Note that the timings are as measured, not required for correct opera…

…tion.

Any faster or more simple timing may be used.

Also update the timings as measured with the DS4014.

boot.inc

@@ -12,19 +12,21 @@
 ;
 ; All transmissions have a leader of 23 1-bits followed by 1 0-bit.
 ; Bit encoding starts at the least significant bit and is 8 bits wide.
-; 1-bits are encoded as 64.0us high, 72.8us low (135.8us total).
-; 0-bits are encoded as 27.8us high, 34.5us low, 34.4us high, 37.9 low
-; (134.6us total)
-; End of encoding adds 34.0us high, then return to input mode.
-; The last 0-bit low time is 32.6us instead of 37.9us, for some reason.
+; Measuring the Turnigy USB Linker results in the following timings:
+; 1-bits are encoded as 62.0us high, 72.0us low.
+; 0-bits are encoded as 27.7us high, 34.4us low, 34.4us high, 37.7 low.
+; Bit encoding takes about 134us in total.
+; End of encoding adds 34.4us high, then returns to input/pull-up mode.
 ;
-; We always learn the actual timing from the host's leader. It seems to
-; be possible to respond faster or slower, but faster will cause drops
-; between the host and its serial-to-USB conversion at 9600baud. It does
-; seem to work to use an average of high and low times as the actual bit
-; timing, but since it doesn't quite fit in one byte at clk/8 at 16MHz,
-; we store the high and low times separately, and copy the same timings.
-; We should still work even at many times the bit rate.
+; For this implementation, we always learn the actual timing from the
+; host's leader. The USB linker's implementation seems to accept faster
+; or slower responses, but faster will cause drops between the host and
+; its serial-to-USB conversion at 9600baud, so we always try to match or
+; be slower than the host's timing. It works to use an even fraction for
+; the actual bit timing, but since the total doesn't quite fit in a byte
+; at clk/8 at 16MHz, we store and use the high and low times separately.
+; This implementation should work with much faster pulses than currently
+; used by the USB linker.
 ;
 ; We support self-flashing ourselves (yo dawg), but doing so in a way
 ; that can still respond after each page update is a bit tricky. Some