Z8F1680SH020SG Datasheet, PDF (45/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
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need to use this on-chip Program RAM to shadow Interrupt Service Routines (ISR). For
details, see the PRAM_M section on page 278.
3.2.
Program Memory
The eZ8 CPU supports 64 KB of Program Memory address space. The F1680 Series MCU
contains 8 KB to 24 KB of on-chip Flash memory in the Program Memory address space,
depending on the device.
In addition, the F1680 Series MCU contains up to 1 KB of on-chip Program RAM. The
Program RAM is mapped in the Program Memory address space beyond the on-chip Flash
memory. The Program RAM is entirely under user control and is meant to store interrupt
service routines of high-frequency interrupts. Since interrupts bring the CPU out of low-
power mode, it is important to ensure that interrupts that occur very often use as low a
current as possible. For battery operated systems, Program RAM based handling of high-
frequency interrupts provides power savings by keeping the Flash block disabled.
Program RAM (PRAM) is optimized for low-current operation and can be easily boot-
strapped with interrupt code at power up.
Reading from Program Memory addresses present outside the available Flash memory and
PRAM addresses returns FFH. Writing to these unimplemented Program Memory
addresses produces no effect. Table 6 describes the Program Memory maps for the F1680
Series MCU.
Table 6. F1680 Series MCU Program Memory Maps
Program Memory
Address (Hex)
Function
Z8F2480 Device
0000–0001
Flash option bits
0002–0003
Reset vector
0004–0005
WDT interrupt vector
0006–0007
Illegal instruction trap
0008–0037
Interrupt vectors*
0038–003D
Oscillator fail traps*
003E–5FFF
Program Flash
E000–E3FF
1 KB PRAM
Note: *See Table 36 on page 69 for a list of inter-
rupt vectors and traps.
PS025015-1212
PRELIMINARY
Address Space