wrap notes

log/cl-step-control-log.md

@@ -1367,4 +1367,35 @@ Competing approaches would be
 
 I think the second manner is actually best, so I'm giving that a shot. First step I take is to translate from rotary measurements -> linear / unrolled-rotary position, wrapping around & incrementing a 'revolutions' count, then I calculate 'real position' with revs * angular_pos. 
 
-Just taking a minute to figure out the particulars on this one... `a r i t h m e t i c` 
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+Just taking a minute to figure out the particulars on this one... `a r i t h m e t i c` 
+
+OK, here's my counting-the-revs code
+
+```cpp
+    // stash this,
+    enc_reading = result;
+    // stash old measurement, pull new from LUT 
+    a_reading_last = a_reading;
+    a_reading = lut[result * 2]; 
+    // check for wraps around the circle,
+    // i.e. if we went from 359 -> 1 degs, we have gone around once, 
+    // if we went from 1 -> 359, we have decrimented one rev 
+    if(a_reading - a_reading_last > 180.0F){
+        revolutions --;
+    } else if (a_reading_last - a_reading > 180.0F){
+        revolutions ++;
+    }
+
+    // now we have a real position measurement:
+    p_est_last = p_est;
+    p_est = (float)revolutions * 360.0F + a_reading;
+```
+
+Now I can do the derivative, error, and integral all in terms of actual error on the long number line, no wrapping to worry about. Great: do it once, forget about it. 
+
+I think I'll get that back up and running... and target a wider range of positions, should be all tuned in already, and then I'm kind of finished with this step... next would be to bring it into a real machine context, benchtop test a new VM with an accel controller feeding it positions. 
+
+- re-integrate I and D terms
+- tune back in
+- set 'units per rev'
+- test, OK 
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