Trouble with the Pololu Motor Controllers

neoteric · 2006-02-23 16:39

I am having problems with getting my motors to stay on.· I have tried both of thier dual serial controllers.· Mini, and kit.· I have tried with both 12V motors, and small 3 volt motors.· Both with seperate power supplies.· In the code attached, I debug a loop to the screen.· The motors should run to 1000, but only get to about 300 ish.· Both controllers get warm.· Is it my code?· I posted to pololu's support forum, but nobody seems to be answering over there.· (I am spoiled by the support I have gotten here I guess.)·I got the micro serial motor controller here, so felt it was ok to ask here.· I will buy the Parallax controller when it is available, but my robot wants to move before then....

'   {$STAMP BS2}
'   {$PBASIC 2.5}
' -----[noparse][[/noparse] I/O Definitions ]-------------------------------------------------
Sout CON 3    'serial line ,Pololu motor controller
Reset CON 4   'reset line  ,Pololu motor controller
' -----[noparse][[/noparse] Constants ]-------------------------------------------------------
#SELECT $STAMP
  #CASE BS2, BS2E, BS2PE
    T1200       CON     813
    T2400       CON     396
    T4800       CON     188
    T9600       CON     84
    T19K2       CON     32
    TMidi       CON     12
    T38K4       CON     6
  #CASE BS2SX, BS2P
    T1200       CON     2063
    T2400       CON     1021
    T4800       CON     500
    T9600       CON     240
    T19K2       CON     110
    TMidi       CON     60
    T38K4       CON     45
  #CASE BS2PX
    T1200       CON     3313
    T2400       CON     1646
    T4800       CON     813
    T9600       CON     396
    T19K2       CON     188
    TMidi       CON     108
    T38K4       CON     84
#ENDSELECT
SevenBit        CON     $2000
Inverted        CON     $4000
Open            CON     $8000
Baud            CON     T9600
' -----[noparse][[/noparse] Variables ]-------------------------------------------------------
MLFwd CON 5   'l forward'
MRFwd CON 7   'r forward'
MLRrv CON 4   'l reverse
MRRrv CON 6   'r reverse'
'SEROUT Sout, Baud, [noparse][[/noparse]$80,2,2]  'used to set controller
x VAR Word     'loop variable
' -----[noparse][[/noparse] Init  }---------------------------
DEBUG "reset"
GOSUB resetcontroller    'Reset_SMC:
' -----[noparse][[/noparse] Main  }---------------------------
Main:
DEBUG "forward"
FOR x= 1 TO 1000
GOSUB  Forward
DEBUG DEC x," - "      'gets to around 300 ish and motors stop! 3V or 12V motors
NEXT
DEBUG "end"
SEROUT SOut, Baud, [noparse][[/noparse]$80, 0, MLFwd,0]   'stop controller  WORKS
SEROUT SOut, Baud, [noparse][[/noparse]$80, 0, MRFwd,0]
GOSUB resetcontroller
END
' -----[noparse][[/noparse] Subs  }---------------------------
Forward:
SEROUT SOut, Baud, [noparse][[/noparse]$80, 0, MLFwd,127]
SEROUT SOut, Baud, [noparse][[/noparse]$80, 0, MRFwd,127]
PAUSE 20
RETURN
resetcontroller:
HIGH Serout
LOW Reset
PAUSE 1000
HIGH Reset
PAUSE 1000
RETURN

·I really appreciate the help from anyone who can help me!

Post Edited (neoteric) : 2/24/2006 8:50:34 PM GMT

Steve Joblin · 2006-02-23 17:04

I would first confirm that your set up and parts are functioning... have you created a simple program to test your set-up? Something like this is a good test:

'{$STAMP BS2}
SPEED var byte
RESET_DSMC con 15
output 14

DEBUG CLS
DEBUG "Reset Controller", CR

Low RESET_DSMC
pause 10
High RESET_DSMC

DEBUG "Ramp Up Motors Forward", CR
for SPEED = 0 to 127
serout 14,32,[noparse][[/noparse]$80,0,1,SPEED]
pause 50
serout 14,32,[noparse][[/noparse]$80,0,3,SPEED]
next

pause 1000

DEBUG "Ramp Down Motors Forward", CR
for SPEED = 127 to 0
serout 14,32,[noparse][[/noparse]$80,0,1,SPEED]
pause 50
serout 14,32,[noparse][[/noparse]$80,0,3,SPEED]
next

pause 4000

DEBUG "Ramp Up Motors Reverse", CR
for SPEED = 0 to 127
serout 14,32,[noparse][[/noparse]$80,0,0,SPEED]
pause 50
serout 14,32,[noparse][[/noparse]$80,0,2,SPEED]
next

pause 1000

DEBUG "Ramp Down Motors Reverse", CR
for SPEED = 127 to 0
serout 14,32,[noparse][[/noparse]$80,0,0,SPEED]
pause 50
serout 14,32,[noparse][[/noparse]$80,0,2,SPEED]
next

end

neoteric · 2006-02-24 17:20

Steve,
I previously wired it up exactly as described in the docs, and ran the code you suggested. Worked fine. I have since wired a lot more to the breadboard, and moved the hookups from pins 15 and 14 to pins 3 and 4. Also, I have sent the reconfig to the PSMC to change the motor numbers. ('SEROUT Sout, Baud, [noparse][[/noparse]$80,2,2] 'used to set controller) (Set motors to 2 and 3)

I will try to change them back, and test again. I was hoping someone could review my code, or let me know if they think I have a heat problem. I think its a heat issue, that the controllers just cannot take sustained motor use. I have added a fan, that blows right on the PSMC, but to no avail. I am having the same problem with both types of Pololu dual serial controllers.
I may be missing something.....

