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Scaling Spektrum inputs into normalized value same as the servo outputs do

This commit is contained in:
Lorenz Meier 2014-02-21 12:27:04 +01:00
parent 57216ac6fe
commit 06b69b70a5
1 changed files with 18 additions and 4 deletions
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22
src/modules/px4iofirmware/dsm.c
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@ -369,11 +369,25 @@ dsm_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values)
if (channel >= *num_values) if (channel >= *num_values)
*num_values = channel + 1; *num_values = channel + 1;
/* convert 0-1024 / 0-2048 values to 1000-2000 ppm encoding in a very sloppy fashion */ /* convert 0-1024 / 0-2048 values to 1000-2000 ppm encoding. */
if (dsm_channel_shift == 11) if (dsm_channel_shift == 10)
value /= 2; 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 * Store the decoded channel into the R/C input buffer, taking into