Use arduino insteand of jumper shunt cap

[arpa123]

i have a module that controll a bldc motor, and to controll direction of motor i need to move the jumper shunt cap manually

so i have 3 wires and if i connect 1st with 2nd with cap motor rotate forward ,

if i cap connect 2nd with 3rd motor rotate backward

gnd is connected together with arduino and if i check those 3 wires with multimeter i read voltage like this (check image)

i think middle wire is the wire that control the motor rotation direction.

because if i manyally connect to gnd or 5v then motor change direction.

i tried connectind to arduino pin 3 and use digitalWrite(HIGH) and digitalWrite(LOW) but im not able to make motor rotate forward so i think i cant give a real GND to it

[xfpd]

Use an arduino-compatible relay to close/open/change the connections (jumpers). Control the relay with the Arduino.

[arpa123]

is npn transistor ok for this or must use relay

[Paul_KD7HB]

@arpa123

because if i manyally connect to gnd or 5v then motor change direction.

A transistor is only OFF and ON. How would an off and on switch be able to move your wires. A single relay can repeat just what you did.

[arpa123]

coz if i dont add gnd its 5v (i think it is like pullup resistor) if i dont connect anything wire is 5v and motor go in one direction if i connect GND then it switch to other direction,

so if there is a way to send GND on it i think it can do the job

[arpa123]

i tried connecting bd679 NPN transistor ,

arduino pin to Base,
collector to GND
emiter to the module wire

now its always act like connecting GND to the module wire wether or not i make arduino pin HIGH or LOW , maybe need any resistor ?

i measure GND and emitter when transistor is on/off and i get 8.2Kohm and 270 Kohm

[xfpd]

[Smajdalf]

Show your code. Maybe you did not make the pin OUTPUT?
Measure voltage on the Arduino pin when disconnected from the driver. Does it go HIGH and LOW as expected? This is probably a logic input, you should have no trouble to drive it directly from Arduino.