Motor MIND B with BSpx module

Philip Verspreeuwen · 2007-01-08 13:11

Hello,

Being complete new to the roboticsworld,·I have a probabily quite easy question. I want to use the motor mind B just for controlling a motor (no tach or brake function). I thought a command like SEROUT 1,1646 [noparse][[/noparse]85,3,127] would make the electrical engines turn at half speed. I also tried it with hexadecimal values, but nothing happens. The Motor mind B receives a valid signal because the green led blinks. After a few hours of search, I'm out of tricks. I'm going to use the SETDC_DIR command. If anyone can give me the code lines he uses for this, please do.

My kindest regards

Bill Chennault · 2007-01-08 13:43

Philip--

Here is what I used . . .

http://www.parallax.com/dl/docs/prod/motors/MotorMindbMan.pdf

Read the whole thing, but what you really want is the schematic at the bottom of page 10. Works like a charm!

--Bill

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Philip Verspreeuwen · 2007-01-08 14:05

Thank you for the reply, but Ihave read the manual (a few times) but still nothing is coming out of the motormind... I think the problem is my software. All the rest seems OK. Can you just post me a basic command line I can run on the stamp? If it doesn't work, I will know something is wrong in my hardware.

Thank you very much for your help.

DaveG · 2007-01-08 14:25

Philip,

The Motormind spec sheet says the default baud rate is 2400 baud.

Your command SEROUT 1,1646 [noparse][[/noparse]85,3,127] specifies a baud rate of 600. The "1646" = 600 baud.

You might try changing the "1646" to "396", which is 2400 baud.

Dave

Philip Verspreeuwen · 2007-01-08 14:29

I'm using the BS 2px module. According to themanual the baud rate should be 1646. I tried 396, but then the microcontroller doesn't even blink anymore ...

DaveG · 2007-01-08 14:37

Philip,

Silly me. Just after I pushed the send key, I noticed my error. 1646 is correct.

You might try 18030(inverted) and see what happens.

Dave

DaveG · 2007-01-08 14:56

Philip,

If you are using two power supplies in your setup, the grounds should be connected together, i.e. you
need a "common" ground for the system.

Dave G

Philip Verspreeuwen · 2007-01-08 16:05

I use one powersource. So the ground should not be a problem.

The baud rate is correct to· because the green led on the motorcontroller B blinks when I send my information. I think there is something wrong with my last information. I send 85 for synchronisation, 8 for SETDC_DIR command and then -64 (or another deimal beteen +/-127). Is it possible I need to convert this to a hexadecimal or 2's compliment value? And do I need to specify the order of the bits? I tried the hexadecimal and 2's compliments conversion, but it still doesn't work.

Vern Graner · 2007-01-08 17:20

Philip Verspreeuwen said...
I use one powersource. So the ground should not be a problem. The baud rate is correct to because the green led on the motorcontroller B blinks when I send my information. I think there is something wrong with my last information. I send 85 for synchronisation, 8 for SETDC_DIR command and then -64 (or another deimal beteen +/-127). Is it possible I need to convert this to a hexadecimal or 2's compliment value? And do I need to specify the order of the bits? I tried the hexadecimal and 2's compliments conversion, but it still doesn't work.

THis is the code I used with a BSIIP to control a MMB:


' ************************
' * Conditonal Compile   *
' *************************************************************************
#SELECT $STAMP
  #CASE BS2, BS2E, BS2PE
    T2400       CON     396
    T4800       CON     188
    T9600       CON     84
    T19K2       CON     32
    T38K4       CON     6
  #CASE BS2SX, BS2P
    T2400       CON     1021
    T4800       CON     500
    T9600       CON     240
    T19K2       CON     110
    T38K4       CON     45
  #CASE BS2PX
    T2400       CON     1646
    T4800       CON     813
    T9600       CON     396
    T19K2       CON     188
    T38K4       CON     84
#ENDSELECT


' ************************
' * Constants            *
' *************************************************************************
   ' Motor Mind B Settings
    MMBpin          CON     8     ' Pin to which MMB is connected
    MMBsync         CON     $55   ' Serial com init
    MMBBaud         CON     T2400 ' Serial rate of MMB
    MMBstop         CON     0
    MMBlow          CON     38    ' low speed value
    MMBmedium       CON     75    ' medium speed value
    MMBhigh         CON     255   ' High Speed Value

' ************************
' * Set the motor Speed        *
' *************************************************************************
      SEROUT   MMBpin,MMBbaud,[noparse][[/noparse]MMBsync,3,MMBmedium] ' Set the MMB speed

The above code worked with both a MMB (original) and an MMB with the newer firmware. I dont have an MMBe to try it with though... Hope this helps.

Vern

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Philip Verspreeuwen · 2007-01-08 22:52

I needed something like this. It looks similar to what I made. But maybe I forgot semething. I will test it in two days. Thank you very much for the code. I can't wait to try it out.

Bill Chennault · 2007-01-09 00:09

Philip--

Take a look at Solutions Cubed, the manufacturer of the MMBe. This link has several programs that worked for me.

--Bill

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
You are what you write.

Motor MIND B with BSpx module

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