First off, my name is Ha and this is my very first post in this forum. I am very new to Arduino yet have basic knowledge about microcontroller, resister, caps and those kind of simple electronic components.
MY PROJECT I am making a simple gear position indicator for my car. my car has OBD1 connector and has a terminal named TT, when the car runs voltage between TT and E1 (Earth) varies when the tranny shifts. the below table is from repair manual
the tasks looks simple: keep measuring voltage between TT and E1 and indicate related gear position to a 7 segment led.
TEST LAB I built a bench test on breadboard with voltage devider on Arduino Leonardo, it simply reads analog voltage from pin A0 and it works fine showing correct calculated voltage of a 9v battery to serial output.
I then connect a pot to the circuit, when I adjust pot resistance, serial output show voltage gradually up and down nicely.
PROBLEM But when I connect the test board to pin TT & E1 on car and run it. serial output showed only 2 value 0 or sparks of 6volt (approx.) every now and then INSTEAD OF a series of voltage gradually increase from 0 to 6.xx as it was when I used a multimeter in place of the Andruino board.
I dont know where to start at to fight the problem. please share your ideas