Reading smart motor data with db9 through max232

mechqueen

Hello,

I am not doing so well with this yet. I have a PTP
http://www.rayslogic.com/propeller/Products/PTP/PTP_Schematics.htm
And all I want to do is read velocity from a smart motor rs232 output.
The smart motor db9 is connected into a max32.
I have the gnd and 5v of out of the max232 coming into the board with the Q44 Propeller Parallax chip on it
going to V5 and Gnd. I also have the TX going to P4 and Rx Going to P5 on this board because my usb from my computer
is inserted into the board, so that takes care of my onboard tx rx going directly to the Q44 chip.

I have tried different UART commands. And this is my code for now which all it does is display the velocity text but I want to
know what is coming out of the tx of my db9, and read it back to the display for velocity.

Here is the code so far. Maybe over kill but a co-worker gave me quite a bit of code to start with which included
Xbee functions and numchuck info which I took out. I only want to read the velocity value coming out of of the db9 Tx port.

I just do not know what to do next. Any help steering me in the right direction would be helpful.

Thank you

Duane Degn

mechqueen wrote: »

I also have the TX going to P4 and Rx Going to P5 on this board because my usb from my computer
is inserted into the board, so that takes care of my onboard tx rx going directly to the Q44 chip.

I haven't looked at the code yet but I wanted to warn you about using 5V logic signals with the Propeller. You need at least a 3.3K resistor in series on the rx line from the MAX232 chip.

I'll take a look at the code a bit later if no one else beats me to it.

mechqueen

Yes, thank you. I already do have a resistor in series with the rx line which is bringing my voltage down to 3.30.

Duane Degn

I haven't tested this but it should let you see any non-printable characters.

CON

  _clkmode = xtal1+pll16x
  _clkfreq = 80_000_000

 

CON
                                  'Note Clock Speed for your setup!!

    COM11_RX = 4
    COM11_TX = 5

    COM12_RX = 31
    COM12_TX = 30

    BAUD_RATE = 9600
    

    
OBJ
  uart1     : "FullDuplexSerial"
  uart2     : "FullDuplexSerial"

PUB Main


  uart2.start(COM11_RX, COM11_TX, 0, BAUD_RATE)
  uart1.start(COM12_RX, COM12_TX, 0, BAUD_RATE)

  repeat
    result := uart2.rxCheck
    uart2.str(string(11, 13, "Press Any Key"))
    waitcnt(clkfreq / 2 + cnt)
  while result == -1  

  uart2.tx(16)  ' clear screen
  uart2.tx(1)   ' home
  uart2.str(string(11, 13, "Data Logger v.1"))
  uart2.tx(11) ' clear end of line
  uart2.tx(13)

  'echo everything out
  repeat
    result := uart1.rx
    SafeTx(result)
     

PUB SafeTx(character)

  case character
    13:
      FramedHex(character)
      uart2.tx(character)
    33..126:
      uart2.tx(character)
    other:
      FramedHex(character)

PUB FramedHex(character)

  uart2.tx("<")
  uart2.tx("$") 
  uart2.hex(character, 2)
  uart2.tx(">")

mechqueen

Oh wow. Thank you. I will see how this works and post back.

Duane Degn

I just noticed a mistake. That's what I get for not testing it. I'll fix in a few minutes.

Duane Degn

I fixed the embedded code above and I've attached the corrected Spin file to this post.

I still haven't tested the code but this version has a better chance of working.

Cluso99

I have the gnd and 5v of out of the max232 coming into the board with the Q44 Propeller Parallax chip on it
going to V5 and Gnd.

I do hope you are using 3V3 on the propeller chip???

I see the schematic shows all 4 sets of power and ground are connected and with bypass capacitors. I presume you have a propplug to program your propeller (It appeared to be a separate connector on the schematic. If you build your own propplug you will need the transistor reset circuit. I like a 10K pullup on the prop RST pin as it helps to prevent noise causing an unwanted reset.

kicadguru

Is there any difference between using a modern MAX232 variants vs the older ones. The new ones all point to a datasheet that is over 20 years old! see attached PDF file. I'm guessing it's just to conform to RoHS.

Circuitsoft

You probably should use a max3232, which is made for 3.3v instead of 5v.