M16C62N Datasheet, PDF (25/213 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Software Wait
Mitsubishi microcomputers
M16C / 62N Group (80-pin)
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Software wait
A software wait can be inserted by setting the wait bit (bit 7) of the processor mode register 1 (address
000516) (Note).
A software wait is inserted in the internal ROM/RAM area by setting the wait bit of the processor mode
register 1. When set to “0”, each bus cycle is executed in one BCLK cycle. When set to “1”, each bus cycle
is executed in two BCLK cycles. After the microcomputer has been reset, this bit defaults to “0”. Set this bit
after referring to the recommended operating conditions (main clock input oscillation frequency) of the
electric characteristics.
The SFR area is always accessed in two BCLK cycles regardless of the setting of this control bit.
Table 1.8.1 shows the software wait and bus cycles. Figure 1.8.3 shows example bus timing when using
software waits.
Note: Before attempting to change the contents of the processor mode register 1, set bit 1 of the protect
register (address 000A16) to “1”.
Table 1.8.1. Software waits and bus cycles
Area
Wait bit
Bus cycle
SFR
Internal
ROM/RAM
Invalid
0
1
2 BCLK cycles
1 BCLK cycle
2 BCLK cycles
24