toprudder

I have a Berg 7P receiver and the Castle Link programmer. I can't find any documentation regarding the programmable frame rate feature of the 7P receiver. The default is 50ms, and I can increase it in steps up to 80ms. When I set it to 80ms, I do notice a small increase in performance of the servos, but there is interaction between channels. IOW, when I move the ailerons right/left, sometimes the elevator and rudder will move several degrees. When I move the rudder left/right, sometimes one of the ailerons (channel 7) will move. When they do move, sometimes they jitter and not return to center right away. When I set the frame rate back to 50ms, the problem goes away. I have not tried changing the frame rate to other values yet.

Has anyone played with the frame rate on this receiver? Notice any symptoms like this?

Bob R.

rino

My Feedback: (121)

I have recently had the same issue and I am running Hitec 475 HB's. I also am having some problems on 6 volts.

XJet

I suspect that unless the frame-rate outputted by the receiver matches that at which the frames are received from the transmitter you're going to (at least) get a periodic "jitter" where the processor is busy trying to handle the incoming (from the transmitter) data at the same time it's attempting to assemble a set of pulses for the servos.

Although I have a 7P, I don't have the CastleLink software so I don't know exactly what the 50mS and 80mS parameters you mention are refering to -- but 80mS sounds *longer* and therefore *slower* than the default -- so why would you want to change it?

toprudder

I thought about that later, "ms" could not be right. My bad. The unit was "Hz" not "ms". 50Hz equals 20ms, 80Hz equals 12.5ms.

Part of my understanding of digital servos is that internally they increase the frame rate, increasing the pulses going to the motor to update the servo position. This improves holding torque. I was hoping to use this feature in the Berg 7P for that reason. I guess I need to try other frame rates to see if I can find a faster one than 50Hz that still works.

Like I said, I don't see this feature advertised anywhere, it is not mentioned anywhere that I can find.

XJet

Hertz (Hz) makes more sense. The average frame-length for most RC gear is arould 20mS which produces a frame-rate of 50 per second (50Hz).

Upping that frame-rate would (in theory) make your (non-digital) servos work better -- but as I mentioned, the poor old processor in the 7P will be running out of puff to be able to cope with the fact that it's busy receiving the data at 50Hz and trying to spit it out at 80Hz.

I suggest you just leave the setting at 50.

rino

My Feedback: (121)

I'm going to call Castle tomorrow and ask them about running on 6 volts. My JR receivers did fine on 6 with the same servos. I'm not sure why the 7P is getting the jitters though.

XJet

I haven't actually tried my 7P yet. I've got some 475 servos here and a 5-cell pack so I'll connect them up later and see if I get the same results.

blkbird68

My Feedback: (19)

I have run mine at 80Hz some just to play with it. I have not had any problems.

toprudder

How many channels are you using? I wonder if the number of channels used may affect it. I was also using an 8ch transmitter, maybe the extra received pulse is a problem. I have a 7ch transmitter I can try.

blkbird68

My Feedback: (19)

the radio I was using is an Airtronics Stylus (8channels) I was only using 6 of the Rx's channels.

rino

My Feedback: (121)

What kind of servo's are you running?

blkbird68

My Feedback: (19)

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