Transmit data between 2 propellers - please Help!

koze85 · 2010-07-02 05:43

Hello, I have managed to setup 2 propellers running with the same configuration and from the same power output (Same Vss). The one collects data from various sensors and the other one must log them to a datalogger. I 've managed to make this two tasks work but i cannot connect the two propellers together so i can transmit the information between the propellers. I tried the fast inter-propeller object with no luck. Can i use a serial object to transmit decimal numbers and strings between the propellers? what is the simplest way to transmit data between 2 propellers? As far as i can understand i need to dedicate two pins in each propeller for rx tx communication and connect the first propeller tx pin to the second propeller rx and vice versa with 10k resistors for safety. Please help me i am a bit of desperate here because of university project that i have… I am a bit of newbie with propeller
Thanks in advance

Ale · 2010-07-02 06:25

There are a number of ways, using FullDuplexSerial or a similar object and connecting tx->rx and rx->tx should work. series resistors are not needed and if you use them... 10 k is just too much. 100 or 150 ohm should suffice.

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koze85 · 2010-07-02 12:10

ok so i will not use resistors suppose i connected two propellers in 14 and 15 pins rx tx for the one is tx rx for the other one
then for the transmit propeller i use this code

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000
 
obj
PST        :"Parallax Serial Terminal"
Sub Transmit

repeat
PST.StartRxTx(14, 15, 0, 57600) 'Connect to the other propeller
pst.Str(String("just a string")) 'send a string
pst.Dec(123)                    'send a value

and on the receiver this code

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000
VAR
BYTE       dataBuffer[noparse][[/noparse]30]

obj |sl
  PST   :       "Parallax Serial Terminal"
  text  :       "tv_text"
  F     :       "FloatMath"
  FS    :       "FloatString"

Sub Receive
text.start(20)                  'start tv object in pins 20,21,22,23

PST.StartRxTx(15, 14, 0, 57600) 'Connect to the other propeller

repeat
 
  text.str(FS.FloatToString(F.FFloat(pst.StrIn(databuffer)))) 'receive and show string
 
  text.str(FS.FloatToString(F.FFloat(pst.StrIn(pst.DecIn))))  'receive and show value

Will this work or i am writing irrelevant things???
thank you

koze85 · 2010-07-02 12:57

Ok this code works fine, taken from Clock Loop post at http://forums.parallax.com/showthread.php?p=850318·for transmiting one byte but how can i transmit a decimal value or a string lets say "hello world" and 123.456
transmit propeller

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000
VAR
BYTE       Fx[noparse][[/noparse]60]
obj
comm        :"FullDuplexSerialPlus"

Pub Transmit |go, bpmstep

comm.Start(14, 15, 0, 115200) 'Connect to the other propeller
bpmstep:=123
 
Repeat
  go := 0
  Comm.tx(213)                        'transmit sync number
    waitcnt(500 + cnt)              'wait for other prop to catch up
    Comm.tx(BpmStep)                 ' transmit BpmStep position
  waitcnt(500 + cnt)
  If Comm.rxtime(1) == 214
    Repeat go from 0 to 1000              ' get range of memory
      Fx[noparse][[/noparse]go] := Comm.rx

and receiver propeller

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000
VAR
BYTE       Fx[noparse][[/noparse]60]
obj
  comm        :"FullDuplexSerialPlus"
  text  :       "tv_text"
  F     :       "FloatMath"
  FS    :       "FloatString"
 
 
Pub Receive |go, bpmstep
text.start(20)                  'start tv object in pins 20,21,22,23

comm.Start(15, 14, 0, 115200) 'Connect to the other propeller
repeat
 go := 0
  If Comm.rxtime(1) == 213     'this looks for start number of 213
    BpmStep := Comm.rx        'then receives data and puts it in variable BpmStep
    text.str(FS.FloatToString(F.FFloat(Bpmstep)))
    waitcnt(5_000_000 + cnt)  '
    text.out($00)
  Comm.tx(214)           'this transmits for start number of 214
  Repeat go from 0 to 60        'this sets the range of memory locations I want to step through
    Comm.tx(Fx[noparse][[/noparse]go])     'this transmits that same memory range one byte at a time
    waitcnt(500 + cnt)  '1ms   'this waits 1ms to let receiver catch up.
 
  waitcnt(500_000 + cnt)

·

Mike G · 2010-07-02 13:00

Your transmit code is not syntactically correct. This should work better.

CON
    _clkmode = xtal1 + pll16x
    _xinfreq = 5_000_000

VAR
  byte  command 
    
 
obj
  PST        :"Parallax Serial Terminal"


PUB Main

  PST.StartRxTx(31, 30, 0, 57600)
  waitcnt(cnt+clkfreq/8)
  
  repeat
    waitcnt(cnt + clkfreq/2) 
    pst.Str(String("just a string"))
    pst.NewLine 
    pst.Dec(123)
    pst.NewLine

The Propeller receiver will need to parse the incoming string and determine the beginning and end of the data. For example, the code above transmits the following byte stream.

6A 75 73 74 20 61 20 73 74 72 69 6E 67 0D 31 32 33 0D

The "0x0D" marks the end of each data element.
6A 75 73 74 20 61 20 73 74 72 69 6E 67 = just a string
31 32 33 = 123

This is basic serial communications and ASCII.

