HD6437020 Datasheet, PDF (285/507 Pages) Hitachi Semiconductor – SuperH™ RISC engine

Buffer Transfers when Changing from Increment to Decrement: When the contents of the GR
are within GRA3 – T + 1 and GRA3, do not transfer a value outside this range. When the contents
of GR are outside this range, do not a transfer a value within it. Figure 10.39 illustrates a point of
caution regarding changing of GR settings with a buffer operation.
GRA3 + 1
GRA3
GRA3 – T + 1
GRA3 – T
Changes inhibited
TCNT3
TCNT4
Figure 10.39 Caution for Changing GR Settings with Buffer Operation (1)
Buffer Transfers when Changing from Decrement to Increment: When the contents of the GR
are within H'0000 to T–1, do not transfer a value outside this range. When the contents of GR are
outside this range, do not transfer a value within it. Figure 10.40 illustrates this point of caution
regarding changing of GR settings with a buffer operation
TCNT4
T
T–1
H' 0000
H' FFFF
TCNT3
Changes inhibited
Figure 10.40 Caution for Changing GR Settings with Buffer Operation (2)
When GR Settings are Outside the Count Range (H'0000–GRA3): Waveforms of duty cycle
0% and 100% can be output by setting GR outside the count area. Be sure to make the direction of
the count (increment/decrement) when writing a setting from outside the count area into the buffer
register (BR) the same as the count direction when writing the setting that returns to within the
count area in the BR.
HITACHI 271