[fw/altos] / doc / usage.inc

== 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]

                [WARNING]
                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.

        === Understanding Beeps

                Altus Metrum flight computers include a beeper to
                provide information about the state of the system.
                TeleMini doesn't have room for a beeper, so instead it
                uses an LED, which works the same, except for every
                beep is replaced with the flash of the LED.

                Here's a short summary of all of the modes and the beeping (or
                flashing, in the case of TeleMini v1) that accompanies each
                mode. In the description of the beeping pattern, “dit” means a
                short beep while "dah" means a long beep (three times as
                long). “Brap” means a long dissonant tone.

                .AltOS Modes
                [options="border",cols="1,1,2,2"]
                |====
                |Mode Name
                |Abbreviation
                |Beeps
                |Description

                |Startup
                |S
                |battery voltage in decivolts
                |Calibrating sensors, detecting orientation.

                |Idle
                |I
                |dit dit
                |Ready to accept commands over USB or radio link.

                |Pad
                |P
                |dit dah dah dit
                |Waiting for launch. Not listening for commands.

                |Boost
                |B
                |dah dit dit dit
                |Accelerating upwards.

                |Fast
                |F
                |dit dit dah dit
                |Decelerating, but moving faster than 200m/s.

                |Coast
                |C
                |dah dit dah dit
                |Decelerating, moving slower than 200m/s

                |Drogue
                |D
                |dah dit dit
                |Descending after apogee. Above main height.

                |Main
                |M
                |dah dah
                |Descending. Below main height.

                |Landed
                |L
                |dit dah dit dit
                |Stable altitude for at least ten seconds.


                |Sensor error
                |X
                |dah dit dit dah
                |Error detected during sensor calibration.
                |====

                Here's a summary of all of the Pad and Idle mode
                indications. In Idle mode, you'll hear one of these
                just once after the two short dits indicating idle
                mode. In Pad mode, after the dit dah dah dit
                indicating Pad mode, you'll hear these once every five
                seconds.

                .Pad/Idle Indications
                [options="header",cols="1,1,3"]
                |====
                |Name           |Beeps          |Description

                |Neither
                |brap
                |No continuity detected on either apogee or main igniters.

                |Apogee
                |dit
                |Continuity detected only on apogee igniter.

                |Main
                |dit dit
                |Continuity detected only on main igniter.


                |Both
                |dit dit dit
                |Continuity detected on both igniters.


                |Storage Full
                |warble
                |On-board data logging storage is full. This will
                 not prevent the flight computer from safely
                 controlling the flight or transmitting telemetry
                 signals, but no record of the flight will be
                 stored in on-board flash.
                |====

                For devices with a radio transmitter, in addition to
                the digital and APRS telemetry signals, you can also
                receive audio tones with a standard amateur
                70cm FM receiver. While on the pad, you will hear
                igniter status once every five seconds.

                .Pad Radio Indications
                [options="header",cols="1,1,3"]
                |====
                |Name           |Beeps          |Description

                |Neither
                |½ second tone
                |No continuity detected on either apogee or main igniters.

                |Apogee
                |dit
                |Continuity detected only on apogee igniter.

                |Main
                |dit dit
                |Continuity detected only on main igniter.


                |Both
                |dit dit dit
                |Continuity detected on both igniters.

                |====

                During ascent, the tones will be muted to allow the
                telemetry data to consume the full radio bandwidth.

                During descent and after landing, a ½ second tone will
                be transmitted every five seconds. This can be used to
                find the rocket using RDF techniques when the signal
                is too weak to receive GPS information via telemetry
                or APRS.

        === Turning On the Power

                Connect a battery and power switch and turn the switch
                to "on". The flight computer will signal power on by
                reporting the battery voltage and then perform an internal self
                test and sensor calibration.

                Once the self test and calibration are complete, there
                are two modes that an Altus Metrum flight computer can
                operate in:

                Flight/Pad::
                The flight computer is waiting to detect
                launch and then fly the rocket. In this mode, the USB
                link is disabled, and the radio goes into
                transmit-only mode. The only way to get out of this
                mode is to power the flight computer down.

                Idle::
                The flight computer is ready to communicate over USB
                and in packet mode over the radio. You can configure
                the flight computer, download data or display
                the current state.

                For flight computers with accelerometers (TeleMetrum,
                EasyMega and TeleMega), the mode is selected by the
                orientation of the board during the self test
                interval. If the board is pointing upwards as if ready
                to fly, it will enter Flight/Pad mode. Otherwise, it will
                enter Idle mode.

                For EasyMini, if the USB cable is connected to a
                computer, it will enter Idle mode. Otherwise, it will
                enter Flight/Pad mode.

                For TeleMini v1.0, if a packet link is waiting to
                connect when the device is powered on, it will enter
                Idle mode, otherwise it will enter Flight/Pad mode.

                You can see in <<_understanding_beeps>>
                how to tell which mode the flight computer is in.

        === 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 <<_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 for each flight computer will be found
                in the section below for that flight computer.

        === 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.

                [WARNING]
                TeleMega, EasyMega and TeleMetrum are only designed to
                operate off a single-cell Lithium Polymer battery and
                cannot be used with any other kind. Connecting a
                different kind of battery to any of these will destroy
                the board.