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RC Switch "Safe Start" feature is starting in "unsafe" 0v state, how to reverse it?


#1

Hi there,

I’m using the pololu RC switch to activate buttons on some machinery which would normally be activated by manually pushing the button. The button is a “push to make” switch which connects a normally 5v contact to ground in order to activate the machinery.

I have sucessfully configured the RC switches so that they are normally in the +5v state and will connect to ground when activated. This works perfectly to remotely “press” the buttons by radio control. Right up until I turned the system off and on again, then it all went very wrong.

Two big problems:

  1. If signal is lost then the RC switches default to the grounded state rather than the +5v state, which results in all the buttons being held down at once and some very undesirable resulting behaviour from the machinery!

  2. When the system is first switched on, the RC signals are requiring the RC switches to be at +5v (“on” for the RC switch, but “not pressed” for my buttons). Unfortunately this causes the RC switch to go into “safe start” mode (double flash). In safe start mode, the RC switches connect the outputs to ground, which results in all of the buttons being “pressed” at the same time. The absolute opposite of a safe start!

Is there any way to reverse the behaviour of the safe start so that +5v is the “safe” default instead of Grounding and/or so that it goes into “safe start” mode when the signal state is in the “off” range at startup instead of when it is in the “on” range at startup?

Thanks!
Chris


#2

Hello, Chris.

Which of our RC switches are you using? Do you have the product number? We have several that have different types of output.

-Nathan


#3

Thanks for the quick reply. They are “rc switch with digital output”. item #2801. 0J7740


#4

There is not a way to change the safe-start output state on that board. It sounds like our Pololu RC Switch with Small Low-Side MOSFET might be a better option for you. Instead of a digital output, those switches have a MOSFET on them that grounds the LOAD LOW pin when activated, so you could probably connect it in parallel with the button you mentioned.

By the way, we do not recommend using our products where failure might result in injury or property damage.

-Nathan