RPM measurement always show -1 value using hall sensor on DLE 30cc engine

ArduPlane
1

Hello everyone I need help to read RPM value on my pixhawk. Based on this page RPM Sensor Wiki - Knowledge Share I tried to read RPM but no success. My configuration are using tachometer signal provided by DLE 30cc CDI module and use voltage devider to change logic level from 5V to 3.3V. When I checked the voltage it showed that voltage will drop to 0V when the magnet close to the hall sensor which is good and I already tested it with arduino first to make sure nothing wrong with the sensor. Unfortunately the RPM value always showed -1. Here is my param

RPM_Max = 10000
RPM_Min = 10
PRM_Min_Qual = 0.5
RPM_Pin = 55 (Sensor plugged into Aux 6)
RPM_Scaling= 0.5
RPM_Type = 2
SERVO14_FUNCTION = -1 (Set AUX 6 as GPIO)

Can anyone help me show me what is wrong with my configuration ?

2

Before looking closely at your configuration what does this line in the messages screen say when you connect to Mission Planner?
RCout

3

thaks for your respond dave
I set SERVO13 and SERVO14 as GPIO because from the discussion it must be set to GPIO because its shared same timer. On pixhawk 6X it is AUX5 (GPIO 54) and AUX6 (GPIO 55)
image

And for update, I replaced voltage devider with 817 optocoupler module so the wiring look like this

LiPo 3S
LiPo 3S1920×1047 79.4 KB

I used 3.3V from cuav can pmu lite for reference because I’m not sure which pin from pixhawk 6x that I can use as 3.3V reference