I have a four channel radio control receiver in a model. Channel four is an on/off servo channel. I am trying use it to trigger a soundtrack to play on the DFPlayer Mini. I know that I can do so using a Pololu RC switch with digital output between the servo and the DFPlayer but am trying to avoid the cost and complexity. Is there any way of a connecting them directly please?
Hi @Peter197296
Welcome to the forum!
Since your RC receiver outputs a PWM signal for the servo, and the DFPlayer Mini in standalone mode just needs a pin pulled low to play the next file, you can create a super simple interface using a low-pass filter and a transistor.
For that you’d need:
- 1 × 10kΩ resistor
- 1 × 1.1kΩ resistor
- 1 × 1µF capacitor
- 1 × NPN transistor (e.g., 2N3904 or similar)
You would wire it up in a similar fashion to below:
RC CH4 (PWM)
|
10kΩ
|
±—> to transistor base (via 1kΩ)
|
1µF
|
GND
Transistor:
- Base: from above
- Collector: DFPlayer IO1
- Emitter: GND
‘on/off servo channel’ is typically used to describe a channel in the transmitter, not the receiver, and means that the channel is a signal for the servo that is either on or off - that is, it is either sending PWM at zero value or at full value depending on a two-way switch. That’s not suitable for driving the player attached to the receiver without a PWM decoder, such as the Polulu device you mention.
Using that term for a receiver seems inconsistent - it would be either an on/off channel (which would work as a switch) or a servo channel. Do you have a reference for that receiver with a description of how that channel works?
Thanks Dan. I will give that a go.
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