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Section 11 Multi-Function Timer Pulse Unit 2
R01UH0134EJ0400 Rev. 4.00 Page 551 of 2108
Sep 24, 2014
SH7262 Group, SH7264 Group
(h) Register Data Updating
In complementary PWM mode, the buffer register is used to update the data in a compare register.
The update data can be written to the buffer register at any time. There are five PWM duty and
carrier cycle registers that have buffer registers and can be updated during operation.
There is a temporary register between each of these registers and its buffer register. When
subcounter TCNTS is not counting, if buffer register data is updated, the temporary register value
is also rewritten. Transfer is not performed from buffer registers to temporary registers when
TCNTS is counting; in this case, the value written to a buffer register is transferred after TCNTS
halts.
The temporary register value is transferred to the compare register at the data update timing set
with bits MD3 to MD0 in the timer mode register (TMDR). Figure 11.43 shows an example of
data updating in complementary PWM mode. This example shows the mode in which data
updating is performed at both the counter crest and trough.
When rewriting buffer register data, a write to TGRD_4 must be performed at the end of the
update. Data transfer from the buffer registers to the temporary registers is performed
simultaneously for all five registers after the write to TGRD_4.
A write to TGRD_4 must be performed after writing data to the registers to be updated, even when
not updating all five registers, or when updating the TGRD_4 data. In this case, the data written to
TGRD_4 should be the same as the data prior to the write operation.