PS, I have posted on the Pololu website, and left 2 emails there.· No response.

Steve Joblin · 2006-02-24 18:00

why do you think it is heat related? how hot is the unit? try putting a big loop around my pogram and let it cycle through ramping up and down 50 or 60 times... does it still work? try writing a simple program that sends a command to run the motor at "half speed" and let it go for a while... If these two things work, then you have isolated your issue down to "bad code". i will try to review your code this weekend, but I am quite a nubie and do not have the programming accumen that you may require.

NickelPlate · 2006-03-25 04:47

I don't think it's your code because I had the same problem with mine. Even with really small motors that didn't draw anywhere near the rated current of their device, it would just stop working after a short while and get really hot. I tried slow speeds, medium speeds, high speeds, gradual ramp ups. I used a Stamp, PIC and an AVR with no effect.

They sent me a replacement and it did the exact same thing, I tried two different motors, two different power supplies and even a battery, no help. After much troubleshooting, measurements and lengthy discussions with their tech support on the issue, I got tired of gnashing my teeth trying to figure out why their controller didn't work and just canned it.

When I asked for a refund, they (Pololu) refused and accused me of breaking it and not knowing what I was doing. Nice huh? Consequently, I no longer buy anything from them.

My advice is to just get Parallax's HB-25, if Parallax designs something, you can bet it will work as advertised.

Regards,

NP

Post Edited (NickelPlate) : 3/25/2006 5:04:33 AM GMT

neoteric · 2006-03-25 15:10

I did one better.· I bought thier larger motor controller, too.· Neither worked.·

Finally Parallax shipped thier motor controllers.· Hooked them up and had the motors working within 5 minutes.· They are great.

I posted on thier forum.· They never answered.· I had to send 5 emails to Pololu to get a bad answer,·finally got an·answer after·I specifically said:" could you answer my post on the forum."· The answer they gave was incorrect.· I called them, they never called back.· I'm surprised that Parallax offers thier products.

I'm writing it up to tuition, and a·punitive fee for not having the patience to wait for the Parallax product.·· ·Lesson learned: Parallax quality, Parallax support.·

Steve Joblin · 2006-03-25 16:08

Sorry to hear that you had a bad experience with them... I had brought one of their first Servo Controller products when they were just getting started... the support was actually quite good (which is why I thought that Parallax was carrying thier product)... based on your experience, it does not seem that they are providing the same kind of support that they used to... that is a shame!

MikeK · 2006-03-26 05:05

I had trouble with one of the P*u serial motor controllers. By trial and error I discovered that it would work if I left the Reset line floating (I use a momentary contact switch to briefly pull it low to reset the controller). Not a great solution, but it's too small to use as a doorstop.

Mike

merlin · 2006-05-30 14:10

I have one Pololu Motor Controller connected to two motors and I have experimented a lot of problems due some erratic behavior. I have replaced the unit with another unit and the behavior is the same.
I have tried to post on Support Pololu forum, so I have registered on the website two days ago...until now I didn't receive the confirmation to aprove my registration, so I can't even post my problems on their site.
I have excelent experiences with several others products from Parallax, so it is a real surprise to find here so bad products and so bad support from Pololu, because I assumed Pololu was valited as a good supplier by Parallax.
I reccomend to try another option than Pololu when you need a motor controller. Bad support must have cost in the users preferences.

best regards

merlin

Craig N · 2006-06-20 02:21

OK, so I just spent a number of hours experimenting with the Pololu motor controller, and researching as much as I could on the web. Its behavior appears *really* erratic, mainly due to the temperature cutoff switch. With the Tamiya 70097 twin-motor gearbox kit and either 4 AA batteries in series or a 3.6V 1500 mA cordless phone battery as the motor input, the unit cuts off quickly (and variably, which was at first confusing.) If I use 2 AA batteries in series, the unit works. So, for very low power apps, the Pololu motor controller should work, but it's clearly limiting. I've ordered 2 HB-25s, QED. Just an FYI for this thread, which was helpful in figuring out the temperature cutoff problem.

The next robot I build will have stepper motors

Cheeto · 2006-06-26 19:42

Anything ever come of this ? I bought the little controller before i saw this thread and I can't make it do anything reliable

I used this to configure it
SEROUT 14,84,[noparse][[/noparse]$80,2,0]
pause 100
Low 14
Pause 1
High 14
pause 100
SEROUT 14,84,[noparse][[/noparse]$80,0,1,75]

And for some awesome reason that makes both motors spin !! Even though it should be configured for 2 motors 0 and 1 !!! Oh then both motors just stop spinning, just for the hell of it. It's awesome, I have been playing with it for 3 hours now and never made it do one thing reliable except the same crazy unknown behavior. I am using it with the Tamiya 70097, with both motors out to give less resistance.

Post Edited (Cheeto) : 6/26/2006 8:10:09 PM GMT

Cheeto · 2006-06-26 21:05

Pololu put the H-Bridge Chip in backwards, so the Logic side of the chip was getting +15V and the Motor Supply was getting +5V hooray !!! I bought the damn thing premade because it said they were tested before being shipped out, I call bull(expletive).

edit: they are sending me another SN754410NE yeah!! lets see if it works after that

Post Edited (Cheeto) : 6/26/2006 9:14:38 PM GMT

Trouble with the Pololu Motor Controllers

Comments