== 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
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
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.