Cycle CS pin in case of checksum error #4
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marius-meissner
requested changes
Aug 14, 2023
| @@ -942,6 +942,7 @@ where | |||
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| let pec = PEC15::calc(&result[0..6]); | |||
| if pec[0] != result[6] || pec[1] != result[7] { | |||
| self.cs.set_high().map_err(Error::CSPinError)?; | |||
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From my point of view, it's the correct & expected behavior for setting the CS pine state here.
As the only upper method calling read() is within read_daisy_chain(), which is managing the CS pin state (except the case you just found).
| @@ -973,13 +974,13 @@ where | |||
| } | |||
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| // Constant of 276 °C, which needs to be subtracted | |||
| const TEMP_SUB: i16 = 20976; | |||
| const TEMP_SUB: i32 = 20976; | |||
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Nice catch!
Please try to add a unit test.
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With this PR, I’m adding a line which disables the CS pin in case of a checksum error.
Sometimes it happens that a slave gets in a state which never exits a loop of checksum errors, and a chip select cycle is needed.
With this fix, my firmware never gets stuck in that kind of loop. I don’t know whether this solution applies universally, so I’d like to have my change reviewed, as I am still relatively new to this BMS chip (LTC6813).
I also don’t know if state changes of the CS pin should happen in this function, as callers might not expect this.