Full duplex buffer question

Zap-o

Has anyone ever modified the full duplex object to hold the received data in a buffer? Then when I want, I can go into that buffer and read all of it.

Mike Green

The full duplex serial object already holds the received data in a buffer. The existing routines work one byte at a time because that's the simplest and most common case. You could add routines to the object that would use the existing buffer pointers and buffers and work with more than one character at a time.

What do you want to do with the buffer?

Cluso99

I did a mod to increase the buffer sizes up to 512 bytes as a parameter. See attached.

I also have a verson that holds the buffer (160 bytes each) in cog.

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Zap-o

@ mike
Well I am having problems running the FullDuplexSerial object and I end up missing some strings of data sent to it from a computer program. For example I have 2 cogs running, one the FullDuplexSerial and the "main cog" running all kinds of tasks. The "main cog" also packs the bytes into an array where the data can be compared as a command to execute by other cogs. When the computer program sends a series of strings (19200 baud) I end up missing the last 2 to 3. These strings contain roughly 9 - 20 bytes each.

So I wanted to create a buffer that could hold an array of bytes that my main cog could look at when its ready. This way I wont loose any commands. I hope this makes since...

@Cluso99
How do I get the buffer bytes?


Wish I knew machine code I could fix this issue...

Mike Green

The buffer size in the "standard" FullDuplexSerial object is only 16 bytes.· It's really easy to increase it to any power of 2 up to 512 bytes and not too hard to make it even larger.· There are several versions of FullDuplexSerial in the Object Exchange that have had the buffer size increased.· You could use Cluso99's version as well.·

With some strings up to 20 bytes long, you could lose the tail end of the string if your program isn't fast enough in emptying the receive buffer when it's only 16 bytes long.
·

Cluso99

Zap-o: Just use my version of FDX (posted above). Seems like you have a buffer overrun.
Just edit it and change the CON sizes of the buffers to what you want 16/32/64/128/256/512 and the following line for the use with the AND $xx instruction. You do not need anything else to use it in place of the real FullDuplexSerial. (My version takes the fixed coded buffer length and places it as a constant). There are a couple of minor additions which won't do any harm.

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Zap-o

Yea so I increased the buffer size but say I want to read the buffer after some time has passed. How do I go about this? Nothing comes to mind that is obvious, or as usual, I am looking in to this way to deeply.

So should I run a loop that reads the buffer? How do I run the loop?

This is kind of what I am thinking.

obj
coms :"FullDuplexSerial_rr004"

Main
IF coms.rxcheck > $00
'Repeat until buffer == 0 not sure how to go about this?
'pack my byte array here

Cluso99

IIRC there is a demo of FDX in the OBEX which shows how to do this.

repeat while coms.rxcheck == 0

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Links to other interesting threads:

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· Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)·
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Peter Jakacki

It's not at all hard to read in serial characters into a buffer but you can also work with the characters already in the buffer if you modify FullDuplexSerial just a tiny bit.

First off, increase the size of the receive buffers

  byte  rx_buffer[noparse][[/noparse]256]           'transmit and receive buffers

Now add/modify a flush method which will reset the buffer so it's ready to receive.

PUB rxflush
'' Flush receive buffer
  repeat while rxcheck => 0
  rx_head := rx_tail := 0

Then you need to be able to find the buffer as a string.

pub rxbuf   ' returns with address of rx_buffer as string
  rx_buffer[noparse][[/noparse]rx_head] := 0    ' null terminate characters as string
  result := @rx_buffer

And don't forget that you may simply need to know what the last character received was without upsetting the buffer. This way you can look for a terminator.

pub rxlast
  result := rx_bufffer[noparse][[/noparse]rx_head-1]                 '  edit - change to head not tail

All this assumes that you don't overflow the buffer with your input (shouldn't) and that you run rx_flush to prepare the buffer.

In your main method you can do this

pub demo
  coms.rxflush
  repeat until coms.rxlast == $0d   ' wait for a line terminated by a CR
  coms.str(coms.rxbuf)      ' demo print out the line once it's received

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*Peter*

Post Edited (Peter Jakacki) : 2/20/2010 6:21:53 AM GMT

Cluso99

Peter: Those calls are already available in FDX. You just call them. The buffer size is a little more intricate which is why I suggested my version which removes the constants embedded within the FDX code and places them in the CON section where the size can be altered simply.

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Links to other interesting threads:

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· Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
· Prop Tools under Development or Completed (Index)
· Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)·
· Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
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Peter Jakacki

Ray,

I didn't see these methods in FDX as you said. The flush is there but it does not reset the read indices though. I do have my own extensive and comprehensive serial coms routines (unicom) which I am getting around to releasing into the obex but the object of the exercise was to show how to access the buffers directly. I have just checked the latest version of FDX and it didn't do this.

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*Peter*

Zap-o

Cluso99 said...
IIRC there is a demo of FDX in the OBEX which shows how to do this.

repeat while coms.rxcheck == 0

What is the IIRC?

Cluso99

If I Recall Correctly

BTW (By the way) I have posted my modified FullDuplexSerial on OBEX

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Links to other interesting threads:

· Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
· Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
· Prop Tools under Development or Completed (Index)
· Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)·
· Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
My cruising website is: ·www.bluemagic.biz·· MultiBlade Props: www.cluso.bluemagic.biz

TonyWaite

IIRC ... 'If I Remember Correctly';

T o n y