Telemetry#

Every frame the motor replies to carries telemetry, including drive frames — so a 50 Hz loop can read while it commands. transact is the method for that: send a frame, get the parsed reply back in one exchange.

use m0601::protocol::frame_velocity;

let frame = frame_velocity(motor.id(), 100, 1);
if let Some(fb) = motor.transact(&frame, std::time::Duration::from_millis(6))? {
    // A drive reply: fine 16-bit angle, but NO temperature.
    assert!(fb.temp_c.is_none());
    println!("{:+} RPM at {:.2}°", fb.speed_rpm, fb.position_deg);
}

The two layouts#

The catch is that the motor answers in two different frame layouts, and which one you get depends on the command that asked:

So the query reply is where temperature lives, and the drive reply is where the precise angle lives — about 128× finer. Neither carries both. The driver decodes each reply according to the command that elicited it, so Feedback always means the right thing; you never have to guess which layout you’re holding.

The Telemetry accumulator#

Now put those together in a real loop: you transact a drive frame every cycle for control, and slip in a query() every tenth cycle to refresh temperature. If you render straight off Feedback, temperature flickers — present on the tenth-cycle query reply, None on the nine drive replies in between. The angle flickers too, between coarse and fine.

Telemetry fixes this. It’s a small accumulator you feed each reply with absorb, and it retains the temperature and the hi-res angle across layouts:

use m0601::Telemetry;

let mut tel = Telemetry::default();
// in the loop:
if let Some(fb) = motor.transact(&frame, wait)? {
    tel.absorb(fb);
}
// tel.temp_c holds the last real temperature even on cycles whose reply had none;
// tel.position_deg keeps the fine angle rather than downgrading to the 8-bit one.

This is exactly what the CLI’s control and m0601-quad do to keep their dashboards from strobing — both hold a Telemetry in their shared state. (drive predates the type and hand-rolls a thinner version of the same idea: a local last_temp and a Feedback it only ever refreshes from drive replies. That works, but it is precisely the reconciliation Telemetry exists to save you.) If you’re building any loop that mixes drive frames and periodic queries, reach for Telemetry rather than doing it by hand.

Faults#

Feedback::faults is a Faults newtype over the fault byte, with named bits and a Display that spells them out (SensorErr | Overcurrent). Any bit outside the documented set is shown as hex rather than dropped, so the motor can never report a fault you don’t see. The trip and release thresholds are in the protocol reference; the short version is that the four electrical and mechanical protections auto-reset about five seconds after the trip — not after the condition clears, so a fault that persists simply re-trips — while overheat (0x10) has no timer at all and releases only when the winding cools from its 80 °C trip back to 75 °C.