Figure 14.4C Write Timing Chart; Figure 14.4D Prl Write Operation Block Diagram - Fujitsu F2MC-16LX MB90580 Series Hardware Manual

14.4 Operations
(8) Reload register write timing
In a mode other than 16-bit PPG mode, it is recommended to use a word transfer instruction to write data
in reload registers PRLL and PRLH. If two byte transfer instructions are used to write a data item to these
registers, a pulse of unexpected width may be output depending on the timing.
PPG0
B B C B C C
A A D D

Figure 14.4c Write timing chart

Assume that PRLL is updated from A to C before point in the time chart above, and PRLH is updated
from B to D after point . Since the PRL values at point are PRLL=C and PRLH=B, a pulse of L side
count value C and H side count value B is output only once.
Similarly, to write data in PRL of ch0 and ch1 in 16-bit PPG mode, use a long word transfer instruction, or
use word transfer instructions in the order of ch0 and then ch1. In this mode, the data is only temporarily
written to ch0 PRL. Then, the data is actually written into ch0 PRL when the ch1 PRL is written to.
In a mode other than 16-bit PPG mode, ch0 and ch1 PRL are written independently.
ch0 PRL write data
ch1 PRL write data
Transferred in synchronization
with ch1 write in 16-bit
Temporary latch
PPG mode
ch0 write in a mode other
than 16-bit PPG mode
ch1 write
ch0 PRL ch1 PRL

Figure 14.4d PRL write operation block diagram

MB90580 Series Chapter 14: 8/16-Bit PPG 205