https://devzone.nordicsemi.com/f/nordic-q-a/10339/pwm-inverted-when-not-using-seggerI&#39;m rolling my own very simple PWM implementation (I&#39;m not using the PWM example code). My code is below: #define GPIOTE_CHANNEL_NUMBER 0 #define PCLK16M 16000000 #define FSK_FREQ 17000 #define FSK_CC0 (PCLK16M / FSK_FREQ) #define FSK_PULSE_PERIOD_USen-USTelligent Community 13Thu, 19 Nov 2015 10:39:51 GMThttps://devzone.nordicsemi.com/thread/38381?ContentTypeID=1Thu, 19 Nov 2015 10:39:51 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6bd6cb02-3ffe-4926-a842-771ace5e2561Einar Thorsrud<p>It is not trivial to write software that reliably output a PWM on the nRF51. The <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk51.v10.0.0/lib_pwm.html?resultof=%22%70%77%6d%22%20%22%6c%69%62%72%61%72%79%22%20%22%6c%69%62%72%61%72%69%22%20">PWM library</a> in SDK 10 handles this properly, and I recommend you to use it. Earlier versions of the PWM library has problems with inversion.</p><div style="clear:both;"></div>