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+== 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.
projects / fw / altos / blobdiff