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add calculation note for freq table

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gutmet 2022-10-26 11:19:39 +02:00
parent c46b5b198f
commit fba977510c
1 changed files with 17 additions and 0 deletions
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firmware/freq_table.md Normal file
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Frequency table
==============
calculation like:
```
rate = 8000000 / (3 * 64)
offset = 50
print "const uint16_t freq_table[] = {"
for i in range(100):
n = int(440.0 / rate * 2 ** ((i - offset) / 12.0) * 2 ** 16 + 0.5)
if n < 0x10000 / 2:
print "/*0x%02x*/\t%d," % (i, n)
print "};"
```