What range of pulses does an RX31 reciever output

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Andrew_Hibberd
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What range of pulses does an RX31 reciever output

Post by Andrew_Hibberd »

Has anyone linked an oscilloscope to an rx31 receiver to see what maximum and minimum pulse lengths it gives (this may even be TX dependent)? Currently Anticide is a lot slower than on paper and I think it is because I have my code looking for 1->2ms, however if the RX31 only gives 1.1->1.9ms I loose 20% of the top speed. If no one has done this I will try and have a go tomorrow evening and post the results.
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Andrew_Hibberd
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Re: What range of pulses does an RX31 reciever output

Post by Andrew_Hibberd »

I had a go with a scope, it looks like I am not getting full speed out of my motors on Nom and Anticide. The scope was not perfect however the range measured was 1.08 -> 1.92ms for the full range of the throttle on the Rx31. If this is accurate then I should be able to get almost 20% more speed out of the robots. Anyone else done similar tests on other RXs?
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ajw
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Re: What range of pulses does an RX31 reciever output

Post by ajw »

Thanks for the info Andy. I've used 4 & 6 channel Orange RXs and my results were very similar 1.112->1.908ms. I'm not sure on the accuracy since I used a simple logic tool rather than a scope but the results were repeatable (whether they were wrong or right...) This leaves me with a centre position of 1.51ms for equal servo throw since trims did not effect end points. This was using a cheap MLP4DSM transmitter but also confirmed similar results using a DX6i with standard end limits. Only just crossed my mind that the throttle channel must work slightly differently to the aileron/elevator since end points on the throttle are effected by trims.
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peterwaller
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Re: What range of pulses does an RX31 reciever output

Post by peterwaller »

The pulse lengths are generated in the Transmitter the receiver just splits them up into seperate channels.
The pulse lengths you are measuring sound around normal.
What I do to ensure I get full speed is to use the pulse length to access a table for the motor speed.
My timer checks how different the pulse is from 1.5 ms giving a value between 0 and 24 and this is used to access the speed value in the table below.
The direction of the motor is determined by the pulse being longer or shorter than 1.5ms.
By having more than one value of 0 gives a bit of a deadband to avoid the motors creeping when stopped and by have several values at 255 you can always ensure full speed .
DR_TABLE:
.db 0,0
.db 10,20
.db 30,40
.db 60,80
.db 100,120
.db 140,160
.db 180,190
.db 200,210
.db 220,230
.db 240,250
.db 255,255
.db 255,255
.db 255,255
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