diff --git a/extras/pwm/pwm.c b/extras/pwm/pwm.c
index 35f0f71..371518e 100644
--- a/extras/pwm/pwm.c
+++ b/extras/pwm/pwm.c
@@ -127,6 +127,7 @@ void pwm_set_freq(uint16_t freq)
         pwmInfo._maxLoad = timer_get_load(FRC1);
         pwmInfo.freq = freq;
         debug("Frequency set at %u",pwmInfo.freq);
+        debug("MaxLoad is %u",pwmInfo._maxLoad);
     }
 
     if (pwmInfo.running)
@@ -161,6 +162,13 @@ void pwm_start()
     pwmInfo._offLoad = pwmInfo._maxLoad - pwmInfo._onLoad;
     pwmInfo._step = PERIOD_ON;
 
+    if(!pwmInfo._onLoad)
+    {
+        debug("Can't set timer with low duty and frequency settings, put duty at 0");
+        pwmInfo.dutyCycle = 0;
+    }
+
+    // 0% and 100% duty cycle are special cases: constant output.
     if (pwmInfo.dutyCycle > 0 && pwmInfo.dutyCycle < UINT16_MAX)
     {
         // Trigger ON
diff --git a/extras/pwm/pwm.h b/extras/pwm/pwm.h
index f00d740..2efb100 100644
--- a/extras/pwm/pwm.h
+++ b/extras/pwm/pwm.h
@@ -16,6 +16,8 @@
 extern "C" {
 #endif
 
+//Warning: Printf disturb pwm, use uart_putc instead.
+
 void pwm_init(uint8_t npins, const uint8_t* pins, uint8_t reverse);
 void pwm_set_freq(uint16_t freq);
 void pwm_set_duty(uint16_t duty);