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| author | Lorenz Meier <lm@inf.ethz.ch> | 2014-02-21 12:27:04 +0100 |
|---|---|---|
| committer | Lorenz Meier <lm@inf.ethz.ch> | 2014-02-21 12:27:04 +0100 |
| commit | 06b69b70a5d73ba32bc08cacedbeb9016a32195b (patch) | |
| tree | 2a815b2f742dfb6f6881d2f156168773c41630fa /src/modules/px4iofirmware | |
| parent | 57216ac6feac740d1a65dbbfc7611adced5f774a (diff) | |
| download | px4-firmware-06b69b70a5d73ba32bc08cacedbeb9016a32195b.tar.gz px4-firmware-06b69b70a5d73ba32bc08cacedbeb9016a32195b.tar.bz2 px4-firmware-06b69b70a5d73ba32bc08cacedbeb9016a32195b.zip | |
Scaling Spektrum inputs into normalized value same as the servo outputs do
Diffstat (limited to 'src/modules/px4iofirmware')
| -rw-r--r-- | src/modules/px4iofirmware/dsm.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/src/modules/px4iofirmware/dsm.c b/src/modules/px4iofirmware/dsm.c index 0d3eb2606..aac2087b2 100644 --- a/src/modules/px4iofirmware/dsm.c +++ b/src/modules/px4iofirmware/dsm.c @@ -369,11 +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 = (((value - 1024) * 1000) / 1700) + 1500; /* * Store the decoded channel into the R/C input buffer, taking into |