Z8E001 Datasheet, PDF (22/49 Pages) Zilog, Inc. – CMOS OTP Microcontroller

Z8E001
CMOS OTP Microcontroller
STOP MODE OPERATION
The STOP Mode provides the lowest possible device
standby current. This instruction turns off the on-chip oscil-
lator and internal system clock.
To enter the STOP Mode, the Z8E001 only needs to exe-
cute a STOP instruction. It is NOT necessary to execute a
NOP instruction immediately before the STOP instruction.,
6F STOP ;enter STOP Mode
The STOP Mode is exited by any one of the following re-
sets: /RESET pin or a STOP-Mode Recovery source.
Upon reset generation, the processor will always restart
the application program at address 0020H and the STOP
Mode Flag will be set. Reading this flag does not clear it,
the user must clear this flag with software. Failure to clear
this flag may result in undefined behavior.
Zilog
The Z8E001 provides a dedicated STOP-Mode Recov-
ery (SMR) circuit. In this case, a low level applied to input
pin PB0 will trigger a SMR. To use this mode, pin PB0 (I/O
Port B, bit 0) must be configured as an input before the
STOP Mode is entered. The low level on PB0 must be held
for a minimum pulse width T_WSM.
Note: Use of the PB0 input for the stop mode recovery
does not initialize the control registers.
Note: The STOP Mode current (I_CC2) will be minimized
when:
s V_CC is at the low end of the devices operating range.
s Output current sourcing is minimized.
s All inputs (digital and analog) are at the low or high rail
voltages.
CLOCK
The Z8E001 MCU derives its timing from on-board clock
circuitry connected to pins XTAL1 and XTAL2. The clock
circuitry consists of an oscillator, a glitch filter, a divide-by-
two shaping circuit, a divide-by-four shaping circuit, and a
divide-by-eight shaping circuit. Figure 12 illustrates the
clock circuitry. The oscillator’s input is XTAL1 and its out-
put is XTAL2. The clock can be driven by a crystal, a ce-
ramic resonator, LC clock, or an external clock source.
XTAL1
XTAL2
Glitch
Filter
Machine
Clock
÷2
(5 cycles
per in-
struction)
÷4
Timer
Clock
÷8
WDT
Clock
Figure 14. Z8E001 Clock Circuit
22
PRELIMINARY
DS97Z8X1300