I measured some numbers.
Homing dot X coordinate while moving the carriage by 0.035 mm (which is about 1 microstep):
36, 54, 79, 115, 145, 163, 224, 242, 278, 315, 351, 387, 424
36, 61, 85, 115, 151, 169, 230, 242, 284, 315, 351, 387, 430, 448, 448, 514, 526
696, 666, 629, 599, 569, 545, 496, 490, 460, 424, 387, 351, 321, 284, 266, 218, 194, 157, 121, 85, 48, 12
- figure_4.png (90.33 KiB) Viewed 11121 times
(Maybe the plateau at 13 - 14 steps is due to 0.035 mm is slightly less than the microstep , and no actual step was performed at this moment)
Winding voltages vs steps:
-1262, -1615, -1911, -2160, -2302, -2358, -2188, -2051, -1815, -1516, -1159, -731, -293, 0, 687, 868, 1284, 1645, 1947, 2195, 2348, 2405, 2227, 2090, 1847, 1544, 1181, 745, 299, 0, -676, -878, -1299, -1668, -1981
-1788, -1510, -1154, -730, -294, 0, 692, 866, 1274, 1632, 1930, 2169, 2359, 2380, 2188, 2052, 1813, 1521, 1165, 738, 303, 0, -688, -877, -1297, -1656, -1968, -2199, -2366, -2411, -2230, -2087, -1850, -1552, -1190
- figure_5.png (48.65 KiB) Viewed 11120 times
- figure_8.png (47.49 KiB) Viewed 11121 times
- figure_10.png (55.54 KiB) Viewed 11121 times
So i think the drv8818 is not the best possible driver.