M16C/62P Group (M16C/62P, M16C/62PT)
8. Bus
Rev.2.41
Jan 10, 2006
Page 69 of 390
REJ09B0185-0241
NOTES:
1. To use the RDY signal, set this bit to “0”.
2. To access in multiplexed bus mode, set the corresponding bit of CS0W to CS3W to “0” (with wait
state).
3. When the selected CPU clock source is the PLL clock, the number of wait cycles can be altered by
the PM20 bit in the PM2 register. When using a 16 MHz or higher PLL clock, be sure to set the
PM20 bit to “0” (2 wait cycles).
4. After reset, the PM17 bit is set to “0” (without wait state), all of the CS0W to CS3W bits are set to “0”
(with wait state), and the CSE register is set to “00h” (one wait state for CS0 to CS3). Therefore, the
internal RAM and internal ROM are accessed with no wait states, and all external areas are
accessed with one wait state.
5. When PM17 bit is set to “1” and accesses an external area, set the CSiW (i=0 to 3) bits to “0” (with
wait state).
Table 8.8
Bit and Bus Cycle Related to Software Wait
Area
Bus Mode
PM2
Register
PM20 Bit
PM1
Register
PM17 Bit
(5)
CSR Register
CS3W Bit
(1)
CS2W Bit
(1)
CS1W Bit
(1)
CS0W Bit
(1)
CSE Register
CSE31W to CSE30W Bit
CSE21W to CSE20W Bit
CSE11W to CSE10W Bit
CSE01W to CSE00W Bit
Software
Wait
Bus Cycle
SFR
−
1
−
−
−
−
2 BCLK cycles
(3)
−
0
−
−
−
−
3 BCLK cycles
(3)
Internal
RAM,
ROM
−
−
0
−
−
No wait
1 BCLK cycle
(4)
−
−
1
−
−
1 wait
2 BCLK cycles
External
Area
Separate
Bus
−
0
1
00b
No wait
1 BCLK cycle
(read)
2 BCLK cycles
(write)
−
−
0
00b
1 wait
2 BCLK cycle
(4)
−
−
0
01b
2 waits
3 BCLK cycles
−
−
0
10b
3 waits
4 BCLK cycle
−
1
0
00b
1 wait
2 BCLK cycle
Multiplexed
Bus
(2)
−
−
0
00b
1 wait
3 BCLK cycles
−
−
0
01b
2 waits
3 BCLK cycles
−
−
0
10b
3 waits
4 BCLK cycles
−
1
0
00b
1 wait
3 BCLK cycles
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