

I am new to the prop so please excuse this basic question, I have been experimenting with the full duplex serial and I have figured out how to send data to a terminal program, my question is this, How is this object designed to recieve and store data? If I want to receive a string or dec or whatever what needs to be done? Where do I store it? I am assuming I need a variable but how do I point the received byte(s) to the variable?

Thanks in Advance

Josh

172heavy · 2010-09-12 13:36

........Is this one a stumper or what?

ElectricAye · 2010-09-12 13:43

172heavy wrote: »

........Is this one a stumper or what?

You might take a look at the pages starting around pp. 95-100, 103, etc, of the free downloadable PE Labs Fun book:
http://www.parallax.com/Portals/0/Downloads/docs/prod/prop/PELabsFunBook-v1.1.pdf

hope that helps,

StefanL38 · 2010-09-12 13:45

Hello and Welcome to the Prop-Forum !

variables in SPIN are bytes (8bit), words (16bit) or longs (32bit).

FullDuplexSerial (short FDX) works with bytes

So for receiving a single byte you have to declare a bytevariable

VAR
  byte MyReceivedByte

If you want to receive strings you have to declare an array of bytes

VAR
  byte MyByteArray[ 11 ]

ATTENTION! Your bytearray has to be one byte longer than your maximum
stringlength you want to receive. In the last byte a zero is stored to indicate the end of the string

So called zero-terminated strings.
If you want to access single bytes of this string the index starts at zero

  MyByteArray[ 0 ]

for receiving strings you should use FullDuplexSerialPlus
which provides a method "getstr"

PUB getstr(stringptr) | index
    '' Gets zero terminated string and stores it, starting at the stringptr memory address
    index~
    repeat until ((byte[stringptr][index++] := rx) == 13)
    byte[stringptr][--index]~

that alreday does the details of receiving the bytes
The parameter is a long that points to bytearray

@the forum:

I don't have example-code for receiving strings handy

can someone post a working example?

best regards

Stefan

172heavy · 2010-09-12 13:55

Thanks guys, this should be enough of a push, I hope the "stumper" comment didn't come off as rude I sometimes type before I think, I really appreciate your input!

Mike Green · 2010-09-12 14:31

In the Propeller Object Exchange, there's an object that does much of what you want. Basically, it sits between your program and FullDuplexSerial and provides some methods to input decimal, hexadecimal, and text strings and convert them to a useful format. Have a look at it.

172heavy · 2010-09-12 16:44

So I have been looking for the FullDuplexSerialPlus in the OBEX and I cannot find it, any pointers?

172heavy · 2010-09-12 16:57

172heavy wrote: »

So I have been looking for the FullDuplexSerialPlus in the OBEX and I cannot find it, any pointers?

Nevermind, I found it........

Cluso99 · 2010-09-12 21:13

Welcome to the forum. You will find this a fantastic forum with help from many people only questions away. And you will love the prop!!

172heavy · 2010-09-12 21:50

Is it possible to get the get.string command to wait in this object? or count characters?

For Example if I have a string if data coming in like this,

$GMRMC,1234.555,N,1234,5555,W Etc........ If I only want to save the first "1234" how can I do this if I want to count 7 characters and then capture 4

PUB rx : rxbyte

'' Receives byte (may wait for byte)
'' rxbyte returns $00..$FF

repeat while (rxbyte := rxcheck) < 0

I can do this using my BS2, but I wanted to try to move up to the PROP.........

wjsteele · 2010-09-13 04:16

Hi 172Heavy,

First off, I love the name... But I guess only pilots would get it. ;-)

Second, there is another object in the OBEX that does exactly what you are looking for. It's called GPS_IO. It uses FullDuplexSerial and adds specific parsing functions for handling NMEA strings.

I've modified it for several other string parsers, which is quite easy to do once you see how it works.

Bill

172heavy · 2010-09-13 20:28

wjsteele wrote: »

Hi 172Heavy,

First off, I love the name... But I guess only pilots would get it. ;-)

Second, there is another object in the OBEX that does exactly what you are looking for. It's called GPS_IO. It uses FullDuplexSerial and adds specific parsing functions for handling NMEA strings.

I've modified it for several other string parsers, which is quite easy to do once you see how it works.

Bill

Thank you, I appreciate the compliment and the advice. I like your picture by the way, what are you flying?

172heavy · 2010-09-13 21:09

Bill,

I have checked the OBEX and I cannot find the GPS_IO do you have a copy you could email to me or do you know where it is? It looks like there are several other Objects that will help though.

Thanks

ratronic · 2010-09-13 21:41

172heavy - I'm not sure if this is the one wjsteele was talking about but this one contains a gps parsing file called GPS_IO_mini.spin that I use.

172heavy · 2010-09-14 13:26

ratronic wrote: »

172heavy - I'm not sure if this is the one wjsteele was talking about but this one contains a gps parsing file called GPS_IO_mini.spin that I use.

Dave, that is exactly what I was looking for! You and Bill have been a great help!

Is that a tail number I spot on your sig line?

w8an · 2010-09-14 17:20

172heavy wrote: »

Is that a tail number I spot on your sig line?

I believe that is a ham (amateur radio) callsign. You'll find many hams hanging around in this forum.

Steve

ratronic · 2010-09-14 17:42

yes 172heavy that is my amateur radio call sign.

Full Duplex Serial

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