Communication Propeller - Basic Stamp

danielreis · 2010-10-29 12:05

Hi guys,

I need to communicate Propeller with Basic Stamp 2pe.
I was thinking about using 2 wires, one for data in and one for data out, but it didn't work. I also tried to put a 22k resistor in the pin of the BS2pe that I was using for receive data from the propeller, but it also didn't work.

I searched about it here in the forum, but I didn't find anything. I only found some threads about communication between 2 props or 2 BS.

Can anybody help me with it?

Thanks in advance!

Daniel Reis

Campeck · 2010-10-29 12:11

well for one the BSpe is a 5v system and the prop is a 3.3v system. did you use resistors in series with the comm lines?

JonnyMac · 2010-10-29 14:16

You can use half-duplex (since the Stamp can't TX and RX at the same time), open-true comms between the chips, with the serial line being pulled up to 3.3v on the Propeller side. Make sure that the boards have common ground. I've done this, it works fine because the TTL threshold on the Stamp is 1.5v so 3.3v is a solid "1". Each side will create a "0" bit by pulling the line to ground. "Open" comms only ever drives the line one way so you don't require a series resistor.

Campeck · 2010-10-29 18:44

oooh. Fancy! disregard my ignorance on communication between ucontrollers.

danielreis · 2010-11-04 11:29

Sorry about my delay to answer if it worked, but it's because this week was holiday here in Brazil, and I was travelling.

I tried to connect both without resistors, and in a common ground as you said, Jonny, but it didn't work.
I used the BS2_Functions OBJ from OBEX, and tried to use the following line, to make a test:

BS.serout_dec(tx, number, baudRate, polarity, bits)

I used 9600 baudRate, polarity inverted (0), 8 bits

In Basic Stamp, I used:

SERIN rx, baud, timeout, fail, [DEC rec]

baud = 16468, that is 9600, 8-bit, no parity, inverted

And when I try to run this, Basic Stamp can't receive anything from propeller.

Is there anything wrong with my code?

Martin Hebel · 2010-11-04 17:28

You did "Start" the BS2 object, correct?

It should work ok.
-Martin

$WMc% · 2010-11-04 17:53

danielreis wrote: »

Sorry about my delay to answer if it worked, but it's because this week was holiday here in Brazil, and I was travelling.

I tried to connect both without resistors, and in a common ground as you said, Jonny, but it didn't work.
I used the BS2_Functions OBJ from OBEX, and tried to use the following line, to make a test:

BS.serout_dec(tx, number, baudRate, polarity, bits)

I used 9600 baudRate, polarity inverted (0), 8 bits

In Basic Stamp, I used:

SERIN rx, baud, timeout, fail, [DEC rec]

baud = 16468, that is 9600, 8-bit, no parity, inverted

And when I try to run this, Basic Stamp can't receive anything from propeller.

Is there anything wrong with my code?

'
If you would post both codes used, It would make this a lot easier.
'
Its hard to tell witch is at fault if any, being one sided.
'
What is the BS2's full code?
'
This is very easy to do, You just need both Micro's on the same page!

danielreis · 2010-11-05 05:36

I tried it again, and it worked fine.
I tested both sending data from propeller to basic stamp and from BS to propeller, and everything worked fine.

Thanks everyone for the help!

I just didn't understand why the communication from propeller to BS uses polarity inverted and from BS to propeller uses it non-inverted. What's the reason?

Humanoido · 2010-11-05 06:30

danielreis wrote: »

I tried it again, and it worked fine.
I tested both sending data from propeller to basic stamp and from BS to propeller, and everything worked fine. Thanks everyone for the help! I just didn't understand why the communication from propeller to BS uses polarity inverted and from BS to propeller uses it non-inverted. What's the reason?

That sounds strange. Can you post the code and a drawing of your setup?

danielreis · 2010-11-05 07:31

First, from propeller to Basic Stamp:
Propeller:

CON

  'ClkFreq: 80 Mhz

  _XINFREQ = 5_000_000          'Adjust the frequency          
  _CLKMODE = XTAL1 + PLL16X     'Adjust the frequency

  rx = 0
  tx = 1
  baudRate = 9600
  polarity = 0
  bits = 8

OBJ

  bs :  "BS2_Functions"         'Basic Stamp 2 library

VAR

  byte number  

PUB start

  BS.start(31, 30)

  number := 0

  repeat
    BS.serout_dec(tx, number, baudRate, polarity, bits)    'send data to BS
    number++
    waitcnt(clkfreq + cnt)     '1 sec pause

BS:

' {$STAMP BS2pe}
' {$PBASIC 2.5}


tx  CON 0
rx  CON 1

baud   CON $4054
timeout CON 3000

number  VAR Byte

start:
    SERIN rx, baud, timeout, fail, [DEC number]          'receive from propeller
    DEBUG CR, "Test ok, received: ", DEC number       'show data received on screen
    GOTO start           'loop

fail:
    DEBUG CR, "Test failed, nothing received", cr
    GOTO start           'loop

Now, from BS to propeller:

Propeller:

CON

  'ClkFreq: 80 Mhz

  _XINFREQ = 5_000_000          'Adjust the frequency          
  _CLKMODE = XTAL1 + PLL16X     'Adjust the frequency

  rx = 0
  tx = 1
  baudRate = 9600
  polarity = 1
  bits = 8

OBJ

  bs :  "BS2_Functions"         'Basic Stamp 2 library

VAR

  byte number  

PUB start

  BS.start(31, 30)

  repeat
    number := BS.serin_char(rx, baudRate, polarity, bits)    'receive from BS; Tried to use "BS.serin_dec", but didn't work
    BS.serout_char(30, number, baudRate, 1, 8)       'show data received on screen
    waitcnt(clkfreq/2 + cnt)          '0.5 sec pause

BS:

' {$STAMP BS2pe}
' {$PBASIC 2.5}


tx  CON 0
rx  CON 1

baud   CON $54

number  VAR Byte

number = 0

start:
    SEROUT tx, baud, [DEC number]         'send data to propeller
    PAUSE 1000                     '1 sec pause
    number = number + 1
    GOTO start                    'loop

I connected TX pin of propeller(0) in RX of BS(0) and RX of propeller(1) in TX of BS(1), without resistors or anything else. I'm also using the same ground for BS and propeller

B_Bertoni · 2010-11-08 04:05

I'm with the same problem!

Humanoido · 2010-11-23 06:58

I have the system duplicated and working, however, the received result is truncated to one decimal place. Any idea how to format it to 3 integer places?

number := BS.serin_char(rx, baudRate, polarity, bits) 'receive from BS; Tried to use "BS.serin_dec", but didn't work
BS.serout_char(30, number, baudRate, 1, 8) 'show data received on screen

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Communication Propeller - Basic Stamp

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