examples: Add CV select sample (#9)

* Add files via upload

* Update CV_select.py

* firmware: Add select_from_list_using_cv helper

* examples: Add CV select example

Co-authored-by: Thea Flowers <me@thea.codes>

Author: odeliy

examples/cv_select.py

@@ -0,0 +1,37 @@
+# This example determines which sample to play based on the
+# pitch CV input- useful for things like drum samples.
+
+import winterbloom_bhb
+
+bhb = winterbloom_bhb.BigHonkingButton()
+
+samples = [
+    bhb.load_sample("samples/clap.wav"),
+    bhb.load_sample("samples/dist.wav"),
+    bhb.load_sample("samples/go.wav"),
+    bhb.load_sample("samples/honk.wav"),
+    bhb.load_sample("samples/kick.wav"),
+    bhb.load_sample("samples/reverse.wav"),
+    bhb.load_sample("samples/snare.wav"),
+]
+
+while True:
+    if bhb.triggered:
+        # This selects a sample from the list based on the pitch CV input.
+        # The samples are evenly distributed across the CV range,
+        # -5v to +5v. So if you send -5v it'll select the first sample and
+        # if you send +5v it'll select the last one, with voltages in-between
+        # will select the closest sample in the list.
+        sample = bhb.select_from_list_using_cv(samples, bhb.pitch_in)
+
+        # By default, this uses the full CV range but you can change it by
+        # specifying low and high - useful if you only have a positive CV
+        # source.
+
+        # sample = bhb.select_from_list_using_cv(samples, bhb.pitch_in, low=0, high=5)
+
+        bhb.play(sample)
+        bhb.gate_out = True
+
+    if bhb.released:
+        bhb.gate_out = False

firmware/winterbloom_bhb/bhb.py

@@ -71,10 +71,14 @@ def __init__(self):
             self._pitch_in.direct_calibration(
                 {4068: -5.0, 3049: -2.5, 2025: 0, 1001: 2.5, 8: 5.0}
             )
+            self.min_cv = -5.0
+            self.max_cv = 5.0
         else:
             self._pitch_in.direct_calibration(
                 {4068: -2.0, 3049: -1.0, 2025: 0, 1001: 1.0, 8: 2.0}
             )
+            self.min_cv = -2.0
+            self.max_cv = 2.0
 
         self.audio_out = audioio.AudioOut(board.HONK_OUT)
 
@@ -141,3 +145,16 @@ def play(self, sample, pitch_cv=None, loop=False):
 
     def stop(self):
         self.audio_out.stop()
+
+    def select_from_list_using_cv(self, list, cv, low=None, high=None):
+        if low is None:
+            low = self.min_cv
+        if high is None:
+            high = self.max_cv
+
+        cv = min(high, max(low, cv))
+        count = len(list)
+        span = high - low
+        value = cv - low
+        index = int((value / span) * count)
+        return list[index]

user_guide/docs/index.md

@@ -101,6 +101,7 @@ Big Honking Button can do all sorts of things! We've made a few examples to get
 
 1. [Cycle example](https://github.com/wntrblm/Big_Honking_Button/blob/main/examples/cycle.py): Shows how to load multiple samples and cycle between them.
 1. [Random example](https://github.com/wntrblm/Big_Honking_Button/blob/main/examples/random.py): Shows how to load multiple samples and choose one at random.
+1. [CV select example](https://github.com/wntrblm/Big_Honking_Button/blob/main/examples/cv_select.py): Shows how to load multiple samples and use the CV input to select which one to play.
 1. [Tap tempo example](https://github.com/wntrblm/Big_Honking_Button/blob/main/examples/tap_tempo.py): Shows how to use the button to set the tempo and have the module play back a sample at each beat.
 1. [Sine example](https://github.com/wntrblm/Big_Honking_Button/blob/main/examples/sine.py): An advanced example that shows how to generate a custom waveform.
 1. [Noise example](https://github.com/wntrblm/Big_Honking_Button/blob/main/examples/noise.py): An advanced example that shows how to generate noise.