diff options
Diffstat (limited to 'src/modules/px4iofirmware/dsm.c')
| -rw-r--r-- | src/modules/px4iofirmware/dsm.c | 34 |
1 files changed, 29 insertions, 5 deletions
diff --git a/src/modules/px4iofirmware/dsm.c b/src/modules/px4iofirmware/dsm.c index 60eda2319..d3f365822 100644 --- a/src/modules/px4iofirmware/dsm.c +++ b/src/modules/px4iofirmware/dsm.c @@ -1,6 +1,6 @@ /**************************************************************************** * - * Copyright (C) 2012 PX4 Development Team. All rights reserved. + * Copyright (c) 2012-2014 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 @@ -162,6 +162,7 @@ dsm_guess_format(bool reset) 0xff, /* 8 channels (DX8) */ 0x1ff, /* 9 channels (DX9, etc.) */ 0x3ff, /* 10 channels (DX10) */ + 0x1fff, /* 13 channels (DX10t) */ 0x3fff /* 18 channels (DX10) */ }; unsigned votes10 = 0; @@ -368,11 +369,25 @@ dsm_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values) if (channel >= *num_values) *num_values = channel + 1; - /* convert 0-1024 / 0-2048 values to 1000-2000 ppm encoding in a very sloppy fashion */ - if (dsm_channel_shift == 11) - value /= 2; + /* convert 0-1024 / 0-2048 values to 1000-2000 ppm encoding. */ + if (dsm_channel_shift == 10) + value *= 2; - value += 998; + /* + * Spektrum scaling is special. There are these basic considerations + * + * * Midpoint is 1520 us + * * 100% travel channels are +- 400 us + * + * We obey the original Spektrum scaling (so a default setup will scale from + * 1100 - 1900 us), but we do not obey the weird 1520 us center point + * and instead (correctly) center the center around 1500 us. This is in order + * to get something useful without requiring the user to calibrate on a digital + * link for no reason. + */ + + /* scaled integer for decent accuracy while staying efficient */ + value = ((((int)value - 1024) * 1000) / 1700) + 1500; /* * Store the decoded channel into the R/C input buffer, taking into @@ -400,6 +415,15 @@ dsm_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values) values[channel] = value; } + /* + * Spektrum likes to send junk in higher channel numbers to fill + * their packets. We don't know about a 13 channel model in their TX + * lines, so if we get a channel count of 13, we'll return 12 (the last + * data index that is stable). + */ + if (*num_values == 13) + *num_values = 12; + if (dsm_channel_shift == 11) { /* Set the 11-bit data indicator */ *num_values |= 0x8000; |