Write Data Buffer Function; Write Data Buffer Function For Peripheral Module; Figure 6.3 Example Of Timing When Write Data Buffer Function Is Used - Renesas H8SX/1520 Series Hardware Manual

Section 6 Bus Controller (BSC)
6.6

Write Data Buffer Function

6.6.1

Write Data Buffer Function for Peripheral Module

This LSI has a write data buffer function for the peripheral module. Using the write data buffer
function enables external writes and on-chip memory accesses in parallel. The write data buffer
function is made available by setting the PWDBE bit in BCR2 to 1.
Figure 6.3 shows an example of the timing when the write data buffer function is used. When this
function is used, if a peripheral module write continues for two cycles or longer, and there is an
internal access next, only the peripheral module write is executed in the first two cycles. However,
from the next cycle onward, on-chip memory accesses and the external address space write rather
than waiting until it ends are executed in parallel.

Figure 6.3 Example of Timing when Write Data Buffer Function is Used

Rev. 3.00 Mar. 14, 2006 Page 130 of 804
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Iφ
Internal address bus
Pφ
Internal peripheral
address bus
Internal peripheral
data bus
On-chip
memory
read
Peripheral module write
Peripheral module address