The servos moved, and the arm wouldn't

I pushed the phone panel's stick and the servos in Bench didn't respond. They did move. The pod's firmware was working exactly as designed, for a board I don't have on the bench.

Two reasons it looked dead

The first is simple: the pod starts asleep. It sends no servo pulses until you wake it, because a servo's first pulse makes it jump. The LCD says PARK TO WAKE, and I'd missed it.

The second is the one worth writing down. Once awake, I pushed the boom stick forward and the boom went from 195 to 146 degrees, then stopped. The LCD said STOP boom hopper. The firmware has a collision guard that models Game Board 1: the hopper, the neighbouring pods, the pit's rim. It knows nothing about my desk, so it stopped the boom against a hopper that isn't there. With the boom stuck near 146, the swing stick refused to move too, so the whole arm looked dead.

Typing guard off in the Preview console fixed it. The boom ran down to 82 degrees, the stepper started stepping, and the stick and bucket followed. I'd tried the same command with an @ in front through the phone app's route and it did nothing, which cost a few minutes.

Making the 3D view move too

The bring-up board's 3D view was frozen. The model had no joints, so the dials were just printed parts. I added four joint sliders (swing, boom, stick, bucket) and each pointer now turns about its servo's shaft. They follow the firmware's @arm lines while Preview runs, so they move with the circuit.

The pointers show the servo's own angle, not the joint's. The boom's reads its joint angle minus 40, the offset in the firmware, so the dial can be compared with what a servo is really doing before the arm is built. All four turn anticlockwise from above in the model. I haven't checked that against the real servos, and if one runs backwards it's a one-character fix.

"It's working great," I told Claude, and the next question was limiters: the soft limits, each servo's real pulse range and direction. The bring-up board is where those get measured, so I'll put the numbers in the next entry.