BLOG 12… Think we finally got it: PR12SAT

Over the last few months we have been working non-stop to improve the system reliability and eliminate the random resets and tracking failures.  I was down to the last common failure and spent a full week of trying to trap the failure.  After many hours of debugging it occurred to me that the failure was not a software bug at all but an electrical issue (I can get a little focused on an issue and go down the wrong path now and then).

This problem showed up at the end middle of a tracking operation; the system would reset and depending on the level of firmware tested it would have unpredictable results.  The issue turned out to be a power brown out in the CPU power system when both motors were stopped at the same time.    During the stopping process, reverse polarity is applied to the motors causing a large current draw due to the back EMF of the stopping motors in the motor power system.

Updates were added to the Motor Control Firmware such that the motors will not stop at the same time.  Along with the motor control firmware improvements a larger capacitor was added to help provide additional power reserves during the motor stop process.

Other new features have been added include a “Return to Home” menu choice and a small tone unit has been added to the Hand Controller to provide audio notification when the antenna has returned to home position or when an unexpected reset condition has occurred.  We have also more fully integrated the Magnetometer/Accelerometer hardware into the operations of the system and we are now including it as part of the PR12SAT base system.  See the updated User Manual revision 1.4 for further details.     73s – Will – N7IPY   10/06/16

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