Esc problem

[teemodel]

I'm trying to make a timer for u-control plane using 08M and esc for throttle control. Esc will not run motor at full power. Seems to top out about 175 instead of 225. Using a transmitter and receiver will run the motor full speed. I have tried setting the top and bottom of the esc travel with code but it doesn't seem to work. Help.
Teemodel

 

[Adamey]

Can you post a sample of your code? Only way anyone can really see what's going on and where any potential problems might be. Also, what are you doing in between sending the servo command? If there's too much code executing, then maybe the time between servo pulses is greater than 20ms, which is what most RC servos/ESC's expect.

 

[teemodel]

esc

here is a snippet:

Init: servo 2,75
pause 1000
for b1 = 75 to 225 step 25
servopos 2, b1
pause 1000
next b1
end


Does that help

 

[Adamey]

That looks to me like it should work fine. Where is the power for the ESC coming from and what is powering your PICAXE? Perhaps there is some electrical noise causing problems.

Do you have access to a scope? You could monitor your PICAXE output with and without the ESC connected to see if you're getting the 2.25ms pulse width on your output pin.

 

[Technical]

You are using steps of 25, so only testing values ...175 - 200 - 225

Try using, say, a value of 190 and se if that is better than 175. The PICAXE-08M pulses will not be exactly the same as a tx-rx setup, so some experimetation may be required to find the 'best' top value.

 

[westaust55]

No all RC servomotors use the nominal range 75 to 225.
I have some that operate over the range 60 to 200.
Any setting outside that range is ignored.

Try stepping up one step at a time from 175 to 230 and watch for when the servomotor horn stops moving. Same can be done for the lower limit.
Thena djust yo9ur program to use the full range that the servo will accept

 

[BeanieBots]

The issue relates to an ESC not a hobby servo but you're probably onto the right issue.
Another potential problem with RC hobby ESCs is that some require a high and low rate initial pulse stream to initialise them so that they produce 0% to 100% throttle irrespective of 'stick' throw.
If it is such an ESC, then an initialisation sequence will be required prior to any attempt at using it after every power down.

 

[teemodel]

esc trouble

Well, I listened to all an tried the various suggestions. Put a servo in the circuit and could get response down to 40 or 45. Topped out at about 180 or so. Then put esc back in and would not initialize at that low a number so went back to 75. I had already tried a software reset to the throttle but gave it another try. This time it seemed to work when I changed the code slightly.
servopos 2,225
pause 3000
servopos 2,75
pause 2000
init:servo 2, 75
more code
I also think part of my problem is a lack of voltage to the motor. Its a 1380 KVA motor and only turning 6900 rpm. Using a two cell lipo. Got a lot of small wire footage doing testing.
The prompt expert advice from all is very much appreciated.
Bob