M37221M6_03 Datasheet, PDF (47/62 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER with ON-SCREEN DISPLAY CONTROLLER

MITSUBISHI MICROCOMPUTERS
M37221M6-XXXSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER
with ON-SCREEN DISPLAY CONTROLLER
RESET CIRCUIT
The M37221M6-XXXSP is reset according to the sequence shown
in Figure 49. It starts the program from the address formed by using
the content of address FFFF16 as the high-order address and the
content of the address FFFE16 as the low-order address, when the
RESET pin is held at “L” level for 2 ms or more while the power source
voltage is 5 V ± 10 % and the oscillation of a quartz-crystal oscillator
or a ceramic resonator is stable and then returned to “H” level. The
internal state of microcomputer at reset are shown in Figure 51.
An example of the reset circuit is shown in Figure 50.
The reset input voltage must be kept 0.6 V or less until the power
source voltage surpasses 4.5 V.
XIN
φ
RESET
Internal RESET
SYNC
Address
Data
?
?
01, S 01, S-1 01, S-2 FFFE FFFF
ADH,
ADL
?
?
?
?
? ADL ADH
Reset address from the vector table
32768 count of XIN
clock cycle (Note 3)
Notes 1 : f(XIN) and f(φ) are in the relation : f(XIN) = 2·f (φ).
2 : A question mark (?) indicates an undefined state that
depends on the previous state.
3 : Immediately after a reset, timer 3 and timer 4 are
connected in hardware. At this time, “FF 16” is set
in timer 3 and “0716” is set to timer 4. Timer 3 counts down
with f(XIN)/16, and reset state is released by the timer 4
overflow signal.
Fig. 49. Reset sequence
Poweron
Power source voltage 0 V
4.5 V
Reset input voltage 0 V
0.6 V
1
5
M51953AL
4
3
0.1 µF
Fig. 50. Example of reset circuit
22
Vcc
25 _RESET
21 _Vss
M37221M6-XXXSP
46