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| author | Lorenz Meier <lm@inf.ethz.ch> | 2013-12-27 12:02:57 +0100 |
|---|---|---|
| committer | Lorenz Meier <lm@inf.ethz.ch> | 2013-12-27 12:02:57 +0100 |
| commit | db46672bc4bfc4956baeb3f4d15d2fccf0ef3377 (patch) | |
| tree | 081d16bf0314a119bf9fe7fe1222d7e6a58436cd | |
| parent | affc8ae910a7c12bed266d9662822cee8afe1015 (diff) | |
| download | px4-firmware-db46672bc4bfc4956baeb3f4d15d2fccf0ef3377.tar.gz px4-firmware-db46672bc4bfc4956baeb3f4d15d2fccf0ef3377.tar.bz2 px4-firmware-db46672bc4bfc4956baeb3f4d15d2fccf0ef3377.zip | |
Paranoid PPM shape checking
| -rw-r--r-- | src/drivers/stm32/drv_hrt.c | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/src/drivers/stm32/drv_hrt.c b/src/drivers/stm32/drv_hrt.c index 5bfbe04b8..a6b005d27 100644 --- a/src/drivers/stm32/drv_hrt.c +++ b/src/drivers/stm32/drv_hrt.c @@ -1,6 +1,6 @@ /**************************************************************************** * - * Copyright (C) 2012 PX4 Development Team. All rights reserved. + * Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -336,17 +336,18 @@ static void hrt_call_invoke(void); /* * PPM decoder tuning parameters */ -# define PPM_MAX_PULSE_WIDTH 700 /* maximum width of a valid pulse */ +# define PPM_MIN_PULSE_WIDTH 200 /* minimum width of a valid first pulse */ +# define PPM_MAX_PULSE_WIDTH 600 /* maximum width of a valid first pulse */ # define PPM_MIN_CHANNEL_VALUE 800 /* shortest valid channel signal */ -# define PPM_MAX_CHANNEL_VALUE 2200 /* longest valid channel signal */ -# define PPM_MIN_START 2400 /* shortest valid start gap (only 2nd part of pulse) */ +# define PPM_MAX_CHANNEL_VALUE 2200 /* longest valid channel signal */ +# define PPM_MIN_START 2300 /* shortest valid start gap (only 2nd part of pulse) */ /* decoded PPM buffer */ #define PPM_MIN_CHANNELS 5 #define PPM_MAX_CHANNELS 20 /* Number of same-sized frames required to 'lock' */ -#define PPM_CHANNEL_LOCK 4 /* should be less than the input timeout */ +#define PPM_CHANNEL_LOCK 4 /* should be less than the input timeout */ __EXPORT uint16_t ppm_buffer[PPM_MAX_CHANNELS]; __EXPORT uint16_t ppm_frame_length = 0; @@ -518,8 +519,8 @@ hrt_ppm_decode(uint32_t status) case ARM: /* we expect a pulse giving us the first mark */ - if (width > PPM_MAX_PULSE_WIDTH) - goto error; /* pulse was too long */ + if (width < PPM_MIN_PULSE_WIDTH || width > PPM_MAX_PULSE_WIDTH) + goto error; /* pulse was too short or too long */ /* record the mark timing, expect an inactive edge */ ppm.last_mark = ppm.last_edge; @@ -533,8 +534,8 @@ hrt_ppm_decode(uint32_t status) case INACTIVE: /* we expect a short pulse */ - if (width > PPM_MAX_PULSE_WIDTH) - goto error; /* pulse was too long */ + if (width < PPM_MIN_PULSE_WIDTH || width > PPM_MAX_PULSE_WIDTH) + goto error; /* pulse was too short or too long */ /* this edge is not interesting, but now we are ready for the next mark */ ppm.phase = ACTIVE; |