CHAPTER 29 CAUTIONS FOR WAIT
Preliminary User’s Manual U16315EJ1V0UD
428
29.2 Peripheral Hardware That Generates Wait
Table 29-1 lists the registers that issue a wait request when accessed by the CPU, and the number of CPU wait
clocks.
Table 29-1. Registers That Generate Wait and Number of CPU Wait Clocks
Peripheral Hardware
Register
Access
Number of Wait Clocks
Watchdog timer
WDTM
Write
3 clocks (fixed)
Serial interface UART0
ASIS0
Read
1 clock (fixed)
Serial interface UART6
ASIS6
Read
1 clock (fixed)
ADM
Write
ADS
Write
PFM
Write
PFT
Write
2 to 5 clocks
Note
(when ADM.5 flag = “1”)
2 to 9 clocks
Note
(when ADM.5 flag = “0”)
ADCR
Read
1 to 5 clocks
(when ADM.5 flag = “1”)
1 to 9 clocks
(when ADM.5 flag = “0”)
A/D converter
<Calculating maximum number of wait clocks>
{(1/f
MACRO
)
×
2/(1/f
CPU
)} + 1
*The result after the decimal point is truncated if it is less than t
CPUL
after it has been multiplied by
(1/f
CPU
), and is rounded up if it exceeds t
CPUL
.
f
MACRO
:
Macro operating frequency
(When bit 5 (FR2) of ADM = “1”: f
X
/2, when bit 5 (FR2) of ADM = “0”: f
X
/2
2
)
f
CPU
:
CPU clock frequency
t
CPUL
:
Low-level width of CPU clock
Note
No wait cycle is generated for the CPU if the number of wait clocks calculated by the above expression is 1.
Remarks 1.
The clock is the CPU clock (f
CPU
).
2.
When the CPU is operating on the subsystem clock and the X1 input clock is stopped, do not access the
registers listed above using an access method in which a wait request is issued.
Содержание 78K0/KD1 Series
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