interfacing a RC receiver.

agfa

is there a recomended method to interface a RC receiver to the BS2?· currently i have the servo output·to the I/O via a 1k resistor, this method works but i occasionally get an input value (pulsin) out of its normal range.

Mike Green

You're using the recommended method. The resistor can be anything from about 220 Ohms to over 1K and is there only to protect the BS2 I/O pin from programming errors where the I/O pin is accidentally made an output opposite in state to the RC receiver's output. The RC receiver might actually be putting out pulses out of range. A real servo would ignore them. It might also be noise although the resistor should help suppress that. If you're not already doing it, you could use a twisted pair wire between the receiver and Stamp with the other wire connected to ground at one end.

agfa

thanks Mike.· i'll try the twisted pair.

RonP

Hello all,

Quick question I am in the middle of a project that requires and RC receiver connected to a BS2. I have been searching for info. I have successfully read the pulses. My question, the last sentence of this post talks about a twisted pair between the receiver and the stamp is that done to reduce noise or protect the circuit should the stamp pin turn into an output or both. First time I have seen this example. And for clarification signal pin on RX would have two wires connected one of them going to the stamp pin the other to a common ground? Would I still use the series resistor?

Mike Green wrote: »

You're using the recommended method. The resistor can be anything from about 220 Ohms to over 1K and is there only to protect the BS2 I/O pin from programming errors where the I/O pin is accidentally made an output opposite in state to the RC receiver's output. The RC receiver might actually be putting out pulses out of range. A real servo would ignore them. It might also be noise although the resistor should help suppress that. If you're not already doing it, you could use a twisted pair wire between the receiver and Stamp with the other wire connected to ground at one end.

Thanks

Ron

Mike Green

The use of a twisted pair of wires is just for protection from externally induced noise. You still need the series resistor to protect the Stamp I/O pin in case it's accidentally set to output mode. The ground wire of the twisted pair is connected at one end or the other to a common ground. You could connect it to Vss on the Stamp end or to the ground on the R/C receiver end.

RonP

Understood.

Thanks for the quick reply Mike G.

Ron