doc: update EasyMotor behavior description for firmware 1.9.13 and later

diff --git a/doc/motortest-installation.inc b/doc/motortest-installation.inc
index 1edee68d4c57293bb32a12e53d854b623a9863c2..3914bc709b1ffbc0d136211601454f9b54547390 100644 (file)
--- 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