Signal conditionning and Filtering for use in close range
This range finder has a bad reading behavior (< 30cm) making the false signal jump to larger values (over 60cm)
Refer to image BENEWAKE_Dist_Strength_Filtered.jpg for more details.
BeneWake_TFMINI_CRC_Strength.ino
This program reads the binary message in this format Byte1-2 Byte3 Byte4 Byte5 Byte6 Byte7 Byte8 Byte9 0x59 59 Dist_L Dist_H Strength_L Strength_H Reserved Raw.Qual CheckSum_
Extract the Distance and Signal Strength values and apply some filtering in order to use use the ranges finder as a distance measurement unit for landing a quadcopter under ArduPilot
The values of: uint16_t strLimit = 1175; uint16_t distLow = 465; uint16_t offset = 90; Are determined experimentally by moving a reflective surface (colors cardboard) closer to sensor
uint16_t scale = 10; is adjusted according to sensor scaling == mm or cm output
Filtered serial output is sent @ 155200 baud to the flight controler and is consumed using the LightWare Serial driver. SERIAL4_PROTOCOL = 9 (Lidar) SERIAL4_BAUD = 115 RNGFND_TYPE = 8 (LightWareSerial) RNGFND_SCALING = 1 RNGFND_MIN_CM = 5 RNGFND_MAX_CM = 1200 RNGFND_GNDCLEAR = 15 //This is the minimal value set by the Arduino filter (240-90= 150mm = 15cm)