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diff --git a/doc/usage.inc b/doc/usage.inc new file mode 100644 index 00000000..b4a93271 --- /dev/null +++ b/doc/usage.inc @@ -0,0 +1,90 @@ +== Using Altus Metrum Hardware + + Here are general instructions for hooking up an Altus Metrum + flight computer. Instructions specific to each model will be + found in the section devoted to that model below. + + === Wiring and Electrical Interference + + To prevent electrical interference from affecting the + operation of the flight computer, it's important to always + twist pairs of wires connected to the board. Twist the switch + leads, the pyro leads and the battery leads. This reduces + interference through a mechanism called common mode rejection. + + === Hooking Up Lithium Polymer Batteries + + All Altus Metrum flight computers have a two pin JST PH + series connector to connect up a single-cell Lithium Polymer + cell (3.7V nominal). You can purchase matching batteries + from the Altus Metrum store, or other vendors, or you can + make your own. Pin 1 of the connector is positive, pin 2 is + negative. Spark Fun sells a cable with the connector + attached, which they call a + link:https://www.sparkfun.com/products/9914[JST Jumper 2 Wire Assembly] + + Many RC vendors also sell lithium polymer batteries with + this same connector. All that we have found use the opposite + polarity, and if you use them that way, you will damage or + destroy the flight computer. + + === Hooking Up Pyro Charges + + Altus Metrum flight computers always have two screws for + each pyro charge. This means you shouldn't need to put two + wires into a screw terminal or connect leads from pyro + charges together externally. + + On the flight computer, one lead from each charge is hooked + to the positive battery terminal through the power switch. + The other lead is connected through the pyro circuit, which + is connected to the negative battery terminal when the pyro + circuit is fired. + + === Hooking Up a Power Switch + + Altus Metrum flight computers need an external power switch + to turn them on. This disconnects both the computer and the + pyro charges from the battery, preventing the charges from + firing when in the Off position. The switch is in-line with + the positive battery terminal. + + === Using an External Active Switch Circuit + + You can use an active switch circuit, such as the + Featherweight Magnetic Switch, with any Altus Metrum + flight computer. These require three connections, one to + the battery, one to the positive power input on the flight + computer and one to ground. Find instructions on how to + hook these up for each flight computer below. The follow + the instructions that come with your active switch to + connect it up. + + === Using a Separate Pyro Battery + + As mentioned above in the section on hooking up pyro + charges, one lead for each of the pyro charges is connected + through the power switch directly to the positive battery + terminal. The other lead is connected to the pyro circuit, + which connects it to the negative battery terminal when the + pyro circuit is fired. The pyro circuit on all of the flight + computers is designed to handle up to 16V. + + To use a separate pyro battery, connect the negative pyro + battery terminal to the flight computer ground terminal, + the positive battery terminal to the igniter and the other + igniter lead to the negative pyro terminal on the flight + computer. When the pyro channel fires, it will complete the + circuit between the negative pyro terminal and the ground + terminal, firing the igniter. Specific instructions on how + to hook this up will be found in each section below. + + === Using a Different Kind of Battery + + EasyMini and TeleMini v2 are designed to use either a + lithium polymer battery or any other battery producing + between 4 and 12 volts, such as a rectangular 9V + battery. TeleMega, EasyMega and TeleMetrum are not designed for this, + and must only be powered by a lithium polymer battery. Find + instructions on how to use other batteries in the EasyMini + and TeleMini sections below. |