Propeller Resets, Drawing too much power?

DiablodeMorte · 2008-03-26 04:26

Hello all,

I'm using a propeller(obviously) and trying to get it to control two servos(continious servos on the BoeBot). The servo commands are fairly simple(All forward, all backward, and all stop) but when I send them, every so often, the propeller resets right when I send a command. Is the transition from all forward to all stop or all backward simply too much for the little thing? I thought the Servo32v3 was supposed to protect against such a situation. Suggestions?


            if serialPacket == $31 'A 1, ie, forward
              'Forward
              waitcnt (cnt+125_000)
              'outa[noparse][[/noparse]18..23]~
              'outa[noparse][[/noparse]16..17]~~
              SERVO.Set(srvRight,1000)
              SERVO.Set(srvLeft,2000)
            elseif serialPacket == $32 'A 2, ie, stop
              'Stop
              waitcnt (cnt+125_000)
              'outa[noparse][[/noparse]16..18]~
              'outa[noparse][[/noparse]19..20]~~
              'outa[noparse][[/noparse]21..23]~
              SERVO.Set(srvRight,1500)
              SERVO.Set(srvLeft,1500)
            elseif serialPacket == $33 'A 3, ie, backward
              'Backward
              waitcnt (cnt+125_000)
              'outa[noparse][[/noparse]16..21]~
              'outa[noparse][[/noparse]22..23]~~
              SERVO.Set(srvRight,2000)
              SERVO.Set(srvLeft,1000)
            else
              'Stop
              waitcnt (cnt+125_000)
              'outa[noparse][[/noparse]16..18]~
              'outa[noparse][[/noparse]19..20]~~
              'outa[noparse][[/noparse]21..23]~
              SERVO.Set(srvRight,1500)
              SERVO.Set(srvLeft,1500)

Full Code Attached

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parts-man73 · 2008-03-26 04:36

Simply, Yes

You are drawing too much power and the Propeller is resetting itself due to Brown-out.

I had that same power when running off AA batteries, especially Dollar Store AA batteries. I mostly ran my Propeller powered Boe Bot while plugged into a Wall Wart power supply, but that limited it's range to within 6 feet of the wall outlet.

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uController.com - home of SpinStudio - the modular Development system for the Propeller

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DiablodeMorte · 2008-03-26 15:11

I'm actually connected to the wall, my powersupply must be too weak. Thanks for the confirmation of why it was doing that.

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Current Projects:
Robot Control Via Skype API - Dev Stage(50% Complete) - Total(25%)
Robot Localization Via Xbee's - Research Stage
IR Tracking with Propeller - Research Stage

Paul Baker · 2008-03-26 16:41

It may be a situation where it's enough to supply the average current, but not the peak current. You need to have around 1/2 Amp spare capacity for every servo you are running, this means your supply should be capable of putting out 1.5A or more.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Dgswaner · 2008-03-26 19:45

I had the same problem, running some servos and sensors from the prop. I didn't trouble shoot it but I figured that it was wire size or battery brown outs, now my Prop runs on it's own battery and I swapper out for bigger main battery connections and all is well in robo land!

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DGSwaner

jazzed · 2008-03-26 20:04

Activating N servo's at a time can cause deadly current spikes that can cause reset regardless of how big your power supply.

Two servo's should not suck too much current, but just in case as a general rule, you should provide some delay between servo settings to avoid current spikes associated with multiple servo movement. Another approach is "easing into" the desired value.

I tried servo32 as well, but still faced the spike issue with more than a few servos; I would enjoy seeing a working example of this with many servos. An alternative is Servo4.spin in the object exchange. I'm using it successfully with 4 servos (2 servos per cog) for a platform stabalization application. I Haven't tried a Prop BoeBot yet -- maybe later.

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Propeller Resets, Drawing too much power?

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