Mike G · 2010-07-02 13:06

hello world <cr>
123.456 <cr>

68 65 6C 6C 6F 20 77 6F 72 6C 64 0D 31 32 33 2E 34 35 36 0D

koze85 · 2010-07-02 16:09

Ok thanks all for replying i am very close now and i think it doesnt have much work now

This is the code for the transmitter propeller

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000
VAR

obj
comm        :"FullDuplexSerialPlus"
  F     :       "FloatMath"
  FS    :       "FloatString"
Pub Transmit |go, bpmstep

comm.Start(14, 15, 0, 115200) 'Connect to the other propeller
 
 
Repeat
 Comm.tx(214)
 Repeat go from 0 to 24        'this sets the range of memory locations I want to step through
    Comm.tx(Fx[noparse][[/noparse]go])     'this transmits that same memory range one byte at a time
    waitcnt(500 + cnt)  '1ms   'this waits 1ms to let receiver catch up.
 
DAT

FX byte "This is a line of text.",0

And this for the receiver propeller with monitor

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000
VAR
word       Fx[noparse][[/noparse]24]
obj
  comm        :"FullDuplexSerialPlus"
  text  :       "tv_text"
Pub Receive |go
text.start(20)                  'start tv object in pins 20,21,22,23
comm.Start(15, 14, 0, 115200)   'Connect to the other propeller
repeat
 If Comm.rxtime(1) == 214       'signal triger from the other propeller
  Repeat go from 0 to 24        'get range of memory 22 characters + terminating string
   Fx[noparse][[/noparse]go] := Comm.rx            'Set array of charactes in buffer
   Fx[noparse][[/noparse]23] :=$00                 'Terminate the string
 text.str(@Fx)            'Print the string
  waitcnt(5_000_000 + cnt)      'pause for a bit
  text.out($00)                 'erase the screen

I do receive the screen but i can always display one character... Like this the code display the "T" character of the string.·If·instead of text.str(@fx) if i put text.str(@fx[noparse][[/noparse]1]) i will get the "h"

What i should do to display the whole string??????

Oldbitcollector (Jeff) · 2010-07-02 16:18

I'm not sitting at a propeller to test this, but while not add this to your repeat loop?

text.str(@fx[noparse][[/noparse]go])

OBC

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koze85 · 2010-07-02 17:22

Ok i found the error Fx must be declared as byte...

everything is fine now for one string...When i try to send a second one only the second one shows up any ideas?

koze85 · 2010-07-02 17:50

This is the code of the transmitter

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000
VAR
BYTE name1[noparse][[/noparse]25]
BYTE name2[noparse][[/noparse]25]
obj
comm        :"FullDuplexSerialPlus"

Pub Transmit |go, bpmstep,sl, string1,string2

comm.Start(12, 13, 0, 115_200) 'Connect to the other propeller
 
 
Repeat
 
 string1:=string("String1")
 string1:=string("String2")

 sl := STRSIZE(string1)
 Comm.tx(210)
 BYTEMOVE(@name1,string1,sl)
 Repeat go from 0 to 24        'this sets the range of memory locations I want to step through
    Comm.tx(name1[noparse][[/noparse]go])     'this transmits that same memory range one byte at a time
    waitcnt(500 + cnt)  '1ms   'this waits 1ms to let receiver catch up.
 
 sl := STRSIZE(string2)
 
 Comm.tx(211)
 BYTEMOVE(@name2,string2,sl)
 Repeat go from 0 to 5        'this sets the range of memory locations I want to step through
    Comm.tx(name2[noparse][[/noparse]go])     'this transmits that same memory range one byte at a time
    waitcnt(500 + cnt)  '1ms   'this waits 1ms to let receiver catch up.

And this from the receiver

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000
VAR
byte       Fx[noparse][[/noparse]26]
byte       Fx1[noparse][[/noparse]26]
obj
  comm        :"FullDuplexSerialPlus"
  text  :       "tv_text"
Pub Receive |go
text.start(20)                  'start tv object in pins 20,21,22,23
comm.Start(14, 15, 0, 115_200)   'Connect to the other propeller
repeat
 

  If Comm.rxtime(1) == 210       'signal triger from the other propeller
   Repeat go from 0 to 22        'get range of memory 22 characters + terminating string
    Fx[noparse][[/noparse]go] := Comm.rx            'Set array of charactes in buffer
    Fx[noparse][[/noparse]25] :=$00
 
 go:=0
  If Comm.rxtime(1) == 211       'signal triger from the other propeller
   text.out($0D)
   Repeat go from 0 to 24        'get range of memory 22 characters + terminating string
    Fx1[noparse][[/noparse]go] := Comm.rx            'Set array of charactes in buffer
    Fx1[noparse][[/noparse]5] :=$00
                                 'Terminate the string

                                 'erase the screen

                                   'Terminate the string
 text.str(@Fx)                                          'Print the string
 text.str(@Fx1)
 
 

 waitcnt(5_000_000 + cnt)      'pause for a bit
  text.out($00)

Screen only shows String2.... any ideas???

·

Transmit data between 2 propellers - please Help!

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