User avatar
Ace Rimmer
Posts: 104
Joined: Wed May 27, 2015 1:51 am
Location: Wit's End

Pi boots with LED on.

Fri Sep 30, 2016 3:42 am

I have an RGB led attached to pins GPIO pins 18,4 & 27 respectively on my B+. The led is used as an indicator at various times during program execution. When the program finishes all LEDs are off, however the next time the PI bootsup the green led (GPIO 4) is on although not as bright as normal :? Does GPIO 4 have some other use/purpose during bootup?
There must be an easier way!!!!!
I hope there is.....I haven't found it yet.

User avatar
rpdom
Posts: 15600
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Pi boots with LED on.

Fri Sep 30, 2016 4:33 am

GPIO 4 (pin 7) is used for the w1 (one-wire) bus, most commonly used for the DS18B20 temperature sensors. The driver will be polling the bus to look for devices every 10 seconds or so, and the rest of the time the pin will be used as input.

Check your /boot/config.txt for the w1-gpio dtoverlay line and comment it out to disable that driver.

User avatar
Ace Rimmer
Posts: 104
Joined: Wed May 27, 2015 1:51 am
Location: Wit's End

Re: Pi boots with LED on.

Fri Sep 30, 2016 6:04 am

Hi rpdom, you're up early this morning!
rpdom wrote:GPIO 4 (pin 7) is used for the w1 (one-wire) bus, most commonly used for the DS18B20 temperature sensors. The driver will be polling the bus to look for devices every 10 seconds or so, and the rest of the time the pin will be used as input.

Check your /boot/config.txt for the w1-gpio dtoverlay line and comment it out to disable that driver.
I thought to myself " this seems like an easy fix " so I did a quick nano /boot/config.txt but the only line that says anything about dtoverlay relates to i2c-rtc,ds3231. I suppose I could use another GPIO without too much worry but the connector is quite tidy the way I have it at the moment.
There must be an easier way!!!!!
I hope there is.....I haven't found it yet.

Return to “Troubleshooting”