
CHAPTER 4 BUS CONTROL FUNCTION
User’s Manual U12688EJ4V0UM00
115
4.6.4 Bus cycles in which the wait function is valid
In the V850E/MS1, the number of waits can be specified according to the type of memory specified for each
memory block.
The registers which set the bus cycles and waits in which the wait function is valid are as shown below.
Table 4-1. Bus Cycles in Which the Wait Function Is Valid (1/2)
Programmable Wait Setting
Bus Cycle
Type of Wait
Higher Order: Register
Lower Order: Bit
Number
of Waits
Wait by
WAIT Pin
DWC1, DWC2
SRAM, external ROM, external I/O cycle
Data access wait
DWxx
0 to 7
{
DWC1, DWC2
Off-page
Data access wait
DWxx
0 to 7
{
PRC
Page ROM cycle
On-page
Data access wait
PRW0 to PRW2
0 to 7
{
DRCn
RAS pre-charge
RPC0n, RPC1n
0 to 3
×
DRCn
Row address hold
RHC0n, RHC1n
0 to 3
×
DRCn
Off-page
Data access wait
DAC0n, DAC1n
0 to 3
Note
DRCn
CAS pre-charge
CPC0n, CPC1n
0 to 3
×
DRCn
Read access
On-page
Data access wait
DAC0n, DAC1n
0 to 3
×
DRCn
RAS pre-charge
RPC0n, RPC1n
0 to 3
×
DRCn
Row address hold
RHC0n, RHC1n
0 to 3
Note
DRCn
Off-page
Data access wait
DAC0n, DAC1n
0 to 3
×
DRCn
CAS pre-charge
CPC0n, CPC1n
0 to 3
×
DRCn
EDO DRAM, high-
speed page DRAM
cycle
Write access
On-page
Data access wait
DAC0n, DAC1n
0 to 3
×
RWC
RAS pre-charge
RRW0, RRW1
0 to 3
×
RWC
CBR refresh cycle
RAS active width
RCW0 to RCW2
0 to 7
×
Note EDO DRAM cycle:
×
High-speed page DRAM cycle:
{
Remarks 1.
{
: Valid
×
: Invalid
2. n = 0 to 3
xx = 00 to 02, 10 to 12, 20 to 22, 30 to 32, 40 to 42, 50 to 52, 60 to 62, 70 to 72
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