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Minor clarifications

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Timur Iskhodzhanov 2021-07-24 21:17:10 -07:00
parent 0e4720cb36
commit 934b18ef1b
1 changed files with 4 additions and 6 deletions
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can_db/mazda_mx5_nd.md
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@ -25,17 +25,15 @@ The binary representation used for the brake pedal/pressure is very weird.
In my limited testing, I've observed the values of 149...154 when not touching
the brake pedal. Most of the time it stays as 154. When progressively pressing
the brake pedal, the number goes up to 255, then wraps around to 0, and keeps
going up. I've observed values as high as 145 when heavy braking.
It feels very much like
going up. I've observed values as high as 145 when heavy braking, and ~135 when
braking hard enough to engage ABS. It very much feels like the representation is
`(cast_to_int(brake_pressure * multiplier) + offset) % 255`, as long as we allow
the `brake_pressure` to go slightly negative, and as long as the binary
representation for the maximum possible value and the binary representation for
the minimal possible values don't conflict with each other.
the `brake_pressure` to go slightly negative.
Now out of all 0...255 possible values, this leaves us with only 146...148
values that I haven't observed. For now, I've made an assumption that 146 is
"braking even harder than I was ever able to brake", and 147 and 148 are just
values "even more negative than I was able to observe". It is recommended to log
values "even more vacuum than I was able to observe". It is recommended to log
the `E` byte by itself in a separate channel (e.g. "Digital 1") for diagnostic
purposes so that if you ever see the "brake position" jump from 0% to 100% when
you're not braking, or from 100% to 0% when you're braking super hard, we can