HET[2]
ext. ref.
signal
APCNT
period
counter
ACF
Accel.
flag
ACNT
angle
generator
Singularity
GPF
Gap flag
Gap End
Gap Start
Angle Functions
994
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
High-End Timer (N2HET) Module
Figure 23-34. N2HET Timings Associated with the Gap Flag (ACNT Acceleration)
23.3.1.2 APCNT Underflow
The fastest valid external signal APCNT can accept must satisfy the following condition:
Step Width K < Period Min. Resolution (LRP)
This condition fixes the maximum possible step width once the minimum period and the resolution of an
application are specified.
If a period value accidentally falls below the minimum allowed, APCNT stops the capture of these periods
and sets the APCNT underflow interrupt flag located in the exceptions interrupt control register. In such a
situation, SCNT and ACNT continue to be executed using the last valid period captured by APCNT.
23.3.1.3 APCNT Overflow
The slowest valid external signal APCNT can measure must satisfy the following condition:
Period Max Resolution < 33554431
When this limit is reached (APCNT Count equals all 1’s), APCNT stays at a maximum count (stops
counting). APCNT remains in this position until the next specified capture edge is detected on the selected
pin and sets the APCNT overflow interrupt flag located in the exceptions interrupt control register. In this
situation, SCNT and ACNT continue to be executed using the maximum APCNT period count.