retrofit.md

+# Retrofit
+
+* A sewing machine only turns one way, turn wheel toward operator / anti-clock
+  Forward/Backward sewing is done mechanically (hook movement reversed)
+
+## Add a rotary position sensor on the wheel
+
+* To detect needle position : up, down
+  can be two cams with a slotted optical sensor
+* To get a tachometer signal for speed control
+  can be a holed wheel with a slotted optical sensor
+
+* AMS AS5132 Rotary Sensor
+  8.5-bit rotary position sensor with digital angle (interface), ABI, UVW (up to 6 pole pairs) and PWM output
+  https://ams.com/as5132
+
+  360 positions per revolution
+  Serial interface
+  PWM output
+  Incremental output with adjustable number of pulses
+  Max RPM 72_900
+
+* AMS AS5134
+  https://ams.com/as5134
+  https://ams.com/as5134#tab/shop-now
+  https://www.mouser.fr/Search/Refine?Keyword=ams+AS5134
+  ZSST / ZSSM ??? tape/reel ???
+  8$/unit
+
+## Motor Driver