Tying serial ports together

hinv

Hi

I am trying to tie in a 3.3v serial port to the console so that everything that comes in the serial port goes up to the serial console(usb on propdongle) and visa versa.

Right now, I have a main loop that looks like:

repeat
  wireser.tx(usbser.rx)
  usbser.tx(wireser.rx)

The problem is I don't get a character one way without getting a character the other way because usbser.rx waits for a character.
I am sure somebody has done this before. Any hints?

Thanks,
Doug

Oldbitcollector (Jeff)

hinv said...
Hi

The problem is I don't get a character one way without getting a character the other way because usbser.rx waits for a character.
I am sure somebody has done this before. Any hints?

Thanks,
Doug

repeat
  wireser.tx(usbser.rxtime(20))
  usbser.tx(wireser.rxtime(20))

It's been a while since I've done communication code, but I *think* the above
should work without stopping and waiting..

OBC

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Ken Peterson

@hinv: try using a non-blocking call

var
byte char

repeat
  if (char := wireser.rxcheck) <> -1
    usbser.tx(char)
  if (char := usbser.rxcheck) <> -1
    wireser.tx(char)  

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hinv

Thanks,
I used

var
word n,o

repeat
  if ((n := usbser.rxcheck) > 0)
    wireser.tx(n)
  repeat while (o := wireser.rxcheck) > 0
    usbser.tx(o)

If I didn't use the later repeat, it dropped a lot more characters coming back from the router I am connecting to. It still drops way too much, but it is a little better with the repeat in there. If I knew how, I would set the serial port on the router (wgt634u running openwgt) to something a little slower, and hopefully fix the dropped character problem. I will also try upping the buffer size to 256 characters instead of 64 to see if that helps. BTW, thanks to whoever modified BB_FullDuplexSerial as I get to make this change.
It could be my terminal also as I am using propTerminal in "Normal-Terminal Mode", and hyperterm is not available. Next I will try on a real os ie Linux where I have tools to work with(except on the prop side)

Jimmy W.

I recommend you use (n := usbser.rxcheck() ) > -1
because 0 is a valid value that can be sent

Jimmy

hinv

Thanks for the tip

hippy

Isn't the obvious solution to put each in their own separate Cog / thread so each runs in parallel rather then sequentially ? This is where the Propeller beats most other micros hands down.

PUB Main
  CogNew( wire2usb, @wire2usbStack )
  CogNew( usb2wire, @usb2wireStack )
  repeat
    twiddleThumbs

PRI wire2Usb
  repeat
    wireser.tx(usbser.rx)

PRI usb2wire
  repeat
    usbser.tx(wireser.rx)

Ken Peterson

Or you can venture into the fun and entertaining world of PASM programming!

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hinv

@hippy: Thanks for the suggestion, but I thought that any time assembly was used, it was started in it's own cog. I thought each instance of BB_FullDuplexSerial ran in it's own cog and the main cog ran the spin tying them together.
With your example would I be using 5 cogs?

Thanks,
Doug

hippy

In that case it could be. There's always a compromise, maximum speed and more cogs used or less cogs and slower operation.

Timmoore

If you are running multiple serial ports and want to save cogs, look for the multiple serial port thread. There is a serial port driver that runs 4 serial ports on 1 cog.