

-----------------------------------

nobody

02 Sep 2018 14:07



-----------------------------------

Referitor la acel al optulea pas mai puternic, din documentatia driver-ului A4988, poate ajuta la ceva:

Mixed Decay Operation. For some applications where microstepping at very low speeds is necessary, the lack of back EMF in the winding causes the current to increase in the load quickly, resulting in missed steps. This is shown in Figure 2. By pulling the ROSC pin to ground, mixed decay is set to be active 100% of the time, for both rising and falling currents, and prevents missed steps as shown in Figure 3.

Low Current Microstepping. Intended for applications where the minimum on-time prevents the output current from regulating to the programmed current level at low current steps. To prevent this, the device can be set to operate in Mixed decay mode on both rising and falling portions of the current waveform. This feature is implemented by shorting the ROSC pin to ground.

La Big-Easy Driver, acel pin nu este legat direct la masa (ci cu un rezistor de 20k - adica foloseste modul ala cu salturi la turatii mici), dar se poate face relativ usor. Exemplul din documentatie este la 8 micropasi/s, deci cred ca putem considera viteza folosita ca fiind "very low speed".

P.S.
In loc de RTC puteti folosi GPS ... dar oare chiar este nevoie ?

