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Launch and Remove Before Flight Switches

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Launch and Remove Before Flight Switches

Postby applewood » Mon Jun 09, 2008 2:06 am

I was wondering if you could provide a little more information on exactly how the Launch and RBF switches work on the Dev Board as well as the CubeSat.

Specifically, does the Launch Switch interrupt the flow of power to the FM430 allowing it to connect when triggered, or does it simply change a bit the 430 can read, or something else?

I appreciate any more info on this.

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Re: Launch and Remove Before Flight Switches

Postby aek » Mon Jun 09, 2008 2:40 am

The Launch and RBF switches are simply high-current paths that can be connected to pins dedicated pins S[5..0] on the CubeSat Kit Bus.

You can use them anyway you want. Clyde Space uses them in the CubeSat Kit EPS in one of the ways I intended: http://www.clyde-space.com/1U%20CubeSat%20Power%20Datasheet.pdf (they call the RBF and Launch Switches the Pull-Pin and Separation switches).

These switches are generally used to make or break power circuits. Usually, they are employed in a manner that is CubeSat-Kit wide -- e.g. in the CS EPS example, pulling the RBF pin connects the battery negative contact to ground, thus completing the battery circuit(s). Once the Separation / Launch switch closes, power can flow in the CS EPS from the batteries to the output regulators and onto the CSK Bus.

Note that the CS EPS uses only four of the six available switch terminals. You can use the remaining two in novel ways, e.g. as an I/O pin to the MSP430 on the FM430 to sense a certain switch condition. You'd do that by connecting the corresponding Sx pin to an I/O pin on the CSK bus connector through an interface circuit.


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