@@ -143,7 +143,12 @@ enables the CAN bus, so the motion rule above applies to it too. `piper_sdk` and
 are installed in a user venv at `~/piper-venv` (Debian's system Python has no pip, so this
 is the only place they live). [`scripts/piper_up_down.py`](scripts/piper_up_down.py) is the
 first motion script. Copy it to the Pi and run it with `~/piper-venv/bin/python`. Without
-`--go` it only reads joint state.
+`--go` it only reads joint state. The arm's rest pose has the wrist off zero (about J5 22°,
+J6 61°), so the all-joint zero check refuses to start from rest. Use `--hold-wrist` there,
+which moves only J2/J3 and holds the other joints where they are. First motion: 2026-10-09,
+PR #16, `--go --hold-wrist`, 3 cycles of ±25° at 20% speed, each pose reached in 0.8 s.
+To record a run, use `rpicam-vid --codec mjpeg`. The Pi 5 has no H.264 encoder, this build
+has no libav, and the Pi has no ffmpeg, so the default and `--codec libav` both write nothing.
 
 **Using the Pi as a proxy.** Some vendor sites (and YouTube's player) block GitHub Actions IP
 ranges; the Pi's residential IP is not blocked. The Pi is on constrained Wi-Fi and may be
 
@@ -8,16 +8,19 @@
 
 "Up" is the shoulder (J2) lifting by --lift-deg while the elbow (J3) opens by the same
 amount, so the forearm keeps roughly its angle and the whole arm rises. Every other joint
-holds zero. can0 must already be up at 1 Mbit/s; this script never touches the interface.
+holds zero, or with --hold-wrist holds the angle it started at (the PiPER rests with its
+wrist off zero, so this raises the arm without swinging the wrist). can0 must already be up
+at 1 Mbit/s; this script never touches the interface.
 
 Safety:
 - Without --go nothing is sent to the arm.
 - Refuses to start unless joint feedback is live and every joint is within --zero-tol-deg
-  of zero.
+  of zero (only J2 and J3 with --hold-wrist).
 - Waits for each pose to be reached before the next; a pose that is not reached in
   --timeout-s aborts the cycle.
-- Always commands zero before exiting, and disables the motors only once the arm is back
-  at zero. Disabling elsewhere would drop the arm, so then it is left enabled and holding.
+- Always commands the start pose before exiting, and disables the motors only once the arm
+  is back there. Disabling elsewhere would drop the arm, so then it is left enabled and
+  holding.
 """
 import argparse
 import os
@@ -74,6 +77,8 @@ def main():
     ap.add_argument("--tol-deg", type=float, default=1.5, help="pose reached tolerance")
     ap.add_argument("--zero-tol-deg", type=float, default=5.0, help="start/end zero tolerance")
     ap.add_argument("--timeout-s", type=float, default=15.0, help="per-pose timeout")
+    ap.add_argument("--hold-wrist", action="store_true",
+                    help="hold J1 and J4-J6 at their starting angles instead of zero")
     args = ap.parse_args()
 
     if not 0 < args.lift_deg <= 45:
@@ -97,15 +102,18 @@ def main():
     print("joints (deg):", fmt(q0))
     print("enabled:", piper.GetArmEnableStatus())
     print(piper.GetArmStatus())
-    if any(abs(v) > args.zero_tol_deg for v in q0):
+    checked = q0[1:3] if args.hold_wrist else q0
+    if any(abs(v) > args.zero_tol_deg for v in checked):
         sys.exit(f"arm is not within {args.zero_tol_deg} deg of zero; not moving")
+
+    home = [q0[0], 0.0, 0.0, *q0[3:]] if args.hold_wrist else [0.0] * 6
+    up = [home[0], args.lift_deg, -args.lift_deg, *home[3:]]
+    print("home (deg):", fmt(home))
+    print("up   (deg):", fmt(up))
     if not args.go:
         print("read-only run (no --go): nothing sent to the arm")
         return
 
-    zero = [0.0] * 6
-    up = [0.0, args.lift_deg, -args.lift_deg, 0.0, 0.0, 0.0]
-
     t0 = time.time()
     while not piper.EnablePiper():
         if time.time() - t0 > 5:
@@ -121,21 +129,21 @@ def main():
                 break
             time.sleep(args.pause_s)
             print(f"cycle {i}/{args.cycles}: down", flush=True)
-            if not move_to(piper, zero, args.speed, args.tol_deg, args.timeout_s):
+            if not move_to(piper, home, args.speed, args.tol_deg, args.timeout_s):
                 break
             time.sleep(args.pause_s)
             completed += 1
     finally:
-        print("returning to zero", flush=True)
-        move_to(piper, zero, args.speed, args.tol_deg, args.timeout_s)
+        print("returning home", flush=True)
+        move_to(piper, home, args.speed, args.tol_deg, args.timeout_s)
         q = joints_deg(piper)
-        if all(abs(v) <= args.zero_tol_deg for v in q):
+        if all(abs(a - b) <= args.zero_tol_deg for a, b in zip(q, home)):
             t0 = time.time()
             while piper.DisablePiper() and time.time() - t0 < 5:
                 time.sleep(0.01)
-            print("disabled at zero:", fmt(q), flush=True)
+            print("disabled at home:", fmt(q), flush=True)
         else:
-            print("WARNING: not back at zero, leaving motors enabled so the arm does not drop:",
+            print("WARNING: not back home, leaving motors enabled so the arm does not drop:",
                   fmt(q), flush=True)
         print(f"completed {completed}/{args.cycles} cycles", flush=True)