zohsix
New Member
Posts: 8
Raspberry Pi: Yes
Other Device: Arduino
|
Post by zohsix on Mar 6, 2021 7:10:50 GMT -8
Hello, I am using the PI2Grover connected to a Grove Relay, set to Normally Open, to one of the digital connectors on the PI2Grover. As soon as I boot up, the relay is CLOSED (GPIO Pin is automatically set to HIGH by the boot process). The problem is that the relay powers a water pump and I don't want the pump running until the program tells it to run, not at boot up.
Is there anyway at boot up that I can set the GPIO output to LOW so that the pump won't run until a program sets the GPIO pin to HIGH? Regards, Dan
|
|
|
Post by SDL on Mar 7, 2021 13:31:25 GMT -8
No, by the very nature of the GPIO 3.3V tp 5.0V voltage translation, GPIO lines (which by definition are floating on power up - that can go either way) will wake up as a 1, until initialized and set to 0.
You could put a pulldown resistor to ground(a 1000 Ohm resistor) on the output and that would take it it 0, until it is driven high.
BP
|
|
zohsix
New Member
Posts: 8
Raspberry Pi: Yes
Other Device: Arduino
|
Post by zohsix on Mar 9, 2021 2:42:38 GMT -8
Thank you, I can try that. The relays I had available are the normally open variety. Could I replace those relays with a normally closed relay? Regards, Dan
|
|
|
Post by SDL on Mar 9, 2021 5:53:17 GMT -8
Changing to normally closed would work (If input = 1 keeps the relay open - check).
BP
|
|
zohsix
New Member
Posts: 8
Raspberry Pi: Yes
Other Device: Arduino
|
Post by zohsix on Mar 13, 2021 10:02:16 GMT -8
Changed the relay to a normally closed and it works perfectly. Regards, Dan
|
|