Add firmware

firmware/base/src/stepper.h

@@ -0,0 +1,8 @@
+#pragma once
+#include "hardware/pio.h"
+
+void stepper_init();
+void start_pulse(PIO pio, uint sm, uint offset, uint pin, uint freq);
+
+void update_sm(PIO pio, uint sm, const uint pin, double v);
+void set_speeds(double vl, double vr);