Originally Posted by
cncmachineguy
something I've been thinking about. since this is music, i assume there is a predictable difference between the low or high numbers? I ask because if you could divide all the numbers to create a case type lookup.
The answer to 87.5 IMHO is to use 87 or 88. Since the half tests are hard coded in(at least for your example) no need to be exact.
The table I posted earlier was the shortened version, I had diffs formatting the full version, but this screenshot shows what I'm getting at...
(note the first two notes in the table will actually cause a timer 1 overflow and therefore can't be monitored when using a 20Mhz Osc - well not without extra code in the interrupt handler - so I include them only for completeness)
the frequency of the incoming signal is derived from the the number of comparator interrupts rx'ed for the frequency 'peroid' ...& becuase I want to map the frequency to a midi 'note' - and musical 'notes' are set in stone (ie no such thing a middle C.23) - I therefore also need to establish what the midway count is between successive note 'frequencies' (the note boundary if you like)
....but with a LUT 50 deep & with two conditions to check for per LUT entry, eg .....
Code:
if (comp1time>= 66194 and comp1time <= 62478) then note = $27
then if the incoming frequency is changing rapidly (becuase the notes are changing rapidly), then I need to have a fast way of resolving the incoming frequency to a note value.
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