Several fixes.

MicroDexed.ino

@@ -718,7 +718,7 @@ void setup()
 #endif
 
   audio_timer.set_bpm(60);
-  audio_timer.function(4, &testfunc);
+  audio_timer.function(8, &testfunc); // 60 bpm with 1/8 pulses
 
 #ifdef DEBUG
   Serial.println(F("<setup end>"));

audio_timer.cpp

@@ -12,10 +12,10 @@ void AudioTimer::update(void)
 
   tick++;
 
-  if (tick >= float(beat)*float(bpm) + 0.5)
+  if (tick >= _steps)
   {
-    if (sequencer_step_function != NULL)
+    if (step_function != NULL)
-      (*sequencer_step_function)();
+      (*step_function)();
     tick = 0;
   }
 }
@@ -30,13 +30,14 @@ void AudioTimer::set_bpm(uint8_t b)
   bpm = b;
 }
 
-void AudioTimer::function(uint8_t steps, void(*func)())
+void AudioTimer::function(uint8_t stepping, void(*func)())
 {
+  steps = stepping;
   if (func != NULL)
   {
-    sequencer_step_function = func;
+    step_function = func;
-    steps = bpm * steps / 4;
+    _steps = beat * float(bpm) * 4.0 / float(stepping) + 0.5;
   }
   else
-    sequencer_step_function = NULL;
+    step_function = NULL;
 }

audio_timer.h

@@ -9,19 +9,21 @@ class AudioTimer : public AudioStream
     {
       tick = 0;
       bpm = 60;
-      sequencer_step_function = NULL;
+      steps = 4;
+      step_function = NULL;
     }
 
     virtual uint32_t get_tick(void);
     virtual void set_bpm(uint8_t b);
-    virtual void function(uint8_t steps, void(*func)());
+    virtual void function(uint8_t stepping, void(*func)());
     virtual void update(void);
 
   private:
     audio_block_t *inputQueueArray[1];
     uint8_t bpm;
-    uint16_t steps;
+    uint8_t steps;
-    void (*sequencer_step_function)();
+    uint16_t _steps;
+    void (*step_function)();
     volatile uint32_t tick;
     const float beat = AUDIO_SAMPLE_RATE_EXACT / float(AUDIO_BLOCK_SAMPLES) / 60.0;
 };