In_filter:
Dti = Adc_present - Adc_last ;test charging/discharging
Dti = Dti * 0.35             ; calibrate filter to secs
Dti = Dti / Fil_time         ; fil_time=cr time (adjustable)
Adc_last = Adc_last + Dti    ; form final output
Gosub Disp                   ; display it
Return