FullDuplexSerialPlus methods

ke4pjw

Is there a method in FullDuplexSerialPlus for receiving a single byte at a time? I need to capture binary serial data that may not have a CR in the packet. Is FullDuplexSerialPlus the best object to do this? Should I create my own method to do this?

Thanks in advance,
Terry

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-- Terry

Post Edited (ke4pjw) : 3/6/2010 9:54:30 PM GMT

Peter Jakacki

Isn't it the method "rx' which reads a byte from the buffer or waits for one otherwise? But I'm not quite sure what the question is then because this is how these objects are used normally so I must be missing something.

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*Peter*

Mike Green

How about just using FullDuplexSerial?

kwinn

There is rx which will wait for a byte, rxcheck which checks for a byte and returns the byte or returns -1 if there was no byte, and rxtime which waits for a specified time to receive a byte and returns the byte or -1 if it was not received in the specified time.

If the packet is sent sequentially with little or no delay between bytes and does not always have a specific last byte such as <cr> I would use rxtime with a suitable delay time.

Dr_Acula

Yes, I came across this problem with xmodem file transfers. One simple answer is to use rxcheck as kwinn suggests

PUB rxcheck : rxbyte

'' Check if byte received (never waits)
'' returns -1 if no byte received, $00..$FF if byte

  rxbyte--
  if rx_tail <> rx_head
    rxbyte := rx_buffer[noparse][[/noparse]rx_tail]
    rx_tail := (rx_tail + 1) & bufmsk

And like it says, if there is no byte available you get -1, and if there is then rxbyte contains the byte.

(as an aside, I needed another routine which would check if any bytes are available but not return the byte at that time. That is quite a simple routine, just a matter of seeing if rx_tail is equal to rx_head)

There are buffers in the serial code so data can be coming in and you can be reading it out asynchronously.

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www.smarthome.viviti.com/propeller

Peter Jakacki

Just as a side note I never use the rx or rxtime method but prefer the rxcheck method for various reasons, one is that I can do other things while waiting for input.

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*Peter*