receiving long instead of a byte

Owen · 2007-01-13 13:13

I think this likely a basic question, but one I have yet to figure out. I have applicatio that i wrote wich controls a stepper motor via serial comands. I'm sending the number of steps for the motor to turn from a visual basic brogram I have writen but I only know how to send an array of bytes or a string through the serial port which is limiting the number of steps to 0-255. Is there a way to send a larger number? I need the propeller to see a number as large as 180,000. is there a way to send 4 seperate bytes and have the propeller create a long from them?
here is the current code i'm writing Is attached if it helps.
thanks,
Owen

scotta · 2007-01-13 16:16

long pos
byte b0,b1,b2,b3

b0:=serin
b1:=serin
b2:=serin
b3:=serin

pos[noparse][[/noparse]0]:=b0
pos:=b1
pos:=b2
pos:=b3

scotta · 2007-01-13 16:17

long pos
byte b0,b1,b2,b3

b0:=serin
b1:=serin
b2:=serin
b3:=serin

pos:=(b0<<24) and (b1<<16) and (b2<<8) and b3

scotta · 2007-01-13 16:18

long pos

pos:=(serin<<24) and (serin<<16) and (serin<<8) and serin

Owen · 2007-01-13 16:21

exactly what I needed !!!
thank you!

scotta · 2007-01-14 03:11

No problem dude

T Chap · 2007-01-14 06:24

Here are some snippets from the exact thing you are trying to do. I am using Real basic, and sending an ascii string with the position which can be any number, i.e. 180000. I first send a TAB delimted string from the application terminated with CR, here is a snippet of sending the X motor value, but in the program it sends each motor value one at a time just as shown, or separately as desired.

OutputString = "XID" + TAB + str(X) + CR     'Realbasic app sending first the motor ID, then the position.  str(X) is a value of the position, where is X is derived from sereral locations depending on who sent the motor move command(loaded from file, manual move etc)

The Propeller receives the two bytes, the ID then the position, and converts the ascii string to a 32 bit integer. After each set is rec'd, a case statement compares the ID to a list, if it is X then a variable X is updated, same for Y, Z, R. Another cog sends the motor to any newly arrived position.

CON
    _clkmode = xtal1 + pll16x   ' use crystal x 16
    _xinfreq = 5_000_000        ' 5 MHz cyrstal (sys clock = 80 MHz)

    TAB  =  $09
    CR    = $0D


VAR
    byte array[noparse][[/noparse]24]              ' buffer for numeric fields
    long X, Y, Z, R             ' these are actually 32 bit integers  
    long  temp1, temp2


OBJ               
 ser     : "fullduplexserial"
 term    : "tv_terminal"


PUB Start | i
 ser.start(0, 1, 0, 9600)      'rec tx mode baud
 term.start(12)     'enable TV terminal
  
  repeat
   if receiveStr(@array,24) <> TAB
     term.str(string("Missing TAB after temp1",CR))
     quit
   Temp1 := convertstr(@array)
   if receiveStr(@array,24) <> CR                                 
     term.str(string("Missing CR after temp2",CR))
     quit
   Temp2 := convertStr(@array)
   CaseTemp


PRI receiveStr(address,count) | c
  repeat count                   'start counting
   c := ser.rx                   'c = first rec'd byte
   if c == TAB or c == CR        'c == CR or TAB,                              
      byte[noparse][[/noparse]address] := 0 
      return c                   'now return delimiter for optional checking     
   byte[noparse][[/noparse]address++] := c          'update c                     
  return 0                       'default delimiter is zero

PRI getrx
   recbyte := ser.rx
PRI getarray  | i
  repeat i from 0 to 4
   if recbyte == $0D
     recbyte := 0 
  

PRI convertStr(address) | C
  repeat while c := byte[noparse][[/noparse]address++]
   result := result * 10 + (c - "0")

PRI  CaseTemp
   case temp1
         4270 : x := temp2    '4270 is decimal equiv to ascii string "XID"   , if it is X, then the vairable X is written to the value rec'd
                repeat until not lockset(SemId)
                RetEcheck(string("XID"), X)    'return the value back to the app to verify prior to motor run
                lockclr(SemId)
   case temp1
         4370 : y := temp2
                repeat until not lockset(SemId) 
                RetEcheck(string("YID"), Y)
                lockclr(SemId) 
   case temp1
         4470 : z := temp2
                repeat until not lockset(SemId) 
                RetEcheck(string("ZID"), Z)
                lockclr(SemId)
   case temp1
         3670 : r := temp2
                repeat until not lockset(SemId) 
                RetEcheck(string("RID"), R)
                lockclr(SemId)

Post Edited (originator) : 1/14/2007 8:54:01 AM GMT

receiving long instead of a byte

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