Datasheet
NHET_LOOP_SYNC EXT_LOOP_SYNC
EXT_LOOP_SYNC
NHET_LOOP_SYNC
N2HET1
N2HET2
N2HETx
3
4
2
1
TMS570LS1224
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SPNS190B –OCTOBER 2012–REVISED FEBRUARY 2015
7.6.3 Input Timing Specifications
All of the N2HET channels have an enhanced pulse capture circuit. The N2HET instructions PCNT and
WCAP use this circuit to achieve the input timing requirements shown in Figure 7-10 and Table 7-23
below.
Figure 7-10. N2HET Input Capture Timings
Table 7-23. Input Timing Requirements for N2HET Channels with Enhanced Pulse Capture
PARAMETER MIN MAX UNIT
1, 2 Input signal period, PCNT or WCAP (HRP) (LRP) tc
(VCLK2)
+ 2 2
25
(HRP) (LRP) tc
(VCLK2)
- 2 ns
3 Input signal high phase, PCNT or WCAP 2 (HRP) tc
(VCLK2)
+ 2 2
25
(HRP) (LRP) tc
(VCLK2)
- 2 ns
4 Input signal low phase, PCNT or WCAP 2 (HRP) tc
(VCLK2)
+ 2 2
25
(HRP) (LRP) tc
(VCLK2)
- 2 ns
7.6.4 N2HET1-N2HET2 Synchronization
In some applications the N2HET resolutions must be synchronized. Some other applications require a
single time base to be used for all PWM outputs and input timing captures.
The N2HET provides such a synchronization mechanism. The Clk_master/slave (HETGCR.16) configures
the N2HET in master or slave mode (default is slave mode). A N2HET in master mode provides a signal
to synchronize the prescalers of the slave N2HET. The slave N2HET synchronizes its loop resolution to
the loop resolution signal sent by the master. The slave does not require this signal after it receives the
first synchronization signal. However, anytime the slave receives the re-synchronization signal from the
master, the slave must synchronize itself again..
Figure 7-11. N2HET1 – N2HET2 Synchronization Hookup
7.6.5 N2HET Checking
7.6.5.1 Internal Monitoring
To assure correctness of the high-end timer operation and output signals, the two N2HET modules can be
used to monitor each other’s signals as shown in Figure 7-12. The direction of the monitoring is controlled
by the I/O multiplexing control module.
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