VSS VDD servo problems. Vss Vdd short causes reset?!
mporter
Posts: 2
Greetings.· I am a newbie, so· forgive me if this is a silly question:
I recently purchased a Parallax mini servo.· All I am trying to do at this point is get my BS2 to make the servo move.· Following instructions on the parallax site, I created a circuit where I connected two (yes, the correct two) of the servo leads to VSS and VDD and the other to p0 on my BS2.· I copied·some code from the parallax site that shows how to send a "PULSOUT 0,temp" to the pin.· However, when I try to compile and run, the stamp editor (v2.2.6) cannot find my stamp.· I can detach VSS, and am able to complie and run, and then re-plug in VSS, but the Servo does not move.· Also, it seems like my program freezes, and restarts when I unplug VSS.·
I put debug statements in my code, and that·seems to be working fine.· I also put an LED off of PIN0 and was able to verify that I am, in fact, getting a slight pulse out of·pin0.· I have·also tried·using other pins too (P4).
I am using a base board that I got out of a Predko book.· I have verified that I have 5v across VSS and VDD.· Other code on the stamp seems to work fine, provided that I don't directly connect·VSS and VDD.
Interestingly, I have also been able to get the stamp editor to find the stamp if I wire the servo like this:· VSS -> LED -> Servo -> VDD, or even without the servo if I do something like this:·VSS -> LED -> VDD, or VSS -> 470Ohm Resistor -> VDD.· I have been kicking around the idea of using an LM358 to try and isolate VSS/VDD from the servo, but honestly, I am not really sure I know what I am doing, and it just doesn't feel like I should need to do that!
I am using a brand new 9 volt battery to power my board.· And, my board uses a simple serial cable connection.
Is my stamp fried?· (Searching on the internet has lead me to start thinking that a voltage regulator on the BS2 might be destroyed.)·
Is my servo fried?
Any help, ideas, or general comments·would be greatly appreciated.
Thanks!
mporter.
I recently purchased a Parallax mini servo.· All I am trying to do at this point is get my BS2 to make the servo move.· Following instructions on the parallax site, I created a circuit where I connected two (yes, the correct two) of the servo leads to VSS and VDD and the other to p0 on my BS2.· I copied·some code from the parallax site that shows how to send a "PULSOUT 0,temp" to the pin.· However, when I try to compile and run, the stamp editor (v2.2.6) cannot find my stamp.· I can detach VSS, and am able to complie and run, and then re-plug in VSS, but the Servo does not move.· Also, it seems like my program freezes, and restarts when I unplug VSS.·
I put debug statements in my code, and that·seems to be working fine.· I also put an LED off of PIN0 and was able to verify that I am, in fact, getting a slight pulse out of·pin0.· I have·also tried·using other pins too (P4).
I am using a base board that I got out of a Predko book.· I have verified that I have 5v across VSS and VDD.· Other code on the stamp seems to work fine, provided that I don't directly connect·VSS and VDD.
Interestingly, I have also been able to get the stamp editor to find the stamp if I wire the servo like this:· VSS -> LED -> Servo -> VDD, or even without the servo if I do something like this:·VSS -> LED -> VDD, or VSS -> 470Ohm Resistor -> VDD.· I have been kicking around the idea of using an LM358 to try and isolate VSS/VDD from the servo, but honestly, I am not really sure I know what I am doing, and it just doesn't feel like I should need to do that!
I am using a brand new 9 volt battery to power my board.· And, my board uses a simple serial cable connection.
Is my stamp fried?· (Searching on the internet has lead me to start thinking that a voltage regulator on the BS2 might be destroyed.)·
Is my servo fried?
Any help, ideas, or general comments·would be greatly appreciated.
Thanks!
mporter.
Comments
The "Robotics with the BOE-Bot" book has a diagram which may be·helpful.
I attached a copy of the page for you.
Note that only the black wires of the servos are common.
·· I don't know about this board you're using or where it gets its Vdd from, but if it's coming from the BASIC Stamp 2 Vdd pin you're drawing far too much current from that pin with even one servo connected.· You cannot drive servos from the BS2 Vdd pin.· You must have a dedicated regulator, such as our BOE has, or you should use Vin, although that is not recommended with a 9V battery.· By the way, a 9V battery won't have the current capacity to run a servo very long before it's too low to power even the BASIC Stamp.· Take care.
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Chris Savage
Parallax Tech Support
Miles.