Hi Larry,
Well, Nathan does not know my circuits so he should not be making assumptions. If he would call me I could explain why this is a bad idea. Here it is in technical terms, I will try to summarize at the end. We use buffer ICs that have CMOS, high-impedance inputs so we do not load the receiver. You do not want an input to the buffer to float, so we put 10K resistors to ground on the wires (signals) that come from the receiver so that if you do not connect a pigtail to the receiver it will be pulled to ground. That means that the signal pin in the BIND plug will see a 10K resistor to ground. The receiver uses some value of resistor to pull the signal wire of the BIND plug up to Vcc, the operating voltage of the microprocessor in the receiver. When you put a BIND plug in the signal wire is pulled to ground and the microprocessor can read this and know its suppose to bind. Now, the big question is, what value of pullup resistor do they use? I have no idea, but unless its smaller than 1K (10 to 1 rule) then my 10K resistor can cause problems. The combination of the two resistors will cause the microprocessor to see a voltage on its bind sense pin that cannot be resolved as yes or no. I have always told people that the PowerExpander and PowerSystem receiver connections are ONLY meant to go in servo slots on the receiver. This is safe. Plugging one of our receiver leads into the battery input on a PCM receiver will put it into DSC if the receiver has DSC and plugging a receiver lead into a Spektrum or JR 2.4GHz receiver "may" cause it to bind.
So, basically the problem is this, while we do not short the signal wire to ground, we do pull it to ground using a 10K resistor. This may put the bind input to the microprocessor in a state it cannot resolve and it may or may not go into bind. I err on the side of safety.
Sorry for all the technical jargon but I wanted to lay it all out there. Technically, I like the way Futaba did their bind, I feel the pushbutton is a safer way. Please let me know if you have any more question.
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| Hi Robert,
I asked Horizon support about what you said, not to connect a power lead from your power expander sport to the BAT/BIND port on my receiver.
Nathan's reply was no it wouldn't cause the receiver to go into bind mode.
He said the only way to get the receiver to go into bind mode is to jump between the negative and signal terminals.
Can your power expander cause a short/jump between the negative and signal terminals?
Thank you
Larry S | |
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