AP_EFI: Hirth: fix sensor health flags

[robertlong13]

There is no crankshaft sensor status reported by this EFI. This line is misleading and should be removed. The sensor health bitmask is already logged elsewhere.

[peterbarker]

How did we end up with this in here, then?

Is it in the datasheet?

[robertlong13]

How did we end up with this in here, then?

I really don't know how this got there. I asked around but didn't get a confident answer.

Is it in the datasheet?

No, that sensor_ok bitmask holds 4 bits for 4 different sensor healths, none of which are crankshaft, and all 4 of which are logged a couple lines later correctly. From the bitwise & here, you'd think that CRANK_SHAFT_SENSOR_OK held a single bit, but it doesn't: its 0x0F (4 LSB set). So this line is effectively marking crankshaft sensor healthy if any of these 4 sensors are healthy, and unhealthy if all are unhealthy.

[robertlong13]

While I was here, I noticed that our other sensor health bitmask is actually wrong. The datasheet shows bits 1-4, not bits 0-3, and I have confirmed with my Hirth EFI that bit 0 always reports 0.

I have pushed another commit to this PR to address that too.

[peterbarker]

Merged, thanks!