SH7052 Datasheet, PDF (366/919 Pages) Renesas Technology Corp – SuperHTM RISC engine

corresponding timer interrupt enable register (TIER) is set to 1 at this time, an interrupt request is
sent to the CPU. After overflowing, TCNT starts counting up again from H'00000000 or H'0000.
If the TSTR value is cleared to 0 during TCNT operation, the corresponding TCNT halts. In this
case, TCNT is not reset. If external output is being performed from the GR for the corresponding
TCNT, the output value does not change.
Channel 0 free-running counter operation is shown in figure 10.13.
Pø
TSTR
TST0
TCNT0
Clock
TCNT0
TSR0
OVF0
00000001
00000001 00000002 00000003 00000004 00000005 FFFFFFFD FFFFFFFE FFFFFFFF 00000000 00000001 00000002
Cleared by software
Figure 10.13 Free-Running Counter Operation and Overflow Timing
The free-running counters (TCNT) in ATU-II channels 6 and 7 perform cyclic count operations
unconditionally. With channel 3 to 5 free-running counters (TCNT), when the corresponding
T3PWM to T5PWM bit in the timer mode register (TMDR) is set to 1, or the corresponding CCI
bit in the timer I/O control register (TIOR) is set to 1 when bits T3PWM to T5PWM are 0, the
counter for the relevant channel performs a cyclic count. The relevant TCNT counter is cleared by
a compare-match of TCNT with GR3D, GR4D, or GR5D in channel 3 to 5, or CYLR in channels
6 and 7 (counter clear function). TCNT starts counting up as a cyclic counter when the
corresponding STR bit in TSTR is set to 1 after the TMDR setting is made. When the count value
matches the GR3D, GR4D, GR5D, or CYLR value, the corresponding IMF3D, IMF4D, or IMF5D
bit in the timer status register (TSR) (or the CMF bit in TSR6 or TSR7 for channels 6 and 7) is set
to 1, and TCNT is cleared to H'0000 (H'0001 in channels 6 and 7).
If the corresponding TIER bit is set to 1 at this time, an interrupt request is sent to the CPU. After
the compare-match, TCNT starts counting up again from H'0000 (H'0001 in channels 6 and 7).
Figure 10.14 shows the operation when channel 3 is used as a cyclic counter (with a cycle setting
of H'0008).
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