helix serial.c: add some comment

This commit is contained in:
mtei 2018-10-29 02:23:48 +09:00 committed by Drashna Jaelre
parent 8517f8a660
commit d63fb6f716

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@ -1,5 +1,10 @@
/*
* WARNING: be careful changing this code, it is very timing dependent
*
* 2018-10-28 checked
* avr-gcc 4.9.2
* avr-gcc 5.4.0
* avr-gcc 7.3.0
*/
#ifndef F_CPU