diff --git a/ps4_lego_onebrain/ps4_lego_onebrain.ino b/ps4_lego_onebrain/ps4_lego_onebrain.ino
index fe78fff..112d9c2 100644
--- a/ps4_lego_onebrain/ps4_lego_onebrain.ino
+++ b/ps4_lego_onebrain/ps4_lego_onebrain.ino
@@ -7,6 +7,9 @@
  *
  * Model: Johnny 5 (Short Circuit) MOC, 7 motors across 2 hubs.
  *
+ * CONTROL SCHEME: tank drive. Every input drives exactly one motor - no
+ * mixing. See docs/CONTROLS.md.
+ *
  * Board package: esp32-bluepad32 4.1.0  (NOT the plain esp32 package)
  * Libraries:     none. No Legoino, no NimBLE - they would be a second host
  *                stack and that is exactly what we are avoiding.
@@ -76,11 +79,11 @@ static const int DEADZONE  = 40;    // raw stick counts, Bluepad32 range is +/-5
 // stop, and there is no position feedback here - holding a direction at a stop
 // stalls the motor. Keep these conservative; lower them if an axis feels forceful.
 static const int TRACK_MAX = 100;   // LWP3 power range is -100..100
-static const int HEAD_MAX  = 50;
+static const int HEAD_MAX  = 45;    // digital now, so this is the only speed
 static const int LIFT_MAX  = 60;
 static const int ARM_MAX   = 45;
 
-// Drive scaling: normal, L1 held (precision), R1 held (full).
+// Track scaling: normal, L1 held (precision), R1 held (full).
 static const int SCALE_NORMAL    = 75;
 static const int SCALE_PRECISION = 40;
 static const int SCALE_FULL      = 100;
@@ -522,6 +525,11 @@ void setup() {
     BP32.setup(&onConnectedController, &onDisconnectedController);
     BP32.enableVirtualDevice(false);
 
+    // Uncomment, flash once, re-pair, then comment out again if you ever end
+    // up with stale pairings. Bluepad32 keeps these in NVS and reflashing the
+    // sketch does not clear them.
+    // BP32.forgetBluetoothKeys();
+
     // Hubs first. Gamepad discovery gets switched on once they are up.
     BP32.enableNewBluetoothConnections(false);
 
@@ -556,7 +564,7 @@ void loop() {
 
     if (gp == nullptr) {
         clearDesired();
-    } else if (gp->b()) {                  // Circle - all stop
+    } else if (gp->l1() && gp->r1()) {     // both shoulders together - all stop
         clearDesired();
     } else {
 #if DEBUG_BUTTONS
@@ -570,31 +578,30 @@ void loop() {
         }
 #endif
 
-        // Arcade drive on the left stick. One stick for driving frees the
-        // right one entirely for the head, which is what Johnny emotes with.
-        int fwd  = stickToPower(-gp->axisY(), TRACK_MAX);
-        int turn = stickToPower(gp->axisX(), TRACK_MAX);
-
+        // Tank drive. One stick per track, vertical axis only. Nothing is
+        // mixed, so a stick can never command two motors.
         int scale = SCALE_NORMAL;
         if (gp->l1()) scale = SCALE_PRECISION;
         if (gp->r1()) scale = SCALE_FULL;
-        fwd = fwd * scale / 100;
-        turn = turn * scale / 100;
 
-        gDesired.leftTrack  = constrain(fwd + turn, -TRACK_MAX, TRACK_MAX);
-        gDesired.rightTrack = constrain(fwd - turn, -TRACK_MAX, TRACK_MAX);
+        gDesired.leftTrack  = stickToPower(-gp->axisY(),  TRACK_MAX) * scale / 100;
+        gDesired.rightTrack = stickToPower(-gp->axisRY(), TRACK_MAX) * scale / 100;
 
-        gDesired.headTurn = stickToPower(gp->axisRX(), HEAD_MAX);
-        gDesired.headTilt = stickToPower(-gp->axisRY(), HEAD_MAX);
+        // Head on the d-pad. Up/down tilts, left/right turns. Pressing a
+        // diagonal will move both, but only because you asked it to.
+        uint8_t d = gp->dpad();
+        gDesired.headTilt = (d & DPAD_UP)    ? HEAD_MAX
+                          : (d & DPAD_DOWN)  ? -HEAD_MAX : 0;
+        gDesired.headTurn = (d & DPAD_RIGHT) ? HEAD_MAX
+                          : (d & DPAD_LEFT)  ? -HEAD_MAX : 0;
 
-        // R2 raises, L2 lowers. Both are analog, 0..1023. Proportional control
-        // suits the heavy slow axis better than the sticks would.
+        // R2 raises, L2 lowers. Both are analog, 0..1023, so the lift keeps
+        // proportional control - it is the heavy axis that benefits most.
         gDesired.bodyLift = constrain(
             (gp->throttle() - gp->brake()) * LIFT_MAX / 1023, -LIFT_MAX, LIFT_MAX);
 
-        // Arms are pose-and-hold rather than modulate, so digital is fine.
-        uint8_t d = gp->dpad();
-        gDesired.leftArm  = (d & DPAD_UP) ? ARM_MAX : (d & DPAD_DOWN) ? -ARM_MAX : 0;
+        // Arms on the face buttons. Square/Circle left, Triangle/Cross right.
+        gDesired.leftArm  = gp->x() ? ARM_MAX : gp->b() ? -ARM_MAX : 0;
         gDesired.rightArm = gp->y() ? ARM_MAX : gp->a() ? -ARM_MAX : 0;
     }