Initial Commit - Copy from Altus Metrum AltOS

doc/motortest-installation.inc

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+== Installation
+
+	[WARNING]
+	Firmware versions prior to 1.9.13 used acceleration to detect
+	launch.  Starting with 1.9.13, the firmware switched to using
+	pressure to trigger recording. Altus Metrum strongly recommends 
+	upgrading all EasyMotor boards to current firmware, the
+	behavior of which is described here.
+
+	EasyMotor needs to be rigidly attached in the airframe, in any
+	convenient orientation.
+
+	=== Trigger to Start Recording
+
+	Starting with firmware version 1.9.13, a pressure sensor must
+	be attached, and pressure change is used to initiate and conclude
+	data recording.  Pressure and 3 axes of acceleration are recorded
+	for later analysis.
+
+	EasyMotor looks for a 50 psi rise in pressure from ambient to
+	start recording.  Recording stops when the pressure drops 
+	below 50 psi and shows variation of less than 30 psi for at 
+	least 10 seconds. These conditions are intended to capture all
+	actual burn data including anomalies such as "chuffs".
+
+	=== Power Switch and Battery
+
+		In addition to the circuit board itself, EasyMotor needs
+		a power switch and battery to operate.  Like many Altus 
+		Metrum products, EasyMotor requires a single-cell LiPo 
+		battery, and has an on-board charging circuit.  The 5V
+		needed for inexpensive pressure sensors is generated 
+		onboard using a switching regulator to boost the voltage.
+
+		Because he often mounts EasyMotor to the motor's forward
+		bulkhead instead of to the airframe itself, Bdale often
+		uses a length of “shooter wire” from an e-match or used
+		motor igniter as a power switch, routing the wire out of
+		the typical fin can vent hole and using “twist and tape”
+		to power up the board. Whatever works!
+
+	=== Pressure Sensor
+
+		The primary motivation for designing EasyMotor was to have
+		a reliable way of recording motor chamber pressure during
+		flight. To that end, EasyMotor supports attachment of a
+		low-cost analog pressure sensor. The board provides 5V
+		to power the sensor, and an input for measuring and
+		logging the output voltage from the sensor.
+
+		The kind of sensor EasyMotor is designed to work with
+		takes 5V in and has a linear analog output that ranges
+		from 0.5V at 0 to 4.5V at the maximum pressure supported
+		by the sensor. Very inexpensive sensors that have a
+		“1/8 NPT” threaded input, a “Buick-style” 3-pin connector,
+		and typically ship with a short cable and mating
+		connector, are readily available through various vendors
+		including Amazon, eBay, and AliExpress.
+
+		These pressure sensors have three wires and sometimes a 
+		shield around those wires.  The colors of the wires can vary, 
+		but typically are red for power, black for ground, and green 
+		for the analog output.  Hook red to '+5', green to 'PRES', and
+		black to one of the two 'GND' screws on the board.  The other
+		'GND' screw is available for connecting the shield if one is
+		present.  This is mostly relevant if you're using the product
+		for static testing on the ground with a longer than usual
+		cable. 
+
+		To log in-flight chamber pressure, a typical approach
+		might be to drill a 1/8" sampling hole all the way
+		through the center of the motor's forward closure, then
+		drill and tap partially through the closure with a “1/8
+		NPT” pipe tap. Fill the touch hole with grease, screw in
+		the pressure sensor, and attach the sensor leads to
+		EasyMotor.
+
+		If you aren't up for machining closures yourself, 
+		link:http://lokiresearch.com[Loki Research] sells 
+		54mm and 75mm "experimental bulkheads" with threaded
+		sensor ports that can be used with snap ring cases, 
+		and other related mechanical bits and pieces.