Gregory's Server@developing_agent yes it pulses a GPIO pin and that clears the divider flip flop.
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6 comments
 @developing_agent the 2F region is once per revolution, so i think it doesn't matter as long as it is consistent. my guess is the edge between the 2F and 1.75MHz regions.  @tubetime If there's only one 2F region, what do you get multiple pulses of per revolution? (and need a divider chain for?) @developing_agent you get multiple pulses per revolution off the spindle motor's hall effect sensor. you need a way to divide this down (usually with a chain of T flip flops) to get a pulse that occurs once per revolution. the disk controller uses this to place the sectors in their correct locations. it needs to be in the same spot every time otherwise the controller will get confused. @tubetime Ah, so the divider chain is driven from the spindle hall effect sensor, and the single 2F region sets which hall pulse is the zero index. |
@tubetime I mean more like knowing when to do that (which 2F region should be the index pulse), or is that arbitrary and doesn't matter?