RC receiver to prop hookup

Shawna

Hey guys i have a spectrum dx6 receiver that i want to hookup to a prop. The pwm signal is 5 volts. Can i hook the signal wire straight to the input pins on the prop or do i need to put a 100 ohm resistor between the two.

Mike Green

Neither. If you hook the signal wire straight to the input pins on the Prop, you'll burn out the protection diode and maybe fry the Prop chip. A 100 Ohm resistor isn't big enough. You need to limit the current through the diode to 500uA. A 2.2K or larger resistor should be fine. (2.2K x 500uA = 1.1V, 5V - 3.3V - 0.6V = 1.1V)

Duane Degn

I don't know if you have code you intend you use already, but I modified someone else six pin RC rx code to use any six (or less) of the Prop's I/O pins (it originally on to be the lowest six pins). Here's the link to my version.

I generally use 10K ohm resistors with 5V inputs since it's a relatively common resistor value and the Prop doesn't have any trouble reading the signal with a 10K resister in series.

Shawna

Thanks for the replies.
Now if I send a pwm signal from my prop to an esc signal wire would I use a resistor for that also.
I have hooked the prop straight up to one for test purposes and it seems to work. Even though the esc is looking for a 5 volt signal.

localroger

You don't need the resistor running a 3.3V output to a 5V input. The main danger there is that some 5V inputs won't see 3.3V as logic 1, but if it's working you obviously don't have that problem.

Shawna

Thank You
Everything I worked with before the prop ran on 5V. It is taking some getting use to, a person just has to give a little more thought when building a circuit.

xanadu

Don't forget to snip the power lead coming off the rx channels to the prop, the battery/BEC is usually tied to every output on the rx so it should be signal and ground only going to the prop unless you want to power it from the rx.

Scope

If you're talking about modifying a 3-pin servo/receiver wire connector, then you don't literally have to "snip" the wires. I use a tiny flathead screwdriver (Whia makes decent tools in this category) and carefully pry up the plastic "finger" that helps hold the metal connector in the 3-wire housing then gently pull out the wire/connector from the plastic housing. Then I wrap the exposed metal connectors with a tiny strip of painters tape - "crimping" the tape a few mm from the end of the metal connector with the grippy part of needle nose pliers keeps the tape from coming undone - well used quad copter trick.

OR

You can connect the white (or lightest color - the signal wire) female connector with a male-male jumper to the breadboard

xanadu

Thanks Scope, I definitely could have used a better word than snip, like disconnect! Oops...