Diagnoses and Cures

Hermione’s “reach for the stars” was due to I²C errors; I suspected powewr brown-outs.  Her regulator for the LiPo provided only 1.5A, so I tried her passively with mains PSU of 5V at 1A and 2.5A – the error was the same – shifted outputs from the IMU FIFO without any FIFO overflow.  That suggested a interaction with the I²C with the Garmin instead.  I rebuilt the cable with two UTPs (unshielded twisted pairs): SCL with Vss / GND and SDA with Vdd / 5V as per the PX4FLOW spec for long I²C wiring.  I was stunned – it just worked, regardless of whether the 1A or 2.5A power supply was used, I no longer got any I²C corruption.  Next step clearly is to test her live outdoors and check she no longer reaches for the stars.

I also had the bottle to let Zoe loose in the play room.  She still hardly got off the ground on the first flight, so it’s not temperature drift.  However, her second run was perfect, which reminded me that her first run was always cr@p for some reason.  Here’s the stats for both.  The stats are logging both accelerometer and Garmin / Camera distances.  There’s such a tight correlation between the very difference sensors that I’m very tempted to turn the fusion on.  Just a tad more bottle needed.  The key one for each is the bottom left: how high was she according to the two sensor sources.

Flight one

Flight one

Flight 2

Flight 2

I thinkthat’s my courage bottle empty for the day.  When it’s charged up tomorrow, I’ll take the sisters outside to test the above next steps.

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