X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=blobdiff_plain;f=doc%2Fmotortest-installation.inc;h=290c7b8fa7d3542511944278321f2ae77c012bb6;hp=1edee68d4c57293bb32a12e53d854b623a9863c2;hb=HEAD;hpb=ef969428f293e5155c00af514ce0782a7cdf25d5

diff --git a/doc/motortest-installation.inc b/doc/motortest-installation.inc
index 1edee68d..778a914f 100644
--- a/doc/motortest-installation.inc
+++ b/doc/motortest-installation.inc
@@ -1,10 +1,27 @@
 == Installation
 
-	EasyMotor needs to be rigidly attached in the airframe, and the
-	long axis of the circuit board needs to be aligned with the axis
-	of flight. By default, the round beeper on the board should be
-	“up” towards the nose cone, and the screw terminal strips should
-	be “down” towards the fins and motor nozzle end of the rocket.
+	[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
 
@@ -40,6 +57,16 @@
 		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
@@ -51,4 +78,5 @@
 		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.
+		sensor ports that can be used with snap ring cases, 
+		and other related mechanical bits and pieces.