https://devzone.nordicsemi.com/f/nordic-q-a/14249/gpio-wrongHi there! I have nRF51 DK (PCA10028). I config GIPO as below: nrf_drv_gpiote_out_config_t out_config = GPIOTE_CONFIG_OUT_SIMPLE(false); err_code = nrf_drv_gpiote_out_init(LED_1, &amp;out_config); APP_ERROR_CHECK(err_code); Why do LED_1 turnen-USTelligent Community 13Fri, 03 Jun 2016 01:27:14 GMThttps://devzone.nordicsemi.com/thread/54413?ContentTypeID=1Fri, 03 Jun 2016 01:27:14 GMT137ad170-7792-4731-bb38-c0d22fbe4515:46d7dabf-76f8-43c3-a91a-f42e311f1304Quinn<p>Thank you!</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/54412?ContentTypeID=1Thu, 02 Jun 2016 10:41:42 GMT137ad170-7792-4731-bb38-c0d22fbe4515:2280e598-3e3a-44f8-9ef3-991909922e94MartinBL<p>Hi,</p> <p><code>GPIOTE_CONFIG_OUT_SIMPLE(false);</code> will configure the pin with initial logic level low (or at 0 V if you want). The LEDs on the PCA10028 are connected like this:</p> <p><img src="https://devzone.nordicsemi.com/cfs-file/__key/communityserver-discussions-components-files/4/adfs.PNG" alt="image description" /></p> <p>so you can see that if the pin is low the LED will light up. If you want to initialize the LED to be off then simply write <code>GPIOTE_CONFIG_OUT_SIMPLE(true);</code>. It might seem a little backwards, but the true and false in the macro is with respect to high or low logic level, not whether or not the LEDs are on or off.</p><div style="clear:both;"></div>