Canada
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Resolved Resolved by mtiberia!

Uart Receive Query. Buffer Flush Command?

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I am have a little issue with the below code.... I am attempting to read 3 different single byte return sensors on my new Create 2.... Now, it works perfectly if I read only one sensor in the repeatuntil loop. However if I do more than one read (like the code below).... the readings report back false... i.e. the bump sensor will indicate a bump when none occurred or the IR detect will indicate a bump instead of a indicating a close proximity of an object....

So am I daft and my code is wrong or does maybe the UART buffer need to be flushed after each read?

I am stumped....

Thanks guys


REPEATUNTIL(1=2)
  $x=0
  $y=0
  $z=0
  
  uartWrite(0,1,142,45) # Read Roomba IR sensors single byte
  sleep(10)
  
  IF (UARTAvailable(0,1)>0)
    $x=UARTRead(0,1,1)
    $x=GetByte($x)
  ENDIF 
    
    
  sleep(10)
  
  uartWrite(0,1,142,7) #Roomba Bump and wheel drop sensor single byte
  sleep(10)
  
  IF (UARTAvailable(0,1)>0)
    $y=UARTRead(0,1,1)
    $y=GetByte($y)
  ENDIF 
    
  sleep(10)
  
  uartWrite(0,1,142,58) # Stasis (Rommba moving forward) single byte
  sleep(10)
  IF (UARTAvailable(0,1)>0)
    $z=UARTRead(0,1,1)
    $z=GetByte($z)
  ENDIF 
    
  print($x+" IR light object detected")
  print($y+" bump detected")
  print($z+" Is moving forward")
  
  sleep(200)
ENDREPEATUNTIL

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Canada
#9  

Interesting try placing the initiate UART inside the loop. That should flush the buffer.

#10  

@mtiberia That didn't work either... the first read gives me the out of bounds of the array error.... This is the same problem I had way back when I first tried to do this with my old create 1... I was able to read single byte data but not anything with more than 1 byte.... This works on an Arduino and on my ancient Basic Atom Pro....

Either I am doing something wrong of you are correct the UART port doesn't work correctly on the EZB4

Canada
#11  

I just noticed an error in your code, I'm fighting the need for reading glasses, but try changing your code to the following.

if($rx=2) $RX_DATA = UARTRead(0, 1, $rx) $MSB=GetByteAt($RX_DATA,0)
$LSB=GetByteAt($RX_DATA,1)

Canada
#12  

That was my bad the above should work for you.

#13  

You're eyes are just fine... good catch dude....Can't believe I missed that as well....

Ok the code below seems to work, however if you don't have the uartinit() in the loop the buffer just continues to grow...


REPEATUNTIL(1=2)
 uartinit(0, 1, 115200) #used to flush the buffer
sleep(20)
   $RX_DATA=0
  uartWrite(0,1,142,22) # Volatge check
  sleep(10)
  $rx = UartAvailable(0, 1)
  
  print($rx+" bytes in the buffer")
  
  IF ($rx=2)
    $RX_DATA = UARTRead(0, 1, $rx)
    $MSB=GetByteAt($RX_DATA,0)
    $LSB=GetByteAt($RX_DATA,1)
    $voltage=$LSB+(256*$MSB)
    print($voltage)
  ENDIF 
  sleep(225)
  
ENDREPEATUNTIL
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