check routine in C++ and python

native/native.C

@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <math.h>
+
+static const double nr_teeth_small = 11.0;
+static const double nr_teeth_big = 53.0;
+static const double axis_hinge_dist_mm = 200;
+
+#define PI M_PI
+
+static const double earth_rot_speed_rad_sec = 2*PI / (1440*60*1000);
+static const double bolt_thread_mm = 1.25;
+
+
+/* static const unsigned int microstepping_div = 16; */
+/* static const unsigned int nr_steps = 200 * microstepping_div; */
+
+/* static const double stepper_gear_rad_per_step = (2*PI) / nr_steps; */
+
+
+// this needs to be reset
+/* static struct rot_state_t { */
+/*   unsigned long elapsed_time_millis; */
+/*   double stepper_gear_rot_rad = 0; */
+/* } rot_state; */
+
+
+static double get_expected_stepper_rot(unsigned long elapsed_time_millis) {
+  const double r = tan(fmod(earth_rot_speed_rad_sec * (elapsed_time_millis), PI)) * axis_hinge_dist_mm * 2 * PI * nr_teeth_big / (bolt_thread_mm * nr_teeth_small);
+
+  return r;
+}
+
+
+int main(int argc, char **argv) {
+  unsigned long millis_step = 0;
+
+  for (millis_step=0; millis_step < 1000; millis_step++) {
+    printf("%d (%d sec) : %f\n", millis_step*1000, millis_step, get_expected_stepper_rot(millis_step * 1000));
+
+  }
+  return 0;
+}

native/native.py

@@ -0,0 +1,46 @@
+#!/usr/bin/env python3
+
+import sys
+import numpy
+
+BOLT_THREAD = 1.25
+NR_TEETH_BIG=53
+NR_TEETH_SMALL=11
+
+EARTH_SIDERAL_DAY = 1440
+HINGE_ROD_LEN = 200
+
+def rodlen_to_angle(rod_len):
+    return numpy.arctan(rod_len / HINGE_ROD_LEN)
+
+def drivegear_angle_to_rodlen(angle):
+    return BOLT_THREAD*angle/(2*numpy.pi)
+
+def steppergear_angle_to_drivegear_angle(sangle):
+    return sangle * NR_TEETH_SMALL/NR_TEETH_BIG
+
+
+def debug_from_step_angle(sangle):
+    step_angle = float(sangle)
+
+    print("Step angle {}rad".format(step_angle))
+
+    drivegear_angle = steppergear_angle_to_drivegear_angle(step_angle)
+
+    print("Drive gear angle {}rad".format(drivegear_angle))
+
+    rodlen = drivegear_angle_to_rodlen(drivegear_angle)
+
+    print("Rod length {}mm".format(rodlen))
+
+    final_angle = rodlen_to_angle(rodlen)
+
+    print("Final angle {}rad".format(final_angle))
+
+def get_step_angle_from_time(time_in_sec):
+    final_angle = time_in_sec *  2 * numpy.pi / (1440*60)
+    sangle = numpy.tan(final_angle) * HINGE_ROD_LEN * 2 * numpy.pi * NR_TEETH_BIG / (BOLT_THREAD * NR_TEETH_SMALL)
+    print("For {} sec, final angle is {} rad => step angle is {}".format(time_in_sec, final_angle, sangle))
+    verif_final = debug_from_step_angle(sangle)
+          
+get_step_angle_from_time(int(sys.argv[1]))