/* $Id$ */ /* * Copyright (c) 2011 Dimitri Sokolyuk * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include #include #include #include "kernel.h" #include "tasks.h" #define ON do { PORTB |= _BV(PB1); } while (0) #define OFF do { PORTB &= ~_BV(PB1); } while (0) #define ADCMAX (UINT16_MAX >> 6) /* 10 bit */ #define DL SEC4(1) #define DELIM SEC4(3) /* 0.3ms */ #define FRAME SEC2(2) /* 20ms */ #define SIGMIN SEC4(7) /* 0.7ms */ void ppm(void *arg) { struct ppmarg *a = (struct ppmarg *)arg; uint32_t t, n; uint8_t i; DDRB |= _BV(DDB1); ON; /* frame length 20ms, channel 0.7-1.7ms, stop 0.3 ms */ for (;;) { t = FRAME; for (i = 0; i < ADCCHANNELS; i++) { n = SIGMIN + SEC3(a->value[i]) / ADCMAX; t -= n + DELIM; /* channel frame 0.7..1.7ms high */ OFF; update(n, DL); /* start frame 0.3ms low */ ON; update(DELIM, DL); } /* sync frame */ OFF; update(t - DELIM, DL); ON; update(DELIM, DL); } }