It looks like the voltage is in the high byte and the high nibble of the low (second) byte.

The lower nibble of the low (second) byte is probably flags.

So simplifying my formula slightly and converting say 100V into the hex =

(100 x 126) - 1286 = 11314 = $2C32

Then AND $F0 to mask out the lower nibble or the low byte gives $2C30


The values in the formula look suspiciously like 127 or 128 am I missing something obvious with the conversion?

Is it really maths as shown on the voltage value to generate the hex?