Add firmware code to repo (#8)

* Added primary stepper motor driver code to repo
* Added odometery encoder code to repo
* Added the ability to update encoder wheel ratio via ros service
Co-authored-by: Pimpest <82343504+Pimpest@users.noreply.github.com>
Co-committed-by: Pimpest <82343504+Pimpest@users.noreply.github.com>

firmware/base/src/quadrature.h

@@ -0,0 +1,27 @@
+#pragma once
+#include "hardware/pio.h"
+
+typedef struct substep_state_t {
+
+    uint calibration_data[4]; // relative phase sizes
+    uint clocks_per_us;       // save the clk_sys frequency in clocks per us
+    uint idle_stop_samples;   // after these samples without transitions, assume the encoder is stopped
+    PIO pio;
+    uint sm;
+
+    uint prev_trans_pos, prev_trans_us;
+    uint prev_step_us;
+    uint prev_low, prev_high;
+    uint idle_stop_sample_count;
+    int speed_2_20;
+    int stopped;
+
+    int speed;     
+    uint position; 
+
+    uint raw_step; 
+} substep_state_t;
+
+
+void substep_init_state(PIO pio, int sm, int pin_a, substep_state_t *state);
+void substep_update(substep_state_t *